How to retrieve source code from Python objects?

We are given a object and our task is to retrieve its source code, for this we have inspect module, dill module and dis module built-in standard libraries in Python programming. They provide several useful functions to track information about live objects such as modules, classes, methods, functions, tracebacks, frame objects, and code objects. getsource() method is used to get the source code of Python objects.

Syntax: inspect.getsource(object)

Parameter: The object type parameter, of which we want the source code.

Return type: text of the source code for an object

Note: An IOError is raised if the source code cannot be retrieved.

Using the inspect module to retrieve source code

Example: Here we are importing the inspect module first and then using the inspect.getsource() function to fetch the source code of the given object.

python3

# import inspect library
import inspect

def test(x):
    return x * 2

print(inspect.getsource(test))

Output:

def test(x):

   return (x+2)*(x-2)

Example: Here we are fetching the source code for the given object.

python3

# import inspect library
import inspect


def far(n):
    factorial = 1
    if int(n) >= 1:
        for i in range (1, int(n)+1):
            factorial = factorial * i
    return factorial

source = inspect.getsource(far)
print(source)

Output:

def far(n):
    factorial = 1
    if int(n) >= 1:
        for i in range (1, int(n)+1):
            factorial = factorial * i
    return factorial

Example: We can use inspect on built in library functions and objects also. 

python3

# import inspect library
import inspect
import pandas


source_DF = inspect.getsource(pandas.DataFrame)
print(source_DF[:100])

Output:

class DataFrame(NDFrame):
    """
    Two-dimensional size-mutable, potentially heterogeneous tabula

Using the dis module to retrieve source code

Here we are using the dis module in Python to fetch the source code of the specified object.

Python3

import dis

def fun(a1, a2):
    # do something with args
    a = a1 + a2
    return a


dis.dis(fun)

Output:

 50           0 LOAD_FAST                0 (a1)
              2 LOAD_FAST                1 (a2)
              4 BINARY_ADD
              6 STORE_FAST               2 (a)

 51           8 LOAD_FAST                2 (a)
             10 RETURN_VALUE

Using the dill module to retrieve source code

Here we are using the dill module in Python to fetch the source code of the specified object.

Python3

import dill

def fun(a1,a2):
    a = a1 + a2
    return a

source=dill.source.getsource(fun)
print(source[:200])

Output:

def fun(a1,a2):
    a = a1 + a2
    return a