Python functions that can modify their own input

Question

I want to create a Python function that can inspect its own input, rather than the output of its input. For example, a function raw_str that returns its input exactly, as a string:

>>> raw_str(2+2)
'2+2'

rather than:

>>> str(2+2)
'4'

Is there any way to do this?

Is raw_str('2+2') acceptable? Otherwise, @JBernardo is right. — Brian Cain
– Brian Cain, Commented Oct 28, 2012 at 2:49
In Ruby this is sometimes done by the library implementing such a function parsing the source of the call-site and providing the function output based on such a scan. I'm not sure how well such an approach would work in Python. — Jakub Hampl
– Jakub Hampl, Commented Oct 28, 2012 at 2:52

arshajii · Accepted Answer · 2014-01-24 16:17:25Z

9

This is not possible because the arguments are evaluated before they are passed on to the function - so there will be no way to distinguish between 2 + 2 and 3 + 1 (for instance) within the function body. Without more context, it's hard to suggest possible solutions to the problem.

edited Jan 24, 2014 at 16:17

answered Oct 28, 2012 at 2:49

arshajii

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