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How to Use Static Analyzers in Python
In this Python article, we will learn about How to Use Static Analyzers in Python. What is static analysis in Python? Which Python static analysis tools should. Static analyzers are tools that help you check your code without really running your code. The most basic form of static analyzers is the syntax highlighters in your favorite editors. If you need to compile your code (say, in C++), your compiler, such as LLVM, may also provide some static analyzer functions to warn you about potential issues (e.g., mistaken assignment “
=” for equality “==” in C++). In Python, we have some tools to identify potential errors or point out violations of coding standards.
After finishing this tutorial, you will learn some of these tools. Specifically,
- What can the tools Pylint, Flake8, and mypy do?
- What are coding style violations?
- How can we use type hints to help analyzers identify potential bugs?
Kick-start your project with my new book Python for Machine Learning, including step-by-step tutorials and the Python source code files for all examples.
Let’s get started.
Overview
This tutorial is in three parts; they are:
- Introduction to Pylint
- Introduction to Flake8
- Introduction to mypy
Pylint
Lint was the name of a static analyzer for C created a long time ago. Pylint borrowed its name and is one of the most widely used static analyzers. It is available as a Python package, and we can install it with pip:
$ pip install pylintThen we have the command pylint available in our system.
Pylint can check one script or the entire directory. For example, if we have the following script saved as lenet5-notworking.py:
import numpy as np
import h5py
import tensorflow as tf
from tensorflow.keras.datasets import mnist
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Conv2D, Dense, AveragePooling2D, Dropout, Flatten
from tensorflow.keras.utils import to_categorical
from tensorflow.keras.callbacks import EarlyStopping
# Load MNIST digits
(X_train, Y_train), (X_test, Y_test) = mnist.load_data()
# Reshape data to (n_samples, height, wiedth, n_channel)
X_train = np.expand_dims(X_train, axis=3).astype("float32")
X_test = np.expand_dims(X_test, axis=3).astype("float32")
# One-hot encode the output
y_train = to_categorical(y_train)
y_test = to_categorical(y_test)
# LeNet5 model
def createmodel(activation):
model = Sequential([
Conv2D(6, (5,5), input_shape=(28,28,1), padding="same", activation=activation),
AveragePooling2D((2,2), strides=2),
Conv2D(16, (5,5), activation=activation),
AveragePooling2D((2,2), strides=2),
Conv2D(120, (5,5), activation=activation),
Flatten(),
Dense(84, activation=activation),
Dense(10, activation="softmax")
])
return model
# Train the model
model = createmodel(tanh)
model.compile(loss="categorical_crossentropy", optimizer="adam", metrics=["accuracy"])
earlystopping = EarlyStopping(monitor="val_loss", patience=4, restore_best_weights=True)
model.fit(X_train, y_train, validation_data=(X_test, y_test), epochs=100, batch_size=32, callbacks=[earlystopping])
# Evaluate the model
print(model.evaluate(X_test, y_test, verbose=0))
model.save("lenet5.h5")We can ask Pylint to tell us how good our code is before even running it:
$ pylint lenet5-notworking.pyThe output is as follows:
************* Module lenet5-notworking
lenet5-notworking.py:39:0: C0301: Line too long (115/100) (line-too-long)
lenet5-notworking.py:1:0: C0103: Module name "lenet5-notworking" doesn't conform to snake_case naming style (invalid-name)
lenet5-notworking.py:1:0: C0114: Missing module docstring (missing-module-docstring)
lenet5-notworking.py:4:0: E0611: No name 'datasets' in module 'LazyLoader' (no-name-in-module)
lenet5-notworking.py:5:0: E0611: No name 'models' in module 'LazyLoader' (no-name-in-module)
lenet5-notworking.py:6:0: E0611: No name 'layers' in module 'LazyLoader' (no-name-in-module)
lenet5-notworking.py:7:0: E0611: No name 'utils' in module 'LazyLoader' (no-name-in-module)
lenet5-notworking.py:8:0: E0611: No name 'callbacks' in module 'LazyLoader' (no-name-in-module)
lenet5-notworking.py:18:25: E0601: Using variable 'y_train' before assignment (used-before-assignment)
lenet5-notworking.py:19:24: E0601: Using variable 'y_test' before assignment (used-before-assignment)
lenet5-notworking.py:23:4: W0621: Redefining name 'model' from outer scope (line 36) (redefined-outer-name)
lenet5-notworking.py:22:0: C0116: Missing function or method docstring (missing-function-docstring)
lenet5-notworking.py:36:20: E0602: Undefined variable 'tanh' (undefined-variable)
lenet5-notworking.py:2:0: W0611: Unused import h5py (unused-import)
lenet5-notworking.py:3:0: W0611: Unused tensorflow imported as tf (unused-import)
lenet5-notworking.py:6:0: W0611: Unused Dropout imported from tensorflow.keras.layers (unused-import)
-------------------------------------
Your code has been rated at -11.82/10If you provide the root directory of a module to Pylint, all components of the module will be checked by Pylint. In that case, you will see the path of different files at the beginning of each line.
There are several things to note here. First, the complaints from Pylint are in different categories. Most commonly we would see issues on convention (i.e., a matter of style), warnings (i.e., the code may run in a sense not consistent with what you intended to do), and error (i.e., the code may fail to run and throw exceptions). They are identified by the code such as E0601, where the first letter is the category.
Pylint may give false positives. In the example above, we see Pylint flagged the import from tensorflow.keras.datasets as an error. It is caused by an optimization in the Tensorflow package that not everything would be scanned and loaded by Python when we import Tensorflow, but a LazyLoader is created to help load only the necessary part of a large package. This saves significant time in starting the program, but it also confuses Pylint in that we seem to import something that doesn’t exist.
Furthermore, one of the key feature of Pylint is to help us make our code align with the PEP8 coding style. When we define a function without a docstring, for instance, Pylint will complain that we didn’t follow the coding convention even if the code is not doing anything wrong.
But the most important use of Pylint is to help us identify potential issues. For example, we misspelled y_train as Y_train with an uppercase Y. Pylint will tell us that we are using a variable without assigning any value to it. It is not straightforwardly telling us what went wrong, but it definitely points us to the right spot to proofread our code. Similarly, when we define the variable model on line 23, Pylint told us that there is a variable of the same name at the outer scope. Hence the reference to model later on may not be what we were thinking. Similarly, unused imports may be just that we misspelled the name of the modules.
All these are hints provided by Pylint. We still have to use our judgement to correct our code (or ignore Pylint’s complaints).
But if you know what Pylint should stop complaining about, you can request to ignore those. For example, we know the import statements are fine, so we can invoke Pylint with:
$ pylint -d E0611 lenet5-notworking.pyNow, all errors of code E0611 will be ignored by Pylint. You can disable multiple codes by a comma-separated list, e.g.,
$ pylint -d E0611,C0301 lenet5-notworking.pyIf you want to disable some issues on only a specific line or a specific part of the code, you can put special comments to your code, as follows:
...
from tensorflow.keras.datasets import mnist # pylint: disable=no-name-in-module
from tensorflow.keras.models import Sequential # pylint: disable=E0611
from tensorflow.keras.layers import Conv2D, Dense, AveragePooling2D, Dropout, Flatten
from tensorflow.keras.utils import to_categoricalThe magic keyword pylint: will introduce Pylint-specific instructions. The code E0611 and the name no-name-in-module are the same. In the example above, Pylint will complain about the last two import statements but not the first two because of those special comments.
Flake8
The tool Flake8 is indeed a wrapper over PyFlakes, McCabe, and pycodestyle. When you install flake8 with:
$ pip install flake8you will install all these dependencies.
Similar to Pylint, we have the command flake8 after installing this package, and we can pass in a script or a directory for analysis. But the focus of Flake8 is inclined toward coding style. Hence we would see the following output for the same code as above:
$ flake8 lenet5-notworking.py
lenet5-notworking.py:2:1: F401 'h5py' imported but unused
lenet5-notworking.py:3:1: F401 'tensorflow as tf' imported but unused
lenet5-notworking.py:6:1: F401 'tensorflow.keras.layers.Dropout' imported but unused
lenet5-notworking.py:6:80: E501 line too long (85 > 79 characters)
lenet5-notworking.py:18:26: F821 undefined name 'y_train'
lenet5-notworking.py:19:25: F821 undefined name 'y_test'
lenet5-notworking.py:22:1: E302 expected 2 blank lines, found 1
lenet5-notworking.py:24:21: E231 missing whitespace after ','
lenet5-notworking.py:24:41: E231 missing whitespace after ','
lenet5-notworking.py:24:44: E231 missing whitespace after ','
lenet5-notworking.py:24:80: E501 line too long (87 > 79 characters)
lenet5-notworking.py:25:28: E231 missing whitespace after ','
lenet5-notworking.py:26:22: E231 missing whitespace after ','
lenet5-notworking.py:27:28: E231 missing whitespace after ','
lenet5-notworking.py:28:23: E231 missing whitespace after ','
lenet5-notworking.py:36:1: E305 expected 2 blank lines after class or function definition, found 1
lenet5-notworking.py:36:21: F821 undefined name 'tanh'
lenet5-notworking.py:37:80: E501 line too long (86 > 79 characters)
lenet5-notworking.py:38:80: E501 line too long (88 > 79 characters)
lenet5-notworking.py:39:80: E501 line too long (115 > 79 characters)The error codes beginning with letter E are from pycodestyle, and those beginning with letter F are from PyFlakes. We can see it complains about coding style issues such as the use of (5,5) for not having a space after the comma. We can also see it can identify the use of variables before assignment. But it does not catch some code smells such as the function createmodel()that reuses the variable model that was already defined in outer scope.
Similar to Pylint, we can also ask Flake8 to ignore some complaints. For example,
flake8 --ignore E501,E231 lenet5-notworking.pyThose lines will not be printed in the output:
lenet5-notworking.py:2:1: F401 'h5py' imported but unused
lenet5-notworking.py:3:1: F401 'tensorflow as tf' imported but unused
lenet5-notworking.py:6:1: F401 'tensorflow.keras.layers.Dropout' imported but unused
lenet5-notworking.py:18:26: F821 undefined name 'y_train'
lenet5-notworking.py:19:25: F821 undefined name 'y_test'
lenet5-notworking.py:22:1: E302 expected 2 blank lines, found 1
lenet5-notworking.py:36:1: E305 expected 2 blank lines after class or function definition, found 1
lenet5-notworking.py:36:21: F821 undefined name 'tanh'We can also use magic comments to disable some complaints, e.g.,
...
import tensorflow as tf # noqa: F401
from tensorflow.keras.datasets import mnist
from tensorflow.keras.models import SequentialFlake8 will look for the comment # noqa: to skip some complaints on those particular lines.
Mypy
Python is not a typed language so, unlike C or Java, you do not need to declare the types of some functions or variables before use. But lately, Python has introduced type hint notation, so we can specify what type a function or variable intended to be without enforcing its compliance like a typed language.
One of the biggest benefits of using type hints in Python is to provide additional information for static analyzers to check. Mypy is the tool that can understand type hints. Even without type hints, Mypy can still provide complaints similar to Pylint and Flake8.
We can install Mypy from PyPI:
$ pip install mypyThen the example above can be provided to the mypy command:
$ mypy lenet5-notworking.py
lenet5-notworking.py:2: error: Skipping analyzing "h5py": module is installed, but missing library stubs or py.typed marker
lenet5-notworking.py:2: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
lenet5-notworking.py:3: error: Skipping analyzing "tensorflow": module is installed, but missing library stubs or py.typed marker
lenet5-notworking.py:4: error: Skipping analyzing "tensorflow.keras.datasets": module is installed, but missing library stubs or py.typed marker
lenet5-notworking.py:5: error: Skipping analyzing "tensorflow.keras.models": module is installed, but missing library stubs or py.typed marker
lenet5-notworking.py:6: error: Skipping analyzing "tensorflow.keras.layers": module is installed, but missing library stubs or py.typed marker
lenet5-notworking.py:7: error: Skipping analyzing "tensorflow.keras.utils": module is installed, but missing library stubs or py.typed marker
lenet5-notworking.py:8: error: Skipping analyzing "tensorflow.keras.callbacks": module is installed, but missing library stubs or py.typed marker
lenet5-notworking.py:18: error: Cannot determine type of "y_train"
lenet5-notworking.py:19: error: Cannot determine type of "y_test"
lenet5-notworking.py:36: error: Name "tanh" is not defined
Found 10 errors in 1 file (checked 1 source file)We see similar errors as Pylint above, although sometimes not as precise (e.g., the issue with the variable y_train). However we see one characteristic of mypy above: It expects all libraries we used to come with a stub so the type checking can be done. This is because type hints are optional. In case the code from a library does not provide type hints, the code can still work, but mypy cannot verify. Some of the libraries have typing stubs available that enables mypy to check them better.
Let’s consider another example:
import h5py
def dumphdf5(filename: str) -> int:
"""Open a HDF5 file and print all the dataset and attributes stored
Args:
filename: The HDF5 filename
Returns:
Number of dataset found in the HDF5 file
"""
count: int = 0
def recur_dump(obj) -> None:
print(f"{obj.name} ({type(obj).__name__})")
if obj.attrs.keys():
print("\tAttribs:")
for key in obj.attrs.keys():
print(f"\t\t{key}: {obj.attrs[key]}")
if isinstance(obj, h5py.Group):
# Group has key-value pairs
for key, value in obj.items():
recur_dump(value)
elif isinstance(obj, h5py.Dataset):
count += 1
print(obj[()])
with h5py.File(filename) as obj:
recur_dump(obj)
print(f"{count} dataset found")
with open("my_model.h5") as fp:
dumphdf5(fp)This program is supposed to load a HDF5 file (such as a Keras model) and print every attribute and data stored in it. We used the h5py module (which does not have a typing stub, and hence mypy cannot identify the types it used), but we added type hints to the function we defined, dumphdf5(). This function expects the filename of a HDF5 file and prints everything stored inside. At the end, the number of datasets stored will be returned.
When we save this script into dumphdf5.py and pass it into mypy, we will see the following:
$ mypy dumphdf5.py
dumphdf5.py:1: error: Skipping analyzing "h5py": module is installed, but missing library stubs or py.typed marker
dumphdf5.py:1: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
dumphdf5.py:3: error: Missing return statement
dumphdf5.py:33: error: Argument 1 to "dumphdf5" has incompatible type "TextIO"; expected "str"
Found 3 errors in 1 file (checked 1 source file)We misused our function so that an opened file object is passed into dumphdf5() instead of just the filename (as a string). Mypy can identify this error. We also declared that the function should return an integer, but we didn’t have the return statement in the function.
However, there is one more error in this code that mypy didn’t identify. Namely, the use of the variable count in the inner function recur_dump() should be declared nonlocal because it is defined out of scope. This error can be caught by Pylint and Flake8, but mypy missed it.
The following is the complete, corrected code with no more errors. Note that we added the magic comment “# type: ignore” at the first line to mute the typing stubs warning from mypy:
import h5py # type: ignore
def dumphdf5(filename: str) -> int:
"""Open a HDF5 file and print all the dataset and attributes stored
Args:
filename: The HDF5 filename
Returns:
Number of dataset found in the HDF5 file
"""
count: int = 0
def recur_dump(obj) -> None:
nonlocal count
print(f"{obj.name} ({type(obj).__name__})")
if obj.attrs.keys():
print("\tAttribs:")
for key in obj.attrs.keys():
print(f"\t\t{key}: {obj.attrs[key]}")
if isinstance(obj, h5py.Group):
# Group has key-value pairs
for key, value in obj.items():
recur_dump(value)
elif isinstance(obj, h5py.Dataset):
count += 1
print(obj[()])
with h5py.File(filename) as obj:
recur_dump(obj)
print(f"{count} dataset found")
return count
dumphdf5("my_model.h5")In conclusion, the three tools we introduced above can be complementary to each other. You may consider to run all of them to look for any possible bugs in your code or improve the coding style. Each tool allows some configuration, either from the command line or from a config file, to customize for your needs (e.g., how long a line should be too long to deserve a warning?). Using a static analyzer is also a way to help yourself develop better programming skills.
Original article sourced at: https://machinelearningmastery.com
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Pdf2gerb: Perl Script Converts PDF Files to Gerber format
pdf2gerb
Perl script converts PDF files to Gerber format
Pdf2Gerb generates Gerber 274X photoplotting and Excellon drill files from PDFs of a PCB. Up to three PDFs are used: the top copper layer, the bottom copper layer (for 2-sided PCBs), and an optional silk screen layer. The PDFs can be created directly from any PDF drawing software, or a PDF print driver can be used to capture the Print output if the drawing software does not directly support output to PDF.
The general workflow is as follows:
- Design the PCB using your favorite CAD or drawing software.
- Print the top and bottom copper and top silk screen layers to a PDF file.
- Run Pdf2Gerb on the PDFs to create Gerber and Excellon files.
- Use a Gerber viewer to double-check the output against the original PCB design.
- Make adjustments as needed.
- Submit the files to a PCB manufacturer.
Please note that Pdf2Gerb does NOT perform DRC (Design Rule Checks), as these will vary according to individual PCB manufacturer conventions and capabilities. Also note that Pdf2Gerb is not perfect, so the output files must always be checked before submitting them. As of version 1.6, Pdf2Gerb supports most PCB elements, such as round and square pads, round holes, traces, SMD pads, ground planes, no-fill areas, and panelization. However, because it interprets the graphical output of a Print function, there are limitations in what it can recognize (or there may be bugs).
See docs/Pdf2Gerb.pdf for install/setup, config, usage, and other info.
pdf2gerb_cfg.pm
#Pdf2Gerb config settings:
#Put this file in same folder/directory as pdf2gerb.pl itself (global settings),
#or copy to another folder/directory with PDFs if you want PCB-specific settings.
#There is only one user of this file, so we don't need a custom package or namespace.
#NOTE: all constants defined in here will be added to main namespace.
#package pdf2gerb_cfg;
use strict; #trap undef vars (easier debug)
use warnings; #other useful info (easier debug)
##############################################################################################
#configurable settings:
#change values here instead of in main pfg2gerb.pl file
use constant WANT_COLORS => ($^O !~ m/Win/); #ANSI colors no worky on Windows? this must be set < first DebugPrint() call
#just a little warning; set realistic expectations:
#DebugPrint("${\(CYAN)}Pdf2Gerb.pl ${\(VERSION)}, $^O O/S\n${\(YELLOW)}${\(BOLD)}${\(ITALIC)}This is EXPERIMENTAL software. \nGerber files MAY CONTAIN ERRORS. Please CHECK them before fabrication!${\(RESET)}", 0); #if WANT_DEBUG
use constant METRIC => FALSE; #set to TRUE for metric units (only affect final numbers in output files, not internal arithmetic)
use constant APERTURE_LIMIT => 0; #34; #max #apertures to use; generate warnings if too many apertures are used (0 to not check)
use constant DRILL_FMT => '2.4'; #'2.3'; #'2.4' is the default for PCB fab; change to '2.3' for CNC
use constant WANT_DEBUG => 0; #10; #level of debug wanted; higher == more, lower == less, 0 == none
use constant GERBER_DEBUG => 0; #level of debug to include in Gerber file; DON'T USE FOR FABRICATION
use constant WANT_STREAMS => FALSE; #TRUE; #save decompressed streams to files (for debug)
use constant WANT_ALLINPUT => FALSE; #TRUE; #save entire input stream (for debug ONLY)
#DebugPrint(sprintf("${\(CYAN)}DEBUG: stdout %d, gerber %d, want streams? %d, all input? %d, O/S: $^O, Perl: $]${\(RESET)}\n", WANT_DEBUG, GERBER_DEBUG, WANT_STREAMS, WANT_ALLINPUT), 1);
#DebugPrint(sprintf("max int = %d, min int = %d\n", MAXINT, MININT), 1);
#define standard trace and pad sizes to reduce scaling or PDF rendering errors:
#This avoids weird aperture settings and replaces them with more standardized values.
#(I'm not sure how photoplotters handle strange sizes).
#Fewer choices here gives more accurate mapping in the final Gerber files.
#units are in inches
use constant TOOL_SIZES => #add more as desired
(
#round or square pads (> 0) and drills (< 0):
.010, -.001, #tiny pads for SMD; dummy drill size (too small for practical use, but needed so StandardTool will use this entry)
.031, -.014, #used for vias
.041, -.020, #smallest non-filled plated hole
.051, -.025,
.056, -.029, #useful for IC pins
.070, -.033,
.075, -.040, #heavier leads
# .090, -.043, #NOTE: 600 dpi is not high enough resolution to reliably distinguish between .043" and .046", so choose 1 of the 2 here
.100, -.046,
.115, -.052,
.130, -.061,
.140, -.067,
.150, -.079,
.175, -.088,
.190, -.093,
.200, -.100,
.220, -.110,
.160, -.125, #useful for mounting holes
#some additional pad sizes without holes (repeat a previous hole size if you just want the pad size):
.090, -.040, #want a .090 pad option, but use dummy hole size
.065, -.040, #.065 x .065 rect pad
.035, -.040, #.035 x .065 rect pad
#traces:
.001, #too thin for real traces; use only for board outlines
.006, #minimum real trace width; mainly used for text
.008, #mainly used for mid-sized text, not traces
.010, #minimum recommended trace width for low-current signals
.012,
.015, #moderate low-voltage current
.020, #heavier trace for power, ground (even if a lighter one is adequate)
.025,
.030, #heavy-current traces; be careful with these ones!
.040,
.050,
.060,
.080,
.100,
.120,
);
#Areas larger than the values below will be filled with parallel lines:
#This cuts down on the number of aperture sizes used.
#Set to 0 to always use an aperture or drill, regardless of size.
use constant { MAX_APERTURE => max((TOOL_SIZES)) + .004, MAX_DRILL => -min((TOOL_SIZES)) + .004 }; #max aperture and drill sizes (plus a little tolerance)
#DebugPrint(sprintf("using %d standard tool sizes: %s, max aper %.3f, max drill %.3f\n", scalar((TOOL_SIZES)), join(", ", (TOOL_SIZES)), MAX_APERTURE, MAX_DRILL), 1);
#NOTE: Compare the PDF to the original CAD file to check the accuracy of the PDF rendering and parsing!
#for example, the CAD software I used generated the following circles for holes:
#CAD hole size: parsed PDF diameter: error:
# .014 .016 +.002
# .020 .02267 +.00267
# .025 .026 +.001
# .029 .03167 +.00267
# .033 .036 +.003
# .040 .04267 +.00267
#This was usually ~ .002" - .003" too big compared to the hole as displayed in the CAD software.
#To compensate for PDF rendering errors (either during CAD Print function or PDF parsing logic), adjust the values below as needed.
#units are pixels; for example, a value of 2.4 at 600 dpi = .0004 inch, 2 at 600 dpi = .0033"
use constant
{
HOLE_ADJUST => -0.004 * 600, #-2.6, #holes seemed to be slightly oversized (by .002" - .004"), so shrink them a little
RNDPAD_ADJUST => -0.003 * 600, #-2, #-2.4, #round pads seemed to be slightly oversized, so shrink them a little
SQRPAD_ADJUST => +0.001 * 600, #+.5, #square pads are sometimes too small by .00067, so bump them up a little
RECTPAD_ADJUST => 0, #(pixels) rectangular pads seem to be okay? (not tested much)
TRACE_ADJUST => 0, #(pixels) traces seemed to be okay?
REDUCE_TOLERANCE => .001, #(inches) allow this much variation when reducing circles and rects
};
#Also, my CAD's Print function or the PDF print driver I used was a little off for circles, so define some additional adjustment values here:
#Values are added to X/Y coordinates; units are pixels; for example, a value of 1 at 600 dpi would be ~= .002 inch
use constant
{
CIRCLE_ADJUST_MINX => 0,
CIRCLE_ADJUST_MINY => -0.001 * 600, #-1, #circles were a little too high, so nudge them a little lower
CIRCLE_ADJUST_MAXX => +0.001 * 600, #+1, #circles were a little too far to the left, so nudge them a little to the right
CIRCLE_ADJUST_MAXY => 0,
SUBST_CIRCLE_CLIPRECT => FALSE, #generate circle and substitute for clip rects (to compensate for the way some CAD software draws circles)
WANT_CLIPRECT => TRUE, #FALSE, #AI doesn't need clip rect at all? should be on normally?
RECT_COMPLETION => FALSE, #TRUE, #fill in 4th side of rect when 3 sides found
};
#allow .012 clearance around pads for solder mask:
#This value effectively adjusts pad sizes in the TOOL_SIZES list above (only for solder mask layers).
use constant SOLDER_MARGIN => +.012; #units are inches
#line join/cap styles:
use constant
{
CAP_NONE => 0, #butt (none); line is exact length
CAP_ROUND => 1, #round cap/join; line overhangs by a semi-circle at either end
CAP_SQUARE => 2, #square cap/join; line overhangs by a half square on either end
CAP_OVERRIDE => FALSE, #cap style overrides drawing logic
};
#number of elements in each shape type:
use constant
{
RECT_SHAPELEN => 6, #x0, y0, x1, y1, count, "rect" (start, end corners)
LINE_SHAPELEN => 6, #x0, y0, x1, y1, count, "line" (line seg)
CURVE_SHAPELEN => 10, #xstart, ystart, x0, y0, x1, y1, xend, yend, count, "curve" (bezier 2 points)
CIRCLE_SHAPELEN => 5, #x, y, 5, count, "circle" (center + radius)
};
#const my %SHAPELEN =
#Readonly my %SHAPELEN =>
our %SHAPELEN =
(
rect => RECT_SHAPELEN,
line => LINE_SHAPELEN,
curve => CURVE_SHAPELEN,
circle => CIRCLE_SHAPELEN,
);
#panelization:
#This will repeat the entire body the number of times indicated along the X or Y axes (files grow accordingly).
#Display elements that overhang PCB boundary can be squashed or left as-is (typically text or other silk screen markings).
#Set "overhangs" TRUE to allow overhangs, FALSE to truncate them.
#xpad and ypad allow margins to be added around outer edge of panelized PCB.
use constant PANELIZE => {'x' => 1, 'y' => 1, 'xpad' => 0, 'ypad' => 0, 'overhangs' => TRUE}; #number of times to repeat in X and Y directions
# Set this to 1 if you need TurboCAD support.
#$turboCAD = FALSE; #is this still needed as an option?
#CIRCAD pad generation uses an appropriate aperture, then moves it (stroke) "a little" - we use this to find pads and distinguish them from PCB holes.
use constant PAD_STROKE => 0.3; #0.0005 * 600; #units are pixels
#convert very short traces to pads or holes:
use constant TRACE_MINLEN => .001; #units are inches
#use constant ALWAYS_XY => TRUE; #FALSE; #force XY even if X or Y doesn't change; NOTE: needs to be TRUE for all pads to show in FlatCAM and ViewPlot
use constant REMOVE_POLARITY => FALSE; #TRUE; #set to remove subtractive (negative) polarity; NOTE: must be FALSE for ground planes
#PDF uses "points", each point = 1/72 inch
#combined with a PDF scale factor of .12, this gives 600 dpi resolution (1/72 * .12 = 600 dpi)
use constant INCHES_PER_POINT => 1/72; #0.0138888889; #multiply point-size by this to get inches
# The precision used when computing a bezier curve. Higher numbers are more precise but slower (and generate larger files).
#$bezierPrecision = 100;
use constant BEZIER_PRECISION => 36; #100; #use const; reduced for faster rendering (mainly used for silk screen and thermal pads)
# Ground planes and silk screen or larger copper rectangles or circles are filled line-by-line using this resolution.
use constant FILL_WIDTH => .01; #fill at most 0.01 inch at a time
# The max number of characters to read into memory
use constant MAX_BYTES => 10 * M; #bumped up to 10 MB, use const
use constant DUP_DRILL1 => TRUE; #FALSE; #kludge: ViewPlot doesn't load drill files that are too small so duplicate first tool
my $runtime = time(); #Time::HiRes::gettimeofday(); #measure my execution time
print STDERR "Loaded config settings from '${\(__FILE__)}'.\n";
1; #last value must be truthful to indicate successful load
#############################################################################################
#junk/experiment:
#use Package::Constants;
#use Exporter qw(import); #https://perldoc.perl.org/Exporter.html
#my $caller = "pdf2gerb::";
#sub cfg
#{
# my $proto = shift;
# my $class = ref($proto) || $proto;
# my $settings =
# {
# $WANT_DEBUG => 990, #10; #level of debug wanted; higher == more, lower == less, 0 == none
# };
# bless($settings, $class);
# return $settings;
#}
#use constant HELLO => "hi there2"; #"main::HELLO" => "hi there";
#use constant GOODBYE => 14; #"main::GOODBYE" => 12;
#print STDERR "read cfg file\n";
#our @EXPORT_OK = Package::Constants->list(__PACKAGE__); #https://www.perlmonks.org/?node_id=1072691; NOTE: "_OK" skips short/common names
#print STDERR scalar(@EXPORT_OK) . " consts exported:\n";
#foreach(@EXPORT_OK) { print STDERR "$_\n"; }
#my $val = main::thing("xyz");
#print STDERR "caller gave me $val\n";
#foreach my $arg (@ARGV) { print STDERR "arg $arg\n"; }Download Details:
Author: swannman
Source Code: https://github.com/swannman/pdf2gerb
License: GPL-3.0 license
1626775355
Why use Python for Software Development
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.
5 Reasons to Utilize Python for Programming Web Apps
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.
Utilized by the best
Alright - Python isn't simply one more programming language. It should have something, which is the reason the business giants use it. Furthermore, that too for different purposes. Developers at Google use Python to assemble framework organization systems, parallel information pusher, code audit, testing and QA, and substantially more. Netflix utilizes Python web development services for its recommendation algorithm and media player.
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.
Summary
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.
#python development services #python development company #python app development #python development #python in web development #python software development
1604008800
Static Code Analysis: What It Is? How to Use It?
Static code analysis refers to the technique of approximating the runtime behavior of a program. In other words, it is the process of predicting the output of a program without actually executing it.
Lately, however, the term “Static Code Analysis” is more commonly used to refer to one of the applications of this technique rather than the technique itself — program comprehension — understanding the program and detecting issues in it (anything from syntax errors to type mismatches, performance hogs likely bugs, security loopholes, etc.). This is the usage we’d be referring to throughout this post.
“The refinement of techniques for the prompt discovery of error serves as well as any other as a hallmark of what we mean by science.”
- J. Robert Oppenheimer
Outline
We cover a lot of ground in this post. The aim is to build an understanding of static code analysis and to equip you with the basic theory, and the right tools so that you can write analyzers on your own.
We start our journey with laying down the essential parts of the pipeline which a compiler follows to understand what a piece of code does. We learn where to tap points in this pipeline to plug in our analyzers and extract meaningful information. In the latter half, we get our feet wet, and write four such static analyzers, completely from scratch, in Python.
Note that although the ideas here are discussed in light of Python, static code analyzers across all programming languages are carved out along similar lines. We chose Python because of the availability of an easy to use ast module, and wide adoption of the language itself.
How does it all work?
Before a computer can finally “understand” and execute a piece of code, it goes through a series of complicated transformations:
As you can see in the diagram (go ahead, zoom it!), the static analyzers feed on the output of these stages. To be able to better understand the static analysis techniques, let’s look at each of these steps in some more detail:
Scanning
The first thing that a compiler does when trying to understand a piece of code is to break it down into smaller chunks, also known as tokens. Tokens are akin to what words are in a language.
A token might consist of either a single character, like (, or literals (like integers, strings, e.g., 7, Bob, etc.), or reserved keywords of that language (e.g, def in Python). Characters which do not contribute towards the semantics of a program, like trailing whitespace, comments, etc. are often discarded by the scanner.
Python provides the tokenize module in its standard library to let you play around with tokens:
Python
1
import io
2
import tokenize
3
4
code = b"color = input('Enter your favourite color: ')"
5
6
for token in tokenize.tokenize(io.BytesIO(code).readline):
7
print(token)
Python
1
TokenInfo(type=62 (ENCODING), string='utf-8')
2
TokenInfo(type=1 (NAME), string='color')
3
TokenInfo(type=54 (OP), string='=')
4
TokenInfo(type=1 (NAME), string='input')
5
TokenInfo(type=54 (OP), string='(')
6
TokenInfo(type=3 (STRING), string="'Enter your favourite color: '")
7
TokenInfo(type=54 (OP), string=')')
8
TokenInfo(type=4 (NEWLINE), string='')
9
TokenInfo(type=0 (ENDMARKER), string='')
(Note that for the sake of readability, I’ve omitted a few columns from the result above — metadata like starting index, ending index, a copy of the line on which a token occurs, etc.)
#code quality #code review #static analysis #static code analysis #code analysis #static analysis tools #code review tips #static code analyzer #static code analysis tool #static analyzer
1597751700
How To Compare Tesla and Ford Company By Using Magic Methods in Python
Magic Methods are the special methods which gives us the ability to access built in syntactical features such as ‘<’, ‘>’, ‘==’, ‘+’ etc…
You must have worked with such methods without knowing them to be as magic methods. Magic methods can be identified with their names which start with __ and ends with __ like init, call, str etc. These methods are also called Dunder Methods, because of their name starting and ending with Double Underscore (Dunder).
Now there are a number of such special methods, which you might have come across too, in Python. We will just be taking an example of a few of them to understand how they work and how we can use them.
1. init
class AnyClass:
def __init__():
print("Init called on its own")
obj = AnyClass()
The first example is _init, _and as the name suggests, it is used for initializing objects. Init method is called on its own, ie. whenever an object is created for the class, the init method is called on its own.
The output of the above code will be given below. Note how we did not call the init method and it got invoked as we created an object for class AnyClass.
Init called on its own
2. add
Let’s move to some other example, add gives us the ability to access the built in syntax feature of the character +. Let’s see how,
class AnyClass:
def __init__(self, var):
self.some_var = var
def __add__(self, other_obj):
print("Calling the add method")
return self.some_var + other_obj.some_var
obj1 = AnyClass(5)
obj2 = AnyClass(6)
obj1 + obj2
#python3 #python #python-programming #python-web-development #python-tutorials #python-top-story #python-tips #learn-python
1623287770
How To Create an Instagram Profile Analyzer App Using Python and Streamlit
Streamlit is a great library that helps us create python apps with minimum effort. Not only it’s easy but its UI is beautiful and seems very professional. Our Idea for this post is to create an Instagram Dashboard having some descriptive statistics about a user’s profile like most frequent hashtags, top liked posts, engagement rate, etc. Having said that, we need an application that takes as input a user name and will scrape its information from Instagram to return the final Dashboard.
Getting the data from Instagram
Building our Streamlit APP
…
#python #instagram #python #python app #streamlit #create an instagram profile analyzer app using python