What is python Introspection ?
Introspection used to self examination of python objects Properties and type at the runtime. By using introspection, we can dynamically inspect Python objects.
List of important Introspection
dir()
type
id()
sys
hasattr()
issubclass()
callable()
dir()
It returns a sorted list of attributes and methods belonging to an object.
syntax:
>>> dir(())
Output:
['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__',
'__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__',
'__getslice__', '__gt__', '__hash__', '__init__', '__iter__', '__le__',
'__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__',
'__reduce_ex__', '__repr__', '__rmul__', '__setattr__', '__sizeof__',
'__str__', '__subclasshook__', 'count', 'index']
Here we use dir() with different ways:
obj = classname()
print(dir(obj))
print(dir([]))
print(dir({}))
print(dir(1))
print(dir())
print(dir(len))
print(dir(sys))
print(dir("String"))
Add modules in dir()
In dir() add modules using import
>>> import math, os
>>> dir()
It import two module, math and os in dir()
type()
It returns the type of an object.
Example:
#!/usr/bin/python3
# typefun.py
import sys
def function():
pass
class MyClass(object):
def __init__(self):
pass
o = MyClass()
print(type(1))
print(type(""))
print(type([]))
print(type({}))
Output:
<class 'int'>
<class 'str'>
<class 'list'>
<class 'dict'>
id() function
It returns a special id of an object.
Example:
#!/usr/bin/python3
# idfun.py
import sys
def function():
pass
class MyClass(object):
def __init__(self):
pass
o = MyClass()
print(id(1))
print(id(""))
print(id({}))
print(id([]))
Output:
10914368
139696088742576
139696087935944
139696065155784
sys module
It provides access to system specific variables and functions used or maintained by the interpreter and to functions that interact strongly with the interpreter.
First import the sys module:
>>> import sys
If you want to check which platform is running currently then use this
>>> sys.platform
It return the system python where python script folder exists:
>>> sys.path
hasattr() function
It checks if an object has an attribute
callable() function
It checks if an object is a callable object (a function).
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