Python – How to get the source code of a Python function

functionpython

Suppose I have a Python function as defined below:

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

I can get the name of the function using foo.func_name. How can I programmatically get its source code, as I typed above?

Best Answer

If the function is from a source file available on the filesystem, then inspect.getsource(foo) might be of help:

If foo is defined as:

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

Then:

import inspect
lines = inspect.getsource(foo)
print(lines)

Returns:

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

But I believe that if the function is compiled from a string, stream or imported from a compiled file, then you cannot retrieve its source code.

Related Solutions

Python – Calling a function of a module by using its name (a string)

Assuming module foo with method bar:

import foo
method_to_call = getattr(foo, 'bar')
result = method_to_call()

You could shorten lines 2 and 3 to:

result = getattr(foo, 'bar')()

if that makes more sense for your use case.

You can use getattr in this fashion on class instance bound methods, module-level methods, class methods... the list goes on.

Python – How to execute a program or call a system command

Use the subprocess module in the standard library:

import subprocess
subprocess.run(["ls", "-l"])

The advantage of subprocess.run over os.system is that it is more flexible (you can get the stdout, stderr, the "real" status code, better error handling, etc...).

Even the documentation for os.system recommends using subprocess instead:

The subprocess module provides more powerful facilities for spawning new processes and retrieving their results; using that module is preferable to using this function. See the Replacing Older Functions with the subprocess Module section in the subprocess documentation for some helpful recipes.

On Python 3.4 and earlier, use subprocess.call instead of .run:

subprocess.call(["ls", "-l"])

Best Answer

Related Solutions

Python – Calling a function of a module by using its name (a string)

Python – How to execute a program or call a system command

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