Python import statement 






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Introduction The Python programming language comes with a variety of. We use modules to break down large programs into small manageable and organized files.
It would be impossible to assign to a global variable without , although free variables may refer to globals without being declared global. It assumes that any variable assigned a value in a function is local. The argument to the import function can be a single name, or a list of multiple names. An import statement is made up of the import keyword along with the name of the module.
Python also provides extensive collection manipulating abilities such as built in containment checking and a generic iteration protocol. My suggestion is to make a list of your favorite modules and functions and learn how they work; if you need a new one, check out the original Python documentation and add the new module plus its function to your list. It should yield a mutable sequence object such as a list. Numbers, strings, sequences, and mappings can all be compared. We use modules to break down large programs into small manageable and organized files. As I have mentioned, there is a Python Standard Library with dozens of built-in modules. One function is called when entering scope and another when leaving.
Importing Python Modules - Simply, a module is a file consisting of Python code. This note tries to sort out some of the more common issues related to import and from-import and everything.
January 07, 1999 Updated February 02, 2001 Fredrik Lundh Introduction The import and from-import statements are a constant cause of serious confusion for newcomers to Python. This note tries to sort out some of the more common issues related to import and from-import and everything. There are Many Ways to Import a Module Python import statement provides at least three different ways to import modules. But X itself is not defined, so X. And if name was already defined, it is replaced by the new python import statement. Or in other words, you can now use a and b and c in your program. Which Way Should I Use. Short answer: always use import. The most common example in this category is Tkinter, which is carefully designed to add only the widget classes and related constants to your current namespace. Using import Tkinter only makes your program harder to read; something that is generally a bad idea. Also see the next item. If you think you do, just go ahead and use from-import. But think twice before you ask for help ;- What Does Python Do to Import a Module. When Python imports a module, it first checks the module registry sys. All variables assigned by the code will be available via the module object. Import Gotchas Using Modules as Scripts If you run a module as a script i. Circular Imports In Python, things like def, class, and import are statements too. When Python reaches the import Y statement, it loads the code for Y, and starts executing it instead. At this time, Python has installed module objects for both X and Y in sys. Any attempt to access the X. To fix this, either refactor your program to avoid circular imports moving stuff to a separate module often helpsor move the imports to python import statement end of the module in this case, if you move import Y to the end of module X, everything will work just fine. Copyright © 1998-2001 by Fredrik Lundh.