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Programming Articles
Page 2519 of 2547
Python bootstrapping the pip installer
In addition to the modules and packages built in to the standard distribution of Python, large number of packages from third party developers are uploaded to Python package repository called Python Package Index (https://pypi.org/. To install packages from here, pip utility is needed. The pip tool is an independent project, but since Python 3.4, it has been bootstrapped in Python distribution.The ensurepip module provides support for bootstrapping pip in existing installation of Python. Normally user doesn't need to use it explicitly. If however, installation of pip is skipped in normal installation or virtual environment, it may be needed.Following command will ...
Read MorePython Low-level threading API
The '_thread' module in Python library provides a low-level interface for working with light-weight processes having multiple threads sharing a global data space. For synchronization, simple locks (also called mutexes or binary semaphores) are defined in this module. The 'threading' built-in module provides a higher-level threading API built on top of this module.start_new_thread()This module-level function is used to open a new thread in the current process. The function takes a function object as an argument. This function gets invoked on successful creation of the new thread. The span of this function corresponds to the lifespan of the thread. The thread ...
Read MoreTrace or track Python statement execution (trace)
Function in the 'trace' module in Python library generates trace of program execution, and annotated statement coverage. It also has functions to list functions called during run by generating caller relationships.Following two Python scripts are used as an example to demonstrate features of trace module.#myfunctions.py import math def area(x): a = math.pi*math.pow(x, 2) return a def factorial(x): if x==1: return 1 else: return x*factorial(x-1)#mymain.py import myfunctions def main(): x = 5 print ('area=', myfunctions.area(x)) ...
Read MoreByte-compile Python libraries
Python is an interpreter based language. However it internally compiles the source code to byte code when a script (.py extension) is run and afterwards the bytecode version is automatically removed. When a module (apart from the precompiled built-in modules) is first imported, its compiled version is also automatically built but saved with .pyc extension in __pycache__ folder. Subsequent calls to import same module again won't recompile the module instead uses the one already built.However, a Python script file with .py extension can be compiled expilicitly without running it. The 'py_compile' module contains 'compile()' function for that purpose. Name of ...
Read MorePython class browser support
The pyclbr module in Python library extracts information about the functions, classes, and methods defined in a Python module. The information is extracted from the Python source code rather than by importing the module.This module defines readmodule() function that return a dictionary mapping module-level class names to class descriptors. The function takes a module name as parameter. It may be the name of a module within a package. In that case path is a sequence of directory paths prepended to sys.path, which is used to locate the module source code.Following code uses readmodule() function to parse classes and methods in ...
Read MorePython import modules from Zip archives (zipimport)
Use of 'zipimport' module makes it possible to import Python modules and packages from ZIP-format archives. This module also allows an item of sys.path to be a string naming a ZIP file archive. Any files may be present in the ZIP archive, but only files .py and .pyc are available for import. ZIP import of dynamic modules is disallowed.Functionality of this module is explained by first building a zip archive of files in 'newdir' directory. Following files are assumed to be present in newdir directory['guess.py', 'hello.py', 'impzip.py', 'mytest.py', 'prime.py', 'prog.py', 'tmp.py']import sys, glob import zipfile files = glob.glob("*.py") print (files) ...
Read MoreBasics of Discrete Event Simulation using SimPy in Python
SimPy (rhymes with “Blimpie”) is a python package for process-oriented discrete-event simulation.InstallationThe easiest way to install SimPy is via pip:pip install simpyAnd the output you may get will be something like, At the time of writing, simpy-3.0.11 is the most recent version of SimPy, and we will use it for all the below examples.In case, SimPy is already installed, use the –U option for pip to upgrade.pip install –U simpyNote: You need to have python 2.7 or above version and for Linux/Unix/MacOS you may need root privileges to install SimPy.To check if SimPy was successfully installed, open a python shell ...
Read MorePython Binary Data Services
Provisions of the struct module in the Python library are useful in performing conversions between C type structs and Python bytes objects. This can be achieved by module level functions as well as Struct class and its methods as defined in the struct module.The conversion functions use a format string. The byte order, size, and alignment used in the format string is determined by formatting character as per the following tableCharacterByte orderSizeAlignment@nativenativenative=nativestandardnonebig-endianstandardnone!network (= big-endian)standardnoneFollowing table shows format characters used to denote C type variables and corresponding Python types.FormatC TypePython typexpad byteno valueccharbytes of length 1b/Bsigned/unsigned charinteger?_Boolboolh/Hshort/unsigned shortintegeri/Iint/unsigned intintegerl/Llong/unsigned longintegerffloatfloatddoublefloatschar[]bytespchar[]bytesPvoid *integerFollowing ...
Read MorePython Vs Ruby, which one to choose?
First thing comes in my mind, why to compare these two language only? This may be because both are interpreted, agile languages with an object oriented philosophy and very huge communities support. However, though both languages share some ideas, syntax elements and have almost the same features the two communities have nothing in common.Both the languages are very popular among the developer’s community (This is also one of the reasons to compare). Below are the top ten most popular languages in 2018 on GitHub based on opened pull request −Top 10 most popular languages on GitHub based on opened pull ...
Read MoreSimple registration form using Python Tkinter
Tkinter is a python library for developing GUI (Graphical User Interfaces). We use the tkinter library for creating an application of UI (User Interface), to create windows and all other graphical user interfaces.If you’re using python 3.x(which is recommended), Tkinter will come with Python as a standard package, so we don’t need to install anything to use it.Before creating a registration form in Tkinter, let’s first create a simple GUI application in Tkinter.Creating a simple GUI applicationBelow is the program to create a window by just importing Tkinter and set its title −from tkinter import * from tkinter import ttk ...
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