Question

I have a situation where I am attempting to port some big, complex python routines to a threaded environment.

I want to be able to, on a per-call basis, redirect the output from the function’s print statement somewhere else (a logging.Logger to be specific).

I really don’t want to modify the source for the code I am compiling, because I need to maintain backwards compatibility with other software that calls these modules (which is single threaded, and captures output by simply grabbing everything written to sys.stdout).

I know the best option is to do some rewriting, but I really don’t have a choice here.

Edit –

Alternatively, is there any way I can override the local definition of print to point to a different function?

I could then define the local print = system print unless overwritten by a kwarg, and would only involve modify a few lines at the beginning of each routine.

Answer 1

In Python2.6 (and 2.7), you can use

from __future__ import print_function

Then you can change the code to use the print() function as you would for Python3

This allows you to create a module global or local function called print which will be used in preference to the builtin function

eg.

from __future__ import print_function

def f(x, print=print):
    print(x*x)

f(5)
L=[]
f(6, print=L.append)
print(L)