Python Introspection

Internal

• Python Object-Oriented Programming

TODO

https://www.geeksforgeeks.org/code-introspection-in-python/

Overview

Introspection is Python's equivalent for Java reflection. It is the ability to determine the type of an object at runtime and to dynamically examine Python objects.

getattr()

getattr() is a built-in function that returns the value of the specified attribute from the specified object. If an attribute with such name does not exist, an AttributeError exception is thrown.

cls = ...
method_name = 'some_static_method'
try:
  method = getattr(cls, method_name)
  print(method)
except AttributeError:
  print(f"{method_name} method not found in class {cls}")

The inspect Standard Library Module

https://docs.python.org/3/library/inspect.html#module-inspect

inspect is a Standard Library module.

getmembers()

getmembers() returns all members of an object as (name, value) pairs sorted by name. The object can be a module, class, etc. A predicate can be provided to the function, and the function returns only return members that satisfy a given predicate.

Example of how classes in a module can be identified:

import inspect

modules = sys.modules.copy()
module = modules['some_package.some_subpackage.SomeClass']
class_tuples = inspect.getmembers(module, inspect.isclass)
for ct in class_tuples:
  print('class name: ', ct[0])
  print('class: ', ct[1])

Module Introspection

Also see:

Python Language Modularization

Find classes in a module:

import inspect

module = sys.modules['some_package.some_subpackage.SomeClass']
class_tuples = inspect.getmembers(module, inspect.isclass)
for ct in class_tuples:
  print('class name: ', ct[0])
  print('class: ', ct[1])

Class Instance Introspection

Find Static Methods in a Class

A specific static method can be identified by querying the class attributes with inspect.getmembers() and selecting the matching method, or by name with getattr() builtin.

Find classes in a module:

import inspect

cls = ...qualification_method = getattr(ct[1], 'some_static_method')