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In this article, let’s walk through how I created an extension in Visual Studio Code
My motto…when you have a problem, do something about. I hated stubbing out Python classes so I created an extension in Visual Studio Code to do it for me. In this article, let’s walk through how I created that extension. We will use several techniques to do so.
Create a new extension, prompt the user for input, convert the input to a string that represents the new class file, and write out tha
Check out the end result HERE.
To get started with developing Code extensions, you’ll need two different NPM packages installed, “yo” and “generator-code”. If you’re looking for a little more background on creating VS Code extensions, check out Creating Your First Visual Studio Code Extension!
To generate your project, run the following command.
yo code
This will follow up by asking you several questions about your project. Choose either JavaScript or TypeScript for your extension.
After answering all of the questions, open the newly created project in Code.
You’ll have a several different files created for you, the two most important are the package.json and extension.js files.
Start by opening the extension.js file. Then, rename the extension command name to “createPyClass”.
Then, in the package.json file, rename the activation event and command to match the name of the command.
Update the title as well, which is what the user will type to activate the command.
To run the extension, open the debug panel (looks like a bug) and press play. This will open up a new instance of VS Code. Open the command prompt (Command+Shift+P on Mac and Control+Shift+P on Windows) and type “Create Python Class”.
And you should see the “Hello World” message.
Here comes the tricky part. We need to prompt the user for input about the class (class name and properties) and convert that input into a string that we can write to the new class file.
Let’s start by ensuring the user has a folder currently open. If not, we don’t have a place to write the new class file to. If the user does not have a folder open, we show an error message and return.
if (!vscode.workspace.workspaceFolders) {
return vscode.window.showErrorMessage(
"Please open a directory before creating a class."
);
}
Now, we can ask the user for the name of the class he/she wants to create. If the user, for some reason, closes the input prompt (by hitting escape) we return.
const className = await vscode.window.showInputBox({
prompt: "Class Name?"
});
if (!className) return;
Now, a bit of a tricky part. We want to let the user input as many properties as he/she wants to. For this we prompt initially for a property, then run a while loop retrieving properties until the user enters ‘done’.
let count = 1;
let property = await vscode.window.showInputBox({
prompt: `Property #${count}? ('done' when finished)`
});
const properties = [];
while (property != "done") {
properties.push(property);
count++;
property = await vscode.window.showInputBox({
prompt: `Property #${count}? ('done' when finished)`
});
}
This might be a good point to rerun you extension, enter in valid inputs, and print the user’s info just to be sure it looks right.
Now, we start to take the users input to generate the content of the class. Let’s start by creating the class definition line as well as the constructor definition.
const classDefinition = `class ${className}:`;
const constructorDefinition = `def __init__(self, ${properties.join(", ")}):`;
Then, we can create the constructor assignments lines. This is where the user will initialize variables on itself, using the values of the constructor parameters. For this, we use map (as we will from now on) to convert each of the property inputs in some way.
const constructorAssignments = properties
.map(property => `self.${property} = ${property}\n\t\t`)
.join("");
Now, for each property, we create a getter function. Again, we use map to convert each property into a string that represents its getter.
const classGetters = properties
.map(
property => `\tdef get_${property}(self):\n\t\treturn self.${property}\n\n`
)
.join("");
And the last thing we want to create is the string function that will tell Python how to print this object. This one is pretty tricky. Again, we use the map function to convert each property by printing the name of the property and then it’s value.
Notice that in the map return value, we are adding a comma and a plus. This means for the last property, we would be adding unnecessary characters at the end. For this reason, we convert the resulting array to a string and chop of the last 11 characters by using splice.
const dunderStrString = `\tdef __str__():\n \t\treturn ${properties
.map(property => '"' + property + ': "' + " + " + property + ' + " , " + ')
.join("")
.slice(0, -11)}`;
Let’s take this individual pieces and put them all together!
const classString = `${classDefinition}
${constructorDefinition}
${constructorAssignments}
${classGetters}
${dunderStrString}`;
I would recommend creating a log statement and running this again to make sure your class string looks good!
Whew, that was a lot, but it gets easier from here. Now, we need to write that string to a new file. To work with files, we need to import the “fs” and “path” modules from Node at the top of the page.
const fs = require("fs");
const path = require("path");
Then, we need to get the path for the user’s currently open directory. This was a bit tricky for me. You can get a reference to open directories by vscode.workspace.workspaceFolders
. Then, we get the first one from the resulting array, grab it’s uri, and convert it to a string. The resulting path string included a prefix, so we strip that out by splitting by a colon and grabbing what comes after the colon.
const folderPath = vscode.workspace.workspaceFolders[0].uri
.toString()
.split(":")[1];
Now we can use the fs module, the folder path, and the name of the class file, to write the class string to our new file!
fs.writeFile(path.join(folderPath, `${className}.py`), classString, err => {});
We can take it one step further by providing the user some feedback based on whether or not the write file was successful.
fs.writeFile(path.join(folderPath, `${className}.py`), classString, err => {
if (err) {
vscode.window.showErrorMessage("Something went wrong");
return console.log(err);
}
vscode.window.showInformationMessage(`${className} Class created.`);
});
Either refresh your debugging instance or start again by following the steps above. With the debug instance of VS Code open, run your “Create Python Class” command again. Then, enter the name of the class your want to create. “Person” in this case.
Then enter your properties, “name” first.
Then “age”.
Then “done” to finish.
Hopefully, yours says that the file was successfully created.
Then, double check your file was actually created and it looks good!
Again, if you struggle with something in your development process, work to improve it. In this case I created an extension to solve a specific problem I had. It’s also something that others will benefit from as well. Not to mention, it was a great learning opportunity!
#python #visual-studio
1675304280
We are back with another exciting and much-talked-about Rails tutorial on how to use Hotwire with the Rails application. This Hotwire Rails tutorial is an alternate method for building modern web applications that consume a pinch of JavaScript.
Rails 7 Hotwire is the default front-end framework shipped with Rails 7 after it was launched. It is used to represent HTML over the wire in the Rails application. Previously, we used to add a hotwire-rails gem in our gem file and then run rails hotwire: install. However, with the introduction of Rails 7, the gem got deprecated. Now, we use turbo-rails and stimulus rails directly, which work as Hotwire’s SPA-like page accelerator and Hotwire’s modest JavaScript framework.
Hotwire is a package of different frameworks that help to build applications. It simplifies the developer’s work for writing web pages without the need to write JavaScript, and instead sending HTML code over the wire.
Introduction to The Hotwire Framework:
It uses simplified techniques to build web applications while decreasing the usage of JavaScript in the application. Turbo offers numerous handling methods for the HTML data sent over the wire and displaying the application’s data without actually loading the entire page. It helps to maintain the simplicity of web applications without destroying the single-page application experience by using the below techniques:
Turbo Frames: Turbo Frames help to load the different sections of our markup without any dependency as it divides the page into different contexts separately called frames and updates these frames individually.
Turbo Drive: Every link doesn’t have to make the entire page reload when clicked. Only the HTML contained within the tag will be displayed.
Turbo Streams: To add real-time features to the application, this technique is used. It helps to bring real-time data to the application using CRUD actions.
It represents the JavaScript framework, which is required when JS is a requirement in the application. The interaction with the HTML is possible with the help of a stimulus, as the controllers that help those interactions are written by a stimulus.
Not much information is available about Strada as it has not been officially released yet. However, it works with native applications, and by using HTML bridge attributes, interaction is made possible between web applications and native apps.
Simple diagrammatic representation of Hotwire Stack:
As we are implementing the Ruby on Rails Hotwire tutorial, make sure about the following installations before you can get started.
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Contact Bacancy today and hire Ruby developers to start building your dream project!
Find the following commands to create a rails application.
mkdir ~/projects/railshotwire
cd ~/projects/railshotwire
echo "source 'https://rubygems.org'" > Gemfile
echo "gem 'rails', '~> 7.0.0'" >> Gemfile
bundle install
bundle exec rails new . --force -d=postgresql
Now create some files for the project, up till now no usage of Rails Hotwire can be seen.
Fire the following command in your terminal.
echo "class HomeController < ApplicationController" > app/controllers/home_controller.rb
echo "end" >> app/controllers/home_controller.rb
echo "class OtherController < ApplicationController" > app/controllers/other_controller.rb
echo "end" >> app/controllers/home_controller.rb
echo "Rails.application.routes.draw do" > config/routes.rb
echo ' get "home/index"' >> config/routes.rb
echo ' get "other/index"' >> config/routes.rb
echo ' root to: "home#index"' >> config/routes.rb
echo 'end' >> config/routes.rb
mkdir app/views/home
echo '<h1>This is Rails Hotwire homepage</h1>' > app/views/home/index.html.erb
echo '<div><%= link_to "Enter to other page", other_index_path %></div>' >> app/views/home/index.html.erb
mkdir app/views/other
echo '<h1>This is Another page</h1>' > app/views/other/index.html.erb
echo '<div><%= link_to "Enter to home page", root_path %></div>' >> app/views/other/index.html.erb
bin/rails db:create
bin/rails db:migrate
Additionally, you can clone the code and browse through the project. Here’s the source code of the repository: Rails 7 Hotwire application
Now, let’s see how Hotwire Rails can work its magic with various Turbo techniques.
Go to your localhost:3000 on your web browser and right-click on the Inspect and open a Network tab of the DevTools of the browser.
Now click on go to another page link that appears on the home page to redirect from the home page to another page. In our Network tab, we can see that this action of navigation is achieved via XHR. It appears only the part inside HTML is reloaded, here neither the CSS is reloaded nor the JS is reloaded when the navigation action is performed.
By performing this action we can see that Turbo Drive helps to represent the HTML response without loading the full page and only follows redirect and reindeer HTML responses which helps to make the application faster to access.
This technique helps to divide the current page into different sections called frames that can be updated separately independently when new data is added from the server.
Below we discuss the different use cases of Turbo frame like inline edition, sorting, searching, and filtering of data.
Let’s perform some practical actions to see the example of these use cases.
Make changes in the app/controllers/home_controller.rb file
#CODE
class HomeController < ApplicationController
def turbo_frame_form
end
def turbo_frame submit
extracted_anynumber = params[:any][:anynumber]
render :turbo_frame_form, status: :ok, locals: {anynumber: extracted_anynumber, comment: 'turbo_frame_submit ok' }
end
end
Add app/views/home/turbo_frame_form.html.erb file to the application and add this content inside the file.
#CODE
<section>
<%= turbo_frame_tag 'anyframe' do %>
<div>
<h2>Frame view</h2>
<%= form_with scope: :any, url: turbo_frame_submit_path, local: true do |form| %>
<%= form.label :anynumber, 'Type an integer (odd or even)', 'class' => 'my-0 d-inline' %>
<%= form.text_field :anynumber, type: 'number', 'required' => 'true', 'value' => "#{local_assigns[:anynumber] || 0}", 'aria-describedby' => 'anynumber' %>
<%= form.submit 'Submit this number', 'id' => 'submit-number' %>
<% end %>
</div>
<div>
<h2>Data of the view</h2>
<pre style="font-size: .7rem;"><%= JSON.pretty_generate(local_assigns) %></pre>
</div>
<% end %>
</section>
Make some adjustments in routes.rb
#CODE
Rails.application.routes.draw do
get 'home/index'
get 'other/index'
get '/home/turbo_frame_form' => 'home#turbo_frame_form', as: 'turbo_frame_form'
post '/home/turbo_frame_submit' => 'home#turbo_frame_submit', as: 'turbo_frame_submit'
root to: "home#index"
end
#CODE
<h1>This is Rails Hotwire home page</h1>
<div><%= link_to "Enter to other page", other_index_path %></div>
<%= turbo_frame_tag 'anyframe' do %>
<div>
<h2>Home view</h2>
<%= form_with scope: :any, url: turbo_frame_submit_path, local: true do |form| %>
<%= form.label :anynumber, 'Type an integer (odd or even)', 'class' => 'my-0 d-inline' %>
<%= form.text_field :anynumber, type: 'number', 'required' => 'true', 'value' => "#{local_assigns[:anynumber] || 0}", 'aria-describedby' => 'anynumber' %>
<%= form.submit 'Submit this number', 'id' => 'submit-number' %>
<% end %>
<div>
<% end %>
After making all the changes, restart the rails server and refresh the browser, the default view will appear on the browser.
Now in the field enter any digit, after entering the digit click on submit button, and as the submit button is clicked we can see the Turbo Frame in action in the below screen, we can observe that the frame part changed, the first title and first link didn’t move.
Turbo Streams deliver page updates over WebSocket, SSE or in response to form submissions by only using HTML and a series of CRUD-like operations, you are free to say that either
This transmit can be represented by a simple example.
#CODE
class OtherController < ApplicationController
def post_something
respond_to do |format|
format.turbo_stream { }
end
end
end
Add the below line in routes.rb file of the application
#CODE
post '/other/post_something' => 'other#post_something', as: 'post_something'
Superb! Rails will now attempt to locate the app/views/other/post_something.turbo_stream.erb template at any moment the ‘/other/post_something’ endpoint is reached.
For this, we need to add app/views/other/post_something.turbo_stream.erb template in the rails application.
#CODE
<turbo-stream action="append" target="messages">
<template>
<div id="message_1">This changes the existing message!</div>
</template>
</turbo-stream>
This states that the response will try to append the template of the turbo frame with ID “messages”.
Now change the index.html.erb file in app/views/other paths with the below content.
#CODE
<h1>This is Another page</h1>
<div><%= link_to "Enter to home page", root_path %></div>
<div style="margin-top: 3rem;">
<%= form_with scope: :any, url: post_something_path do |form| %>
<%= form.submit 'Post any message %>
<% end %>
<turbo-frame id="messages">
<div>An empty message</div>
</turbo-frame>
</div>
This action shows that after submitting the response, the Turbo Streams help the developer to append the message, without reloading the page.
Another use case we can test is that rather than appending the message, the developer replaces the message. For that, we need to change the content of app/views/other/post_something.turbo_stream.erb template file and change the value of the action attribute from append to replace and check the changes in the browser.
#CODE
<turbo-stream action="replace" target="messages">
<template>
<div id="message_1">This changes the existing message!</div>
</template>
</turbo-stream>
When we click on Post any message button, the message that appear below that button will get replaced with the message that is mentioned in the app/views/other/post_something.turbo_stream.erb template
There are some cases in an application where JS is needed, therefore to cover those scenarios we require Hotwire JS tool. Hotwire has a JS tool because in some scenarios Turbo-* tools are not sufficient. But as we know that Hotwire is used to reduce the usage of JS in an application, Stimulus considers HTML as the single source of truth. Consider the case where we have to give elements on a page some JavaScript attributes, such as data controller, data-action, and data target. For that, a stimulus controller that can access elements and receive events based on those characteristics will be created.
Make a change in app/views/other/index.html.erb template file in rails application
#CODE
<h1>This is Another page</h1>
<div><%= link_to "Enter to home page", root_path %></div>
<div style="margin-top: 2rem;">
<%= form_with scope: :any, url: post_something_path do |form| %>
<%= form.submit 'Post something' %>
<% end %>
<turbo-frame id="messages">
<div>An empty message</div>
</turbo-frame>
</div>
<div style="margin-top: 2rem;">
<h2>Stimulus</h2>
<div data-controller="hello">
<input data-hello-target="name" type="text">
<button data-action="click->hello#greet">
Greet
</button>
<span data-hello-target="output">
</span>
</div>
</div>
Make changes in the hello_controller.js in path app/JavaScript/controllers and add a stimulus controller in the file, which helps to bring the HTML into life.
#CODE
import { Controller } from "@hotwired/stimulus"
export default class extends Controller {
static targets = [ "name", "output" ]
greet() {
this.outputTarget.textContent =
`Hello, ${this.nameTarget.value}!`
}
}
Go to your browser after making the changes in the code and click on Enter to other page link which will navigate to the localhost:3000/other/index page there you can see the changes implemented by the stimulus controller that is designed to augment your HTML with just enough behavior to make it more responsive.
With just a little bit of work, Turbo and Stimulus together offer a complete answer for applications that are quick and compelling.
Using Rails 7 Hotwire helps to load the pages at a faster speed and allows you to render templates on the server, where you have access to your whole domain model. It is a productive development experience in ROR, without compromising any of the speed or responsiveness associated with SPA.
We hope you were satisfied with our Rails Hotwire tutorial. Write to us at service@bacancy.com for any query that you want to resolve, or if you want us to share a tutorial on your query.
For more such solutions on RoR, check out our Ruby on Rails Tutorials. We will always strive to amaze you and cater to your needs.
Original article source at: https://www.bacancytechnology.com/
1655630160
Install via pip:
$ pip install pytumblr
Install from source:
$ git clone https://github.com/tumblr/pytumblr.git
$ cd pytumblr
$ python setup.py install
A pytumblr.TumblrRestClient
is the object you'll make all of your calls to the Tumblr API through. Creating one is this easy:
client = pytumblr.TumblrRestClient(
'<consumer_key>',
'<consumer_secret>',
'<oauth_token>',
'<oauth_secret>',
)
client.info() # Grabs the current user information
Two easy ways to get your credentials to are:
interactive_console.py
tool (if you already have a consumer key & secret)client.info() # get information about the authenticating user
client.dashboard() # get the dashboard for the authenticating user
client.likes() # get the likes for the authenticating user
client.following() # get the blogs followed by the authenticating user
client.follow('codingjester.tumblr.com') # follow a blog
client.unfollow('codingjester.tumblr.com') # unfollow a blog
client.like(id, reblogkey) # like a post
client.unlike(id, reblogkey) # unlike a post
client.blog_info(blogName) # get information about a blog
client.posts(blogName, **params) # get posts for a blog
client.avatar(blogName) # get the avatar for a blog
client.blog_likes(blogName) # get the likes on a blog
client.followers(blogName) # get the followers of a blog
client.blog_following(blogName) # get the publicly exposed blogs that [blogName] follows
client.queue(blogName) # get the queue for a given blog
client.submission(blogName) # get the submissions for a given blog
Creating posts
PyTumblr lets you create all of the various types that Tumblr supports. When using these types there are a few defaults that are able to be used with any post type.
The default supported types are described below.
We'll show examples throughout of these default examples while showcasing all the specific post types.
Creating a photo post
Creating a photo post supports a bunch of different options plus the described default options * caption - a string, the user supplied caption * link - a string, the "click-through" url for the photo * source - a string, the url for the photo you want to use (use this or the data parameter) * data - a list or string, a list of filepaths or a single file path for multipart file upload
#Creates a photo post using a source URL
client.create_photo(blogName, state="published", tags=["testing", "ok"],
source="https://68.media.tumblr.com/b965fbb2e501610a29d80ffb6fb3e1ad/tumblr_n55vdeTse11rn1906o1_500.jpg")
#Creates a photo post using a local filepath
client.create_photo(blogName, state="queue", tags=["testing", "ok"],
tweet="Woah this is an incredible sweet post [URL]",
data="/Users/johnb/path/to/my/image.jpg")
#Creates a photoset post using several local filepaths
client.create_photo(blogName, state="draft", tags=["jb is cool"], format="markdown",
data=["/Users/johnb/path/to/my/image.jpg", "/Users/johnb/Pictures/kittens.jpg"],
caption="## Mega sweet kittens")
Creating a text post
Creating a text post supports the same options as default and just a two other parameters * title - a string, the optional title for the post. Supports markdown or html * body - a string, the body of the of the post. Supports markdown or html
#Creating a text post
client.create_text(blogName, state="published", slug="testing-text-posts", title="Testing", body="testing1 2 3 4")
Creating a quote post
Creating a quote post supports the same options as default and two other parameter * quote - a string, the full text of the qote. Supports markdown or html * source - a string, the cited source. HTML supported
#Creating a quote post
client.create_quote(blogName, state="queue", quote="I am the Walrus", source="Ringo")
Creating a link post
#Create a link post
client.create_link(blogName, title="I like to search things, you should too.", url="https://duckduckgo.com",
description="Search is pretty cool when a duck does it.")
Creating a chat post
Creating a chat post supports the same options as default and two other parameters * title - a string, the title of the chat post * conversation - a string, the text of the conversation/chat, with diablog labels (no html)
#Create a chat post
chat = """John: Testing can be fun!
Renee: Testing is tedious and so are you.
John: Aw.
"""
client.create_chat(blogName, title="Renee just doesn't understand.", conversation=chat, tags=["renee", "testing"])
Creating an audio post
Creating an audio post allows for all default options and a has 3 other parameters. The only thing to keep in mind while dealing with audio posts is to make sure that you use the external_url parameter or data. You cannot use both at the same time. * caption - a string, the caption for your post * external_url - a string, the url of the site that hosts the audio file * data - a string, the filepath of the audio file you want to upload to Tumblr
#Creating an audio file
client.create_audio(blogName, caption="Rock out.", data="/Users/johnb/Music/my/new/sweet/album.mp3")
#lets use soundcloud!
client.create_audio(blogName, caption="Mega rock out.", external_url="https://soundcloud.com/skrillex/sets/recess")
Creating a video post
Creating a video post allows for all default options and has three other options. Like the other post types, it has some restrictions. You cannot use the embed and data parameters at the same time. * caption - a string, the caption for your post * embed - a string, the HTML embed code for the video * data - a string, the path of the file you want to upload
#Creating an upload from YouTube
client.create_video(blogName, caption="Jon Snow. Mega ridiculous sword.",
embed="http://www.youtube.com/watch?v=40pUYLacrj4")
#Creating a video post from local file
client.create_video(blogName, caption="testing", data="/Users/johnb/testing/ok/blah.mov")
Editing a post
Updating a post requires you knowing what type a post you're updating. You'll be able to supply to the post any of the options given above for updates.
client.edit_post(blogName, id=post_id, type="text", title="Updated")
client.edit_post(blogName, id=post_id, type="photo", data="/Users/johnb/mega/awesome.jpg")
Reblogging a Post
Reblogging a post just requires knowing the post id and the reblog key, which is supplied in the JSON of any post object.
client.reblog(blogName, id=125356, reblog_key="reblog_key")
Deleting a post
Deleting just requires that you own the post and have the post id
client.delete_post(blogName, 123456) # Deletes your post :(
A note on tags: When passing tags, as params, please pass them as a list (not a comma-separated string):
client.create_text(blogName, tags=['hello', 'world'], ...)
Getting notes for a post
In order to get the notes for a post, you need to have the post id and the blog that it is on.
data = client.notes(blogName, id='123456')
The results include a timestamp you can use to make future calls.
data = client.notes(blogName, id='123456', before_timestamp=data["_links"]["next"]["query_params"]["before_timestamp"])
# get posts with a given tag
client.tagged(tag, **params)
This client comes with a nice interactive console to run you through the OAuth process, grab your tokens (and store them for future use).
You'll need pyyaml
installed to run it, but then it's just:
$ python interactive-console.py
and away you go! Tokens are stored in ~/.tumblr
and are also shared by other Tumblr API clients like the Ruby client.
The tests (and coverage reports) are run with nose, like this:
python setup.py test
Author: tumblr
Source Code: https://github.com/tumblr/pytumblr
License: Apache-2.0 license
1669003576
In this Python article, let's learn about Mutable and Immutable in Python.
Mutable is a fancy way of saying that the internal state of the object is changed/mutated. So, the simplest definition is: An object whose internal state can be changed is mutable. On the other hand, immutable doesn’t allow any change in the object once it has been created.
Both of these states are integral to Python data structure. If you want to become more knowledgeable in the entire Python Data Structure, take this free course which covers multiple data structures in Python including tuple data structure which is immutable. You will also receive a certificate on completion which is sure to add value to your portfolio.
Mutable is when something is changeable or has the ability to change. In Python, ‘mutable’ is the ability of objects to change their values. These are often the objects that store a collection of data.
Immutable is the when no change is possible over time. In Python, if the value of an object cannot be changed over time, then it is known as immutable. Once created, the value of these objects is permanent.
Objects of built-in type that are mutable are:
Objects of built-in type that are immutable are:
Object mutability is one of the characteristics that makes Python a dynamically typed language. Though Mutable and Immutable in Python is a very basic concept, it can at times be a little confusing due to the intransitive nature of immutability.
In Python, everything is treated as an object. Every object has these three attributes:
While ID and Type cannot be changed once it’s created, values can be changed for Mutable objects.
Check out this free python certificate course to get started with Python.
I believe, rather than diving deep into the theory aspects of mutable and immutable in Python, a simple code would be the best way to depict what it means in Python. Hence, let us discuss the below code step-by-step:
#Creating a list which contains name of Indian cities
cities = [‘Delhi’, ‘Mumbai’, ‘Kolkata’]
# Printing the elements from the list cities, separated by a comma & space
for city in cities:
print(city, end=’, ’)
Output [1]: Delhi, Mumbai, Kolkata
#Printing the location of the object created in the memory address in hexadecimal format
print(hex(id(cities)))
Output [2]: 0x1691d7de8c8
#Adding a new city to the list cities
cities.append(‘Chennai’)
#Printing the elements from the list cities, separated by a comma & space
for city in cities:
print(city, end=’, ’)
Output [3]: Delhi, Mumbai, Kolkata, Chennai
#Printing the location of the object created in the memory address in hexadecimal format
print(hex(id(cities)))
Output [4]: 0x1691d7de8c8
The above example shows us that we were able to change the internal state of the object ‘cities’ by adding one more city ‘Chennai’ to it, yet, the memory address of the object did not change. This confirms that we did not create a new object, rather, the same object was changed or mutated. Hence, we can say that the object which is a type of list with reference variable name ‘cities’ is a MUTABLE OBJECT.
Let us now discuss the term IMMUTABLE. Considering that we understood what mutable stands for, it is obvious that the definition of immutable will have ‘NOT’ included in it. Here is the simplest definition of immutable– An object whose internal state can NOT be changed is IMMUTABLE.
Again, if you try and concentrate on different error messages, you have encountered, thrown by the respective IDE; you use you would be able to identify the immutable objects in Python. For instance, consider the below code & associated error message with it, while trying to change the value of a Tuple at index 0.
#Creating a Tuple with variable name ‘foo’
foo = (1, 2)
#Changing the index[0] value from 1 to 3
foo[0] = 3
TypeError: 'tuple' object does not support item assignment
Once again, a simple code would be the best way to depict what immutable stands for. Hence, let us discuss the below code step-by-step:
#Creating a Tuple which contains English name of weekdays
weekdays = ‘Sunday’, ‘Monday’, ‘Tuesday’, ‘Wednesday’, ‘Thursday’, ‘Friday’, ‘Saturday’
# Printing the elements of tuple weekdays
print(weekdays)
Output [1]: (‘Sunday’, ‘Monday’, ‘Tuesday’, ‘Wednesday’, ‘Thursday’, ‘Friday’, ‘Saturday’)
#Printing the location of the object created in the memory address in hexadecimal format
print(hex(id(weekdays)))
Output [2]: 0x1691cc35090
#tuples are immutable, so you cannot add new elements, hence, using merge of tuples with the # + operator to add a new imaginary day in the tuple ‘weekdays’
weekdays += ‘Pythonday’,
#Printing the elements of tuple weekdays
print(weekdays)
Output [3]: (‘Sunday’, ‘Monday’, ‘Tuesday’, ‘Wednesday’, ‘Thursday’, ‘Friday’, ‘Saturday’, ‘Pythonday’)
#Printing the location of the object created in the memory address in hexadecimal format
print(hex(id(weekdays)))
Output [4]: 0x1691cc8ad68
This above example shows that we were able to use the same variable name that is referencing an object which is a type of tuple with seven elements in it. However, the ID or the memory location of the old & new tuple is not the same. We were not able to change the internal state of the object ‘weekdays’. The Python program manager created a new object in the memory address and the variable name ‘weekdays’ started referencing the new object with eight elements in it. Hence, we can say that the object which is a type of tuple with reference variable name ‘weekdays’ is an IMMUTABLE OBJECT.
Also Read: Understanding the Exploratory Data Analysis (EDA) in Python
Where can you use mutable and immutable objects:
Mutable objects can be used where you want to allow for any updates. For example, you have a list of employee names in your organizations, and that needs to be updated every time a new member is hired. You can create a mutable list, and it can be updated easily.
Immutability offers a lot of useful applications to different sensitive tasks we do in a network centred environment where we allow for parallel processing. By creating immutable objects, you seal the values and ensure that no threads can invoke overwrite/update to your data. This is also useful in situations where you would like to write a piece of code that cannot be modified. For example, a debug code that attempts to find the value of an immutable object.
Watch outs: Non transitive nature of Immutability:
OK! Now we do understand what mutable & immutable objects in Python are. Let’s go ahead and discuss the combination of these two and explore the possibilities. Let’s discuss, as to how will it behave if you have an immutable object which contains the mutable object(s)? Or vice versa? Let us again use a code to understand this behaviour–
#creating a tuple (immutable object) which contains 2 lists(mutable) as it’s elements
#The elements (lists) contains the name, age & gender
person = (['Ayaan', 5, 'Male'], ['Aaradhya', 8, 'Female'])
#printing the tuple
print(person)
Output [1]: (['Ayaan', 5, 'Male'], ['Aaradhya', 8, 'Female'])
#printing the location of the object created in the memory address in hexadecimal format
print(hex(id(person)))
Output [2]: 0x1691ef47f88
#Changing the age for the 1st element. Selecting 1st element of tuple by using indexing [0] then 2nd element of the list by using indexing [1] and assigning a new value for age as 4
person[0][1] = 4
#printing the updated tuple
print(person)
Output [3]: (['Ayaan', 4, 'Male'], ['Aaradhya', 8, 'Female'])
#printing the location of the object created in the memory address in hexadecimal format
print(hex(id(person)))
Output [4]: 0x1691ef47f88
In the above code, you can see that the object ‘person’ is immutable since it is a type of tuple. However, it has two lists as it’s elements, and we can change the state of lists (lists being mutable). So, here we did not change the object reference inside the Tuple, but the referenced object was mutated.
Also Read: Real-Time Object Detection Using TensorFlow
Same way, let’s explore how it will behave if you have a mutable object which contains an immutable object? Let us again use a code to understand the behaviour–
#creating a list (mutable object) which contains tuples(immutable) as it’s elements
list1 = [(1, 2, 3), (4, 5, 6)]
#printing the list
print(list1)
Output [1]: [(1, 2, 3), (4, 5, 6)]
#printing the location of the object created in the memory address in hexadecimal format
print(hex(id(list1)))
Output [2]: 0x1691d5b13c8
#changing object reference at index 0
list1[0] = (7, 8, 9)
#printing the list
Output [3]: [(7, 8, 9), (4, 5, 6)]
#printing the location of the object created in the memory address in hexadecimal format
print(hex(id(list1)))
Output [4]: 0x1691d5b13c8
As an individual, it completely depends upon you and your requirements as to what kind of data structure you would like to create with a combination of mutable & immutable objects. I hope that this information will help you while deciding the type of object you would like to select going forward.
Before I end our discussion on IMMUTABILITY, allow me to use the word ‘CAVITE’ when we discuss the String and Integers. There is an exception, and you may see some surprising results while checking the truthiness for immutability. For instance:
#creating an object of integer type with value 10 and reference variable name ‘x’
x = 10
#printing the value of ‘x’
print(x)
Output [1]: 10
#Printing the location of the object created in the memory address in hexadecimal format
print(hex(id(x)))
Output [2]: 0x538fb560
#creating an object of integer type with value 10 and reference variable name ‘y’
y = 10
#printing the value of ‘y’
print(y)
Output [3]: 10
#Printing the location of the object created in the memory address in hexadecimal format
print(hex(id(y)))
Output [4]: 0x538fb560
As per our discussion and understanding, so far, the memory address for x & y should have been different, since, 10 is an instance of Integer class which is immutable. However, as shown in the above code, it has the same memory address. This is not something that we expected. It seems that what we have understood and discussed, has an exception as well.
Quick check – Python Data Structures
Tuples are immutable and hence cannot have any changes in them once they are created in Python. This is because they support the same sequence operations as strings. We all know that strings are immutable. The index operator will select an element from a tuple just like in a string. Hence, they are immutable.
Like all, there are exceptions in the immutability in python too. Not all immutable objects are really mutable. This will lead to a lot of doubts in your mind. Let us just take an example to understand this.
Consider a tuple ‘tup’.
Now, if we consider tuple tup = (‘GreatLearning’,[4,3,1,2]) ;
We see that the tuple has elements of different data types. The first element here is a string which as we all know is immutable in nature. The second element is a list which we all know is mutable. Now, we all know that the tuple itself is an immutable data type. It cannot change its contents. But, the list inside it can change its contents. So, the value of the Immutable objects cannot be changed but its constituent objects can. change its value.
Mutable Object | Immutable Object |
State of the object can be modified after it is created. | State of the object can’t be modified once it is created. |
They are not thread safe. | They are thread safe |
Mutable classes are not final. | It is important to make the class final before creating an immutable object. |
list, dictionary, set, user-defined classes.
int, float, decimal, bool, string, tuple, range.
Lists in Python are mutable data types as the elements of the list can be modified, individual elements can be replaced, and the order of elements can be changed even after the list has been created.
(Examples related to lists have been discussed earlier in this blog.)
Tuple and list data structures are very similar, but one big difference between the data types is that lists are mutable, whereas tuples are immutable. The reason for the tuple’s immutability is that once the elements are added to the tuple and the tuple has been created; it remains unchanged.
A programmer would always prefer building a code that can be reused instead of making the whole data object again. Still, even though tuples are immutable, like lists, they can contain any Python object, including mutable objects.
A set is an iterable unordered collection of data type which can be used to perform mathematical operations (like union, intersection, difference etc.). Every element in a set is unique and immutable, i.e. no duplicate values should be there, and the values can’t be changed. However, we can add or remove items from the set as the set itself is mutable.
Strings are not mutable in Python. Strings are a immutable data types which means that its value cannot be updated.
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Original article source at: https://www.mygreatlearning.com
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Superdom
You have dom
. It has all the DOM virtually within it. Use that power:
// Fetch all the page links
let links = dom.a.href;
// Links open in a new tab
dom.a.target = '_blank';
Only for modern browsers
Simply use the CDN via unpkg.com:
<script src="https://unpkg.com/superdom@1"></script>
Or use npm or bower:
npm|bower install superdom --save
It always returns an array with the matched elements. Get all the elements that match the selector:
// Simple element selector into an array
let allLinks = dom.a;
// Loop straight on the selection
dom.a.forEach(link => { ... });
// Combined selector
let importantLinks = dom['a.important'];
There are also some predetermined elements, such as id
, class
and attr
:
// Select HTML Elements by id:
let main = dom.id.main;
// by class:
let buttons = dom.class.button;
// or by attribute:
let targeted = dom.attr.target;
let targeted = dom.attr['target="_blank"'];
Use it as a function or a tagged template literal to generate DOM fragments:
// Not a typo; tagged template literals
let link = dom`<a href="https://google.com/">Google</a>`;
// It is the same as
let link = dom('<a href="https://google.com/">Google</a>');
Delete a piece of the DOM
// Delete all of the elements with the class .google
delete dom.class.google; // Is this an ad-block rule?
You can easily manipulate attributes right from the dom
node. There are some aliases that share the syntax of the attributes such as html
and text
(aliases for innerHTML
and textContent
). There are others that travel through the dom such as parent
(alias for parentNode) and children
. Finally, class
behaves differently as explained below.
The fetching will always return an array with the element for each of the matched nodes (or undefined if not there):
// Retrieve all the urls from the page
let urls = dom.a.href; // #attr-list
// ['https://google.com', 'https://facebook.com/', ...]
// Get an array of the h2 contents (alias of innerHTML)
let h2s = dom.h2.html; // #attr-alias
// ['Level 2 header', 'Another level 2 header', ...]
// Get whether any of the attributes has the value "_blank"
let hasBlank = dom.class.cta.target._blank; // #attr-value
// true/false
You also use these:
innerHTML
): retrieve a list of the htmlstextContent
): retrieve a list of the htmlsparentNode
): travel up one level// Set target="_blank" to all links
dom.a.target = '_blank'; // #attr-set
dom.class.tableofcontents.html = `
<ul class="tableofcontents">
${dom.h2.map(h2 => `
<li>
<a href="#${h2.id}">
${h2.innerHTML}
</a>
</li>
`).join('')}
</ul>
`;
To delete an attribute use the delete
keyword:
// Remove all urls from the page
delete dom.a.href;
// Remove all ids
delete dom.a.id;
It provides an easy way to manipulate the classes.
To retrieve whether a particular class is present or not:
// Get an array with true/false for a single class
let isTest = dom.a.class.test; // #class-one
For a general method to retrieve all classes you can do:
// Get a list of the classes of each matched element
let arrays = dom.a.class; // #class-arrays
// [['important'], ['button', 'cta'], ...]
// If you want a plain list with all of the classes:
let flatten = dom.a.class._flat; // #class-flat
// ['important', 'button', 'cta', ...]
// And if you just want an string with space-separated classes:
let text = dom.a.class._text; // #class-text
// 'important button cta ...'
// Add the class 'test' (different ways)
dom.a.class.test = true; // #class-make-true
dom.a.class = 'test'; // #class-push
// Remove the class 'test'
dom.a.class.test = false; // #class-make-false
Did we say it returns a simple array?
dom.a.forEach(link => link.innerHTML = 'I am a link');
But what an interesting array it is; indeed we are also proxy'ing it so you can manipulate its sub-elements straight from the selector:
// Replace all of the link's html with 'I am a link'
dom.a.html = 'I am a link';
Of course we might want to manipulate them dynamically depending on the current value. Just pass it a function:
// Append ' ^_^' to all of the links in the page
dom.a.html = html => html + ' ^_^';
// Same as this:
dom.a.forEach(link => link.innerHTML = link.innerHTML + ' ^_^');
Note: this won't work
dom.a.html += ' ^_^';
for more than 1 match (for reasons)
Or get into genetics to manipulate the attributes:
dom.a.attr.target = '_blank';
// Only to external sites:
let isOwnPage = el => /^https?\:\/\/mypage\.com/.test(el.getAttribute('href'));
dom.a.attr.target = (prev, i, element) => isOwnPage(element) ? '' : '_blank';
You can also handle and trigger events:
// Handle click events for all <a>
dom.a.on.click = e => ...;
// Trigger click event for all <a>
dom.a.trigger.click;
We are using Jest as a Grunt task for testing. Install Jest and run in the terminal:
grunt watch
Author: franciscop
Source Code: https://github.com/franciscop/superdom
License: MIT license
1626775355
No programming language is pretty much as diverse as Python. It enables building cutting edge applications effortlessly. Developers are as yet investigating the full capability of end-to-end Python development services in various areas.
By areas, we mean FinTech, HealthTech, InsureTech, Cybersecurity, and that's just the beginning. These are New Economy areas, and Python has the ability to serve every one of them. The vast majority of them require massive computational abilities. Python's code is dynamic and powerful - equipped for taking care of the heavy traffic and substantial algorithmic capacities.
Programming advancement is multidimensional today. Endeavor programming requires an intelligent application with AI and ML capacities. Shopper based applications require information examination to convey a superior client experience. Netflix, Trello, and Amazon are genuine instances of such applications. Python assists with building them effortlessly.
Python can do such numerous things that developers can't discover enough reasons to admire it. Python application development isn't restricted to web and enterprise applications. It is exceptionally adaptable and superb for a wide range of uses.
Robust frameworks
Python is known for its tools and frameworks. There's a structure for everything. Django is helpful for building web applications, venture applications, logical applications, and mathematical processing. Flask is another web improvement framework with no conditions.
Web2Py, CherryPy, and Falcon offer incredible capabilities to customize Python development services. A large portion of them are open-source frameworks that allow quick turn of events.
Simple to read and compose
Python has an improved sentence structure - one that is like the English language. New engineers for Python can undoubtedly understand where they stand in the development process. The simplicity of composing allows quick application building.
The motivation behind building Python, as said by its maker Guido Van Rossum, was to empower even beginner engineers to comprehend the programming language. The simple coding likewise permits developers to roll out speedy improvements without getting confused by pointless subtleties.
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Massive community support
Python has a steadily developing community that offers enormous help. From amateurs to specialists, there's everybody. There are a lot of instructional exercises, documentation, and guides accessible for Python web development solutions.
Today, numerous universities start with Python, adding to the quantity of individuals in the community. Frequently, Python designers team up on various tasks and help each other with algorithmic, utilitarian, and application critical thinking.
Progressive applications
Python is the greatest supporter of data science, Machine Learning, and Artificial Intelligence at any enterprise software development company. Its utilization cases in cutting edge applications are the most compelling motivation for its prosperity. Python is the second most well known tool after R for data analytics.
The simplicity of getting sorted out, overseeing, and visualizing information through unique libraries makes it ideal for data based applications. TensorFlow for neural networks and OpenCV for computer vision are two of Python's most well known use cases for Machine learning applications.
Thinking about the advances in programming and innovation, Python is a YES for an assorted scope of utilizations. Game development, web application development services, GUI advancement, ML and AI improvement, Enterprise and customer applications - every one of them uses Python to its full potential.
The disadvantages of Python web improvement arrangements are regularly disregarded by developers and organizations because of the advantages it gives. They focus on quality over speed and performance over blunders. That is the reason it's a good idea to utilize Python for building the applications of the future.
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