`inspect`

The Python inspect module provides several useful tools to help you get information about live objects, such as modules, classes, methods, functions, tracebacks, and the objects’ source code.

It allows you to inspect the types and properties of these objects, retrieve source code, and get information on the calling context.

Here’s an example:

Python
      
>>> import inspect

>>> def example_function():
...     pass
...

>>> inspect.isfunction(example_function)
True

Key Features

Retrieves the source code of objects
Inspects classes, functions, and methods
Examines the stack frame
Analyzes the arguments of callable objects
Retrieves information about the calling context

Frequently Used Classes and Functions

Object	Type	Description
`inspect.getsource()`	Function	Returns the text of the source code for an object
`inspect.getmembers()`	Function	Returns all members of an object as name-value pairs
`inspect.isfunction()`	Function	Checks if an object is a function
`inspect.signature()`	Function	Gets a callable’s signature
`inspect.getdoc()`	Function	Retrieves the docstring of an object
`inspect.isclass()`	Function	Returns `True` if the object is a class, whether built-in or created in Python code
`inspect.currentframe()`	Function	Returns the current stack frame

Examples

Retrieving the source code of a function:

Python
      
        
      
    
>>> import inspect

>>> def example_function():
...     """This is an example function."""
...     pass

>>> print(inspect.getsource(example_function))
def example_function():
    """This is an example function."""
    pass

Checking if an object is a class:

Python
      
>>> class ExampleClass:
...     pass
...

>>> inspect.isclass(ExampleClass)
True

Getting the signature of a function:

Python
      
>>> def example_function(a, b=2, *args, **kwargs):
...     pass
...

>>> inspect.signature(example_function)
<Signature (a, b=2, *args, **kwargs)>

Common Use Cases

Retrieving and displaying the source code of functions and classes
Analyzing function signatures and arguments
Debugging and understanding the stack trace
Generating documentation or interactive help

Real-World Example

Suppose you want to create a simple command-line tool that inspects functions within a module and displays their signatures and docstrings. Here’s a way to achieve that:

Python
      
        
      
    
>>> import inspect
>>> import custom_module

>>> for name, obj in inspect.getmembers(custom_module, inspect.isfunction):
...     print(f"Function: {name}")
...     print(f"Signature: {inspect.signature(obj)}")
...     print(f"Docstring: {inspect.getdoc(obj)}\n")
...

This example demonstrates how to list all functions in a custom module, showing their signatures and docstrings, which can be particularly useful for documentation purposes or understanding a codebase.

Tutorial

Serialize Your Data With Python

In this in-depth tutorial, you'll explore the world of data serialization in Python. You'll compare and use different data serialization formats, serialize Python objects and executable code, and handle HTTP message payloads.

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For additional information on related topics, take a look at the following resources: