Can a python script be used to generate and write a C++ file/program?

Question

I am doing unit testing as part of my intern-ship. My boss is always telling me that finding a way to automate things is the best way and I was wondering if it would be possible to use python, to write a script that would read a text file with a certain structure and syntax and then generate a c++ file based off of said text file?

I am using Google-Test to do unit testing and I just think it would be a good addition to the companies tools but I would just like to know if its possible and if anyone else has done something similar.

Thanks!

Answer 1

Yes, this is certainly doable. I've done this before (we use Python internally to create some C++ code to read and write structures). You can just use custom scripts (like @Kevin says in his comment, it's easy), or you can use a Python tool like Cog if you want a more structured approach.

As with anything, there are tradeoffs. Using Python to generate C++ code means that the developers have another language to learn (not a big deal, Python's worth learning and complements C++ well), and there's an extra level of indirection in your development and build process, and there's extra (Python) code to maintain. If you go this route, remember that simplicity is a virtue; don't get sucked into trying to write a singing, dancing "generate every kind of C++ code imaginable" framework.

Answer 2

The answer from Josh is good if you want to scale up, but I thought you'd like to see what it looks like in action for a simple example. Most of the work is done with the subprocess module. Here I'm using a Linux machine so my compiler is gcc, but it is relatively easy to see how you can make this dependent on your specific system architecture.

import subprocess

code = r'''
#include <stdio.h>
int main() {
  for(int i=0;i<5;i++) {
    printf("Testing %d\n",i);
  }
  return 0;
}
'''

f_cpp = "test.cpp"
with open(f_cpp,'w') as FOUT:
    FOUT.write(code)

# Compile the program
f_exec = "./myprogram"
compile_cmd = "gcc {} -o {}".format(f_cpp, f_exec)
subprocess.call(compile_cmd, shell=True)

# Run the program
p = subprocess.Popen(f_exec, shell=True,
                     stdin=subprocess.PIPE, 
                     stdout=subprocess.PIPE)

# Step through the output 
for line in p.stdout:
    print line

This gives as output:

Testing 0   
Testing 1
Testing 2
Testing 3
Testing 4