Computed value based on another Listenable or Listenables

A class that can be used to derive a value based on data from another Listenable or Listenables.

Usage

The value will be recomputed when the provided listenable notifies the listeners that values have changed.

Simple Example

 final email = ValueNotifier<String>('a');

 // Determine whether or not the email is valid using a (hacky) validator.
 final emailValid = ComputedValueNotifier(
   email,
   () => email.value.contains('@'),
 );

 // The function provided to ComputedValueNotifier is immediately executed,
 // and the computed value is available synchronously.
 print(emailValid.value); // prints 'false'.

 // When the email ValueNotifier is changed, the function will be run again!
 email.value = 'a@b.com';
 print(emailValid.value); // prints 'true'.

Additional information

Thanks to Brian Egan for the gist

Use this package as a library

Depend on it

Run this command:

With Flutter:

 $ flutter pub add computed_value_notifier

This will add a line like this to your package's pubspec.yaml (and run an implicit flutter pub get):

dependencies:
  computed_value_notifier: ^0.0.1

Alternatively, your editor might support or flutter pub get. Check the docs for your editor to learn more.

Import it

Now in your Dart code, you can use:

import 'package:computed_value_notifier/computed_value_notifier.dart'; 

example/lib/main.dart

import 'package:flutter/material.dart';

import 'form_view_model.dart';

void main(List<String> args) {
  runApp(const ExampleApp());
}

class ExampleApp extends StatelessWidget {
  const ExampleApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: Home(),
    );
  }
}

class Home extends StatefulWidget {
  const Home({Key? key}) : super(key: key);

  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {
  late final FormViewModel formViewModel;

  @override
  void initState() {
    super.initState();
    formViewModel = FormViewModel();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Computed Value Notifier Example')),
      body: Center(
        child: FractionallySizedBox(
          widthFactor: 0.8,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              TextField(
                decoration: const InputDecoration(hintText: 'Email'),
                onChanged: (newValue) => formViewModel.email.value = newValue,
              ),
              const SizedBox(height: 10),
              TextField(
                obscureText: true,
                decoration: const InputDecoration(hintText: 'Password'),
                onChanged: (newValue) =>
                    formViewModel.password.value = newValue,
              ),
              const SizedBox(height: 10),
              ValueListenableBuilder<bool>(
                  valueListenable: formViewModel.canLogin,
                  child: const Text('Log In'),
                  builder: (context, canLogin, child) {
                    return ElevatedButton(
                      onPressed: canLogin ? () {} : null,
                      child: child,
                    );
                  })
            ],
          ),
        ),
      ),
    );
  }

  @override
  void dispose() {
    formViewModel.dispose();
    super.dispose();
  }
} 

Download Details:

Author: HosamHasanRamadan

Source Code: https://github.com/HosamHasanRamadan/computed_value_notifier

#flutter 

What is GEEK

Buddha Community

Computed value based on another Listenable or Listenables

Cloud Computing Services | SaaS, PaaS, IaaS - WebClues Infotech

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Thurman  Mills

Thurman Mills

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Cloud Computing Vs Grid Computing

The similarity between cloud computing and grid computing is uncanny. The underlying concepts that make these two inherently different are actually so similar to one and another, which is responsible for creating a lot of confusion. Both cloud and grid computing aims to provide a similar kind of services to a large user base by sharing assets among an enormous pool of clients.

Both of these technologies are obviously network-based and are capable enough to sport multitasking. The availability of multitasking allows the users of either of the two services to use multiple applications at the same time. You are also not limited to the kind of applications that you can use. You are free to choose any number of applications that can accomplish any tasks that you want. Learn more about cloud computing applications.

#cloud computing #cloud computing vs grid computing #grid computing #cloud

Computed value based on another Listenable or Listenables

A class that can be used to derive a value based on data from another Listenable or Listenables.

Usage

The value will be recomputed when the provided listenable notifies the listeners that values have changed.

Simple Example

 final email = ValueNotifier<String>('a');

 // Determine whether or not the email is valid using a (hacky) validator.
 final emailValid = ComputedValueNotifier(
   email,
   () => email.value.contains('@'),
 );

 // The function provided to ComputedValueNotifier is immediately executed,
 // and the computed value is available synchronously.
 print(emailValid.value); // prints 'false'.

 // When the email ValueNotifier is changed, the function will be run again!
 email.value = 'a@b.com';
 print(emailValid.value); // prints 'true'.

Additional information

Thanks to Brian Egan for the gist

Use this package as a library

Depend on it

Run this command:

With Flutter:

 $ flutter pub add computed_value_notifier

This will add a line like this to your package's pubspec.yaml (and run an implicit flutter pub get):

dependencies:
  computed_value_notifier: ^0.0.1

Alternatively, your editor might support or flutter pub get. Check the docs for your editor to learn more.

Import it

Now in your Dart code, you can use:

import 'package:computed_value_notifier/computed_value_notifier.dart'; 

example/lib/main.dart

import 'package:flutter/material.dart';

import 'form_view_model.dart';

void main(List<String> args) {
  runApp(const ExampleApp());
}

class ExampleApp extends StatelessWidget {
  const ExampleApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: Home(),
    );
  }
}

class Home extends StatefulWidget {
  const Home({Key? key}) : super(key: key);

  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {
  late final FormViewModel formViewModel;

  @override
  void initState() {
    super.initState();
    formViewModel = FormViewModel();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Computed Value Notifier Example')),
      body: Center(
        child: FractionallySizedBox(
          widthFactor: 0.8,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              TextField(
                decoration: const InputDecoration(hintText: 'Email'),
                onChanged: (newValue) => formViewModel.email.value = newValue,
              ),
              const SizedBox(height: 10),
              TextField(
                obscureText: true,
                decoration: const InputDecoration(hintText: 'Password'),
                onChanged: (newValue) =>
                    formViewModel.password.value = newValue,
              ),
              const SizedBox(height: 10),
              ValueListenableBuilder<bool>(
                  valueListenable: formViewModel.canLogin,
                  child: const Text('Log In'),
                  builder: (context, canLogin, child) {
                    return ElevatedButton(
                      onPressed: canLogin ? () {} : null,
                      child: child,
                    );
                  })
            ],
          ),
        ),
      ),
    );
  }

  @override
  void dispose() {
    formViewModel.dispose();
    super.dispose();
  }
} 

Download Details:

Author: HosamHasanRamadan

Source Code: https://github.com/HosamHasanRamadan/computed_value_notifier

#flutter 

What is Base Protocol (BASE) | What is BASE token

Base Protocol (BASE) is a token whose price is pegged to the total market cap of all cryptocurrencies at a ratio of 1:1 trillion. BASE allows traders to speculate on the entire crypto industry with one token. The Base Protocol is built on the Ethereum blockchain, integrates a (Chainlink) oracle, and is launching on ((Uniswap)

As cryptocurrency enthusiasts, we’re sometimes divided on which digital assets to buy — bullish on certain projects and bearish on others.

But we all agree on one thing, which is that the overall cryptocurrency industry will achieve long-term growth and future adoption.

The Base Protocol makes it possible to invest with this consensus. BASE allows traders to speculate on the entire industry with one token.

Image for post

The Base Protocol is the world’s first and only tokenized cryptocurrency market tracker. By holding BASE tokens, users can get exposure to the performance of the entire cryptocurrency market. Unlike the index trackers currently operating in the traditional markets, there is no entry or exit fee or brokerage charges.

Index funds have consistently outperformed actively managed mutual funds. Until the launch of BASE, there was no real cryptocurrency market tracker that tracked the performance of the entire digital asset market. BASE will be useful for institutional investors and traders to diversify and hedge their crypto portfolios. BASE will also help new and existing retail investors to take out the guesswork and get exposed to the growth of all current and future digital assets entering the market.

The BASE token’s underlying protocol creates several additional use cases in DeFi, trading, venture capital, hedge funds and many other business sectors.

The Base Protocol mission is simple — to make it easy for everyone to benefit from the performance of the entire cryptocurrency market in a secure, decentralized and future-proof way.

Why BASE?

It’s no doubt that a crypto industry ETF would be a valuable product for investors. But it is very challenging to create such a product through traditional means, as it would be almost impossible to manage portfolio ownership of 5,000+ assets. How would the portfolio manager weigh ownership of each asset as market cap dominance changes? How would they account for newly entering/exiting assets? Who would take on all the associated transaction and custodial fees? There are also various legal limitations that restrict the formation of such an instrument in many countries — and even if it could be formed, it would be a highly centralized product.

By simply pegging price to the total market capitalization of all cryptocurrencies, the Base Protocol cuts through all of these problems. BASE gives holders the same function as a traditional industry ETF without all of the centralized challenges that make such an ETF impossible.

BASE will offer new value for investors in the cryptocurrency ecosystem through an elegantly simple protocol — so valuable and so simple that you might be asking yourself:

How has this not been done before?

The answer is that it wasn’t possible until recently. This project couldn’t be achieved without a robust decentralized blockchain, proven oracle integrations, and new developments in the DeFi space. We founded the Base Protocol to build on these innovations and create BASE; one tokenized asset that represents speculation on all cryptocurrencies.

Vision

We’ve seen that there are many individuals who want to invest in cryptocurrencies, but don’t necessarily understand how they work. While the overview for each different crypto asset can be difficult to understand for a new user, the pitch for BASE is simple: it’s the way to invest in all of those crypto assets simultaneously. In this way, the Base Protocol can become an instrumental force in driving new adoption in the blockchain space.

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In the same way that Bitcoin is the household name of cryptocurrencies, the Base Protocol aims to become the household name for general cryptocurrency investing. BASE’s vision is to become the primary channel of investment for new/existing cryptocurrency traders and institutional investors.

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Julie  Donnelly

Julie Donnelly

1598770012

History of Computing PtI

We learn and know (hopefully) a basic history of the world, particularly major events like the French revolution, the American Civil War, World War I, World War II (wow lots of wars), the Spaceage etc. It is important to understand the concepts of these and many other historical events. Being able to recall the start year or the exact details of how such events unfolded is one thing, but on a human level, it is more important to understand the rationale, lessons and philosophy of major events. Ultimately history teaches us what makes us innately human. Furthermore, understanding history helps us realise the how and why we operate in todayHistory provides the context for today. It makes today seem ‘obvious,’ ‘justifable’ and ‘logical’ given the previous events that unfolded.

So, following this thread of logic, understanding the history of computers should help us understand how we have got to today. A today when computers moderate much of our communication with one another. A today where computers and screens are stared at for many (and often a majority) of our waking hours (especially during Covid). A today where the thought of working, socialising or learning without a computer would be an affront and a disadvantage. Just as major events like World War II and the Cold War have greatly contributed to today’s political and social climate. I would argue computers influence just as much (if not more) of our daily lives.

Therefore it is important for us to understand the evolution of computers to understand where we may be heading in our relationship with computers.

I would like to preface that the following articles outlining the history of computers by saying this is in no way an exhaustive history of the origin of computers. Some major events have been glossed over while other meaningful contributions omitted entirely.

Whilst the thought of history for some may make the eyes automatically glisten over, I will try and make the following series as painless and exciting as possible. While I paint a story of linear progress of computation, this is hindsight bias in action. We like to create a story of history attributing certain importance to some events and not others when in reality as these events were unfolding (and continue to unfold) it was not always obvious what was a gigantic discovery. It is only now with some distance that we can appreciate past event. This means perhaps in ten years this recount will emphasis other features and neglect some of the stories today we find so foundational to computer’s creation.

With all this in mind let’s begin !!


The first computers

Since their inception computers have taken over human work by performing tedious, complex and repetitive tasks. Interestingly, t_he__ word computer initially described humans_!! Initially computers were humans (often women) who were able to perform complex mathematical computations — usually with pen and paper. Often teams would work on the same calculation independently to confirm the end results. It is interesting to note that initally when electronic computers were developed they were referred to as such — electronic computers. With time as electronic computers became more and more pervasive and powerful, it became the human computer that was deemed obsolete and inefficient. The electronic was dropped and now when we discuss computers we think of nothing else besides our gracefull and versalite electronic tools. It is important to keep computer’s mathematical origin in mind as we will see it only further emphasises the never imagined pervasiveness and uses of computers today.

Our story begins with the humble abacus, generally considered the first computer. When researching I was puzzled how an abacus could be considered a computer. Luckily my curiosity was settled by a quick Google search (thank you Google). Google was even able to suggest my search before I completed typing ‘Why is the abacus considered the first computer’! I ended up on trusty Quora where one users: Chrissie Nysen put things simply-“Because it is used to compute things.” Though estimates vary, the abacus is thought to originate in Babylon approximately 5000 years ago. The role of the abacus was to ease in simple mathematical calculations- addition, subtraction, division and multiplication. In this sense, we can consider the abacus as a simple calculator. As farming, produce and populations increased in size, the abacus allowed the educated to more easily manage logistics. After the abacus the first computer, computer’s evolution remained dormant for some time……

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