u11-script-modules-packages Flashcards
What is the difference between import sys and from sys import path?
import sys imports the entire module and requires using sys. prefix to access contents, while from sys import path imports only the path object directly into the current namespace.
How do you import a module with an alias?
Use the as keyword: import sys as system. This allows you to reference the module using the alias name instead of the original name.
What does dir(module_name) do?
The dir() function shows all names (attributes and methods) defined in the specified module. Example: dir(sys) shows all contents of the sys module.
How can you import multiple items from a module in a single line?
Use commas to separate the items: from os import path, makedirs. You can also import multiple modules: import os, sys.
What happens if you import a module multiple times in Python?
Python will only perform the import once by default, regardless of how many times the import statement appears.
Why is using from module import * generally discouraged?
It can overwrite existing names in your namespace and makes it unclear where names come from, making code harder to maintain and understand.
What is the PYTHONPATH environment variable used for?
PYTHONPATH specifies additional directories where Python should look for modules to import. Python searches these directories along with the working directory.
How do you set PYTHONPATH in Linux?
Use the command: export PYTHONPATH=/path/to/your/module:$PYTHONPATH. To make it permanent, add this line to your ~/.bashrc file.
What is the purpose of the if \_\_name\_\_ == "\_\_main\_\_": block?
It allows code to be executed only when the file is run directly as a script, not when it’s imported as a module. This helps separate importable code from executable code.
What makes a directory a Python package?
Adding an empty \_\_init\_\_.py file to a directory makes Python treat it as a package, allowing you to import modules from that directory.
How do you import a function from a nested package?
Use dot notation to specify the path: from package.subpackage.module import function. Example: from sound.effects.echo import echofilter
What’s the difference between a module and a package in Python?
A module is a single Python file containing code, while a package is a directory containing multiple modules and an \_\_init\_\_.py file.
How do you import a specific function and rename it?
Use the as keyword with from import: from module import function as new_name. Example: from my_module import add as my_add
What happens when you import from a file?
The content of the file is executed when it’s imported, unless the code is inside an if \_\_name\_\_ == "\_\_main\_\_": block.
How do you import a module from a subdirectory?
Use dot notation: from directory.module import item. Example: from sound.formats.wavread import readwav
What is the purpose of \_\_init\_\_.py file?
It marks a directory as a Python package, making it possible to import modules from that directory. The file can be empty or contain initialization code.
How can you check what names are defined in your current namespace?
Use the dir() function without arguments to see all names in the current namespace.
What’s the difference between absolute and relative imports?
Absolute imports use the full path from the root package (e.g., from sound.effects import echo), while relative imports use dots to reference relative to current package (e.g., from ..effects import echo).
How do you import all submodules from a package?
You typically don’t - you should import specific modules or functions. However, a package’s \_\_init\_\_.py can define \_\_all\_\_ to specify what is imported with from package import *.
What happens if you try to import a module that doesn’t exist?
Python raises an ImportError (or ModuleNotFoundError, which is a subclass of ImportError) if it cannot find the specified module.
