How can I get the source code of a Python function?

Question

Suppose I have a Python function as defined below:

def foo(arg1,arg2):
    #do something with args
    a = arg1 + arg2
    return a

I can g

Answer 1

If you're strictly defining the function yourself and it's a relatively short definition, a solution without dependencies would be to define the function in a string and assign the eval() of the expression to your function.

E.g.

funcstring = 'lambda x: x> 5'
func = eval(funcstring)

then optionally to attach the original code to the function:

func.source = funcstring

Answer 2

The inspect module has methods for retrieving source code from python objects. Seemingly it only works if the source is located in a file though. If you had that I guess you wouldn't need to get the source from the object.

Answer 3

to summarize :

import inspect
print( "".join(inspect.getsourcelines(foo)[0]))

Answer 4

dis is your friend if the source code is not available:

>>> import dis
>>> def foo(arg1,arg2):
...     #do something with args
...     a = arg1 + arg2
...     return a
...
>>> dis.dis(foo)
  3           0 LOAD_FAST                0 (arg1)
              3 LOAD_FAST                1 (arg2)
              6 BINARY_ADD
              7 STORE_FAST               2 (a)

  4          10 LOAD_FAST                2 (a)
             13 RETURN_VALUE

Answer 5

If you are using IPython, then you need to type "foo??"

In [19]: foo??
Signature: foo(arg1, arg2)
Source:
def foo(arg1,arg2):
    #do something with args
    a = arg1 + arg2
    return a

File:      ~/Desktop/<ipython-input-18-3174e3126506>
Type:      function

Answer 6

I believe that variable names aren't stored in pyc/pyd/pyo files, so you can not retrieve the exact code lines if you don't have source files.