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In Python, global variables are module-specific, meaning they exist within the scope of a single module rather than being shared across all modules like in C. Understanding this concept is crucial for managing data across multiple Python files. Global Variables Are Module-Specific When you define a global variable in a Python module, it's only accessible within that module. Each module maintains its own global namespace ? # module1.py (simulated) counter = 0 def increment(): global counter counter += 1 return counter print("Module1 ... Read More
Namespace packages are a type of package in Python that allows you to split sub-packages and modules within a single package across multiple, separate distribution packages. Unlike normal packages, namespace packages don't require an __init__.py file. Automatically importing all submodules within a namespace package serves several purposes, like auto-registration without manually importing, and loading all available plugins in a system. Using pkgutil.iter_modules() The pkgutil.iter_modules() function finds and lists submodules and subpackages within a given package. It returns an iterator containing ModuleInfo objects, each with information about a found module or package ? import pkgutil import ... Read More
Namespace packages are a special type of package introduced in Python 3.3 that allows you to split package contents across multiple directories. If you don't include at least an empty __init__.py file in your package, then your package becomes a namespace package. In Python, a namespace package allows you to spread Python code among several projects. This is useful when you want to release related libraries as separate downloads. Currently, there are three methods for developing namespace packages: Native namespace packages (PEP 420) pkgutil-style namespace packages ... Read More
Yes, recursive functions in Python create a new namespace each time the function calls itself. This is true for any function call, not just recursive ones. However, when objects are passed as parameters, they are passed by reference. The new namespace gets its own copy of this reference, but it still refers to the same object as in the calling function. If you modify the content of that object, the change will be visible in the calling function. How Python Handles Function Calls When the Python interpreter encounters a function call, it creates a frame object that ... Read More
This article explains what the Python expression if __name__ == '__main__' means and how it's used to control code execution. A Python program uses the condition if __name__ == '__main__' to run specific code only when the program is executed directly by the Python interpreter. The code inside the if statement is not executed when the file is imported as a module. Understanding the __name__ Variable The variable __name__ is a special built−in variable in Python. Python has many special variables that begin and end with double underscores, called "dunder" variables (from Double Underscores). In this case, ... Read More
In Python, a namespace package allows you to spread Python code among several projects. This is useful when you want to release related libraries as separate downloads while maintaining a unified import structure. Directory Structure Example With the directories Package-1 and Package-2 in PYTHONPATH, you can organize your code as follows − Package-1/ namespace/ __init__.py module1/ __init__.py Package-2/ namespace/ ... Read More
Python allows you to install and import modules at runtime using subprocess to call pip and importlib to dynamically import modules. This is useful for optional dependencies or when you want to handle missing packages gracefully. Modern Approach Using subprocess The recommended way to install packages programmatically is using subprocess instead of calling pip directly ? import subprocess import importlib import sys def install_and_import(package): try: return importlib.import_module(package) except ImportError: print(f"Installing {package}...") ... Read More
Easy Install was a Python package management tool bundled with setuptools that allowed automatic downloading, compiling, installing, and managing of Python packages. Introduced in 2004, it was groundbreaking for automatically handling dependencies and installing packages from PyPI. However, easy_install is now deprecated and has been replaced by pip as the standard Python package installer. Installing pip using easy_install If you have an older system with only easy_install available, you can use it to install pip ? easy_install pip Basic easy_install Usage To install a package, you simply specify the package name after the ... Read More
Azure Functions for Python provides several methods to import and use external modules. While early versions had limitations, modern Azure Functions offers better support for dependency management. Method 1: Using requirements.txt (Recommended) The most straightforward approach is to create a requirements.txt file in your function app root directory − # requirements.txt requests==2.28.2 pandas==1.5.3 numpy==1.24.3 Azure Functions will automatically install these dependencies during deployment. Then import them normally in your function code − import azure.functions as func import requests import pandas as pd def main(req: func.HttpRequest) -> func.HttpResponse: ... Read More
There are several ways to check if a Python module exists without importing it. This is useful when you want to conditionally use a module or handle missing dependencies gracefully. Using importlib.util.find_spec() (Recommended) The modern approach uses importlib.util.find_spec() which is available in Python 3.4+ − import importlib.util def module_exists(module_name): spec = importlib.util.find_spec(module_name) return spec is not None print(module_exists('os')) # Built-in module print(module_exists('nonexistent_module')) True False Using pkgutil.iter_modules() You can iterate over all available modules to check if a specific module ... Read More