The installation-dependent default by convention including a site-packages directory, handled by the site module. On file systems which support symlinks, the directory containing the input script is calculated after the symlink is followed.
In other words the directory containing the symlink is not added to the module search path. After initialization, Python programs can modify sys. The directory containing the script being run is placed at the beginning of the search path, ahead of the standard library path.
This means that scripts in that directory will be loaded instead of modules of the same name in the library directory. This is an error unless the replacement is intended. See section Standard Modules for more information. For example, in CPython release 3. This naming convention allows compiled modules from different releases and different versions of Python to coexist. This is a completely automatic process. Also, the compiled modules are platform-independent, so the same library can be shared among systems with different architectures.
Python does not check the cache in two circumstances. Second, it does not check the cache if there is no source module. To support a non-source compiled only distribution, the compiled module must be in the source directory, and there must not be a source module. You can use the -O or -OO switches on the Python command to reduce the size of a compiled module.
Future releases may change the effects of optimization. The module compileall can create. There is more detail on this process, including a flow chart of the decisions, in PEP Some modules are built into the interpreter; these provide access to operations that are not part of the core of the language but are nevertheless built in, either for efficiency or to provide access to operating system primitives such as system calls.
The set of such modules is a configuration option which also depends on the underlying platform. For example, the winreg module is only provided on Windows systems. One particular module deserves some attention: sys , which is built into every Python interpreter. The variables sys. The variable sys. You can modify it using standard list operations:. The built-in function dir is used to find out which names a module defines.
It returns a sorted list of strings:. Python Design Patterns. Python Pillow. Python Turtle. Verbal Ability. Interview Questions. Company Questions. Artificial Intelligence. Cloud Computing. Data Science. Angular 7. Machine Learning. Data Structures. Operating System. Computer Network. Compiler Design. Computer Organization. Discrete Mathematics. Ethical Hacking. Computer Graphics. Software Engineering. Web Technology. This tutorial covered how to write definitions within a module, make use of those definitions within another Python programming file, and went over options of where to keep the module in order to access it.
You can learn more about installing and importing modules by reading How To Import Modules in Python 3. Python is a flexible and versatile programming language that can be leveraged for many use cases, with strengths in scripting, automation, data analysis, machine learning, and back-end development.
It is a great tool for both new learners and experienced developers alike. Where would you like to share this to? Twitter Reddit Hacker News Facebook. Share link Tutorial share link. Sign Up. DigitalOcean home. Community Control Panel. Hacktoberfest Contribute to Open Source. How To Code in Python. How To Write Modules in Python 3. How To Write Comments in Python 3. Understanding Data Types in Python 3.
An Introduction to Working with Strings in Python 3. An Introduction to String Functions in Python 3. Python's from statement lets you import specific attributes from a module into the current namespace. The from This statement does not import the entire module fib into the current namespace; it just introduces the item fibonacci from the module fib into the global symbol table of the importing module. This provides an easy way to import all the items from a module into the current namespace; however, this statement should be used sparingly.
If all else fails, Python checks the default path. The module search path is stored in the system module sys as the sys. The sys. Variables are names identifiers that map to objects. A namespace is a dictionary of variable names keys and their corresponding objects values. A Python statement can access variables in a local namespace and in the global namespace. If a local and a global variable have the same name, the local variable shadows the global variable.
Each function has its own local namespace. Class methods follow the same scoping rule as ordinary functions. Python makes educated guesses on whether variables are local or global.
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