One way to do this is:
- Duplicate in python the file descriptors for
stdout and stderr using os.dup.
- Redirect the original
stdout and stderr using reopen (from C's stdio) to write to a file of your choice.
Note: reopen isn't available directly from python, but you should be able to call it as in the example below or using any other wrapper available.
After this is done:
- Every write to
cout and cerr in C++ will write to the output files.
- Every
print statement in python will write to the output files.
However, since the original descriptors are duplicated, you can still (see example below):
- Print to the original
stdout/stderr using sdout.write and stdout.err
- Use
logging methods after configuring properly the stream parameter
The following code uses instant library to test real C++ code that is wrapped into python using SWIG and that should be similar to the library that you have:
import sys, os
import logging
from instant import inline
print 'This is printed from python to stdout'
stdout = os.fdopen(os.dup(sys.stdout.fileno()), 'w')
stderr = os.fdopen(os.dup(sys.stderr.fileno()), 'w')
logging.basicConfig(stream=stderr, level=logging.DEBUG)
redirect = inline("""
void redirect(void) {
freopen("my_stdout.txt", "w", stdout);
freopen("my_stderr.txt", "w", stderr);
}
""")
redirect()
cout = inline("""
void cout(void) {
std::cout << "This is written from C++ to my_stdout.txt" << std::endl;
std::cerr << "This is written from C++ to my_stderr.txt" << std::endl;
}
""")
cout()
print 'This is written from python to my_stdout.txt'
stdout.write('This is printed from python to stdout\n')
stderr.write('This is printed from python to stderr\n')
logging.info('This is printed to stderr from python using logging')
The output for this example is:
$ python test.py
This is printed from python to stdout
This is printed from python to stdout
This is printed from python to stderr
INFO:root:This is printed to stderr from python using logging
$ cat my_stdout.txt
This is written from C++ to my_stdout.txt
This is written from python to my_stdout.txt
$ cat my_stderr.txt
This is written from C++ to my_stderr.txt
Note: First time the code is executed, you might get gcc compilation messages (I've removed them to make the example clearer).
