How can I catch reports from Operators in Python script?

Question

Is it possible to catch reports from Operators in a Python script?

For example, the Operator bpy.ops.object.modifier_apply() shows errors in the console when something goes wrong. I'd be happy to have a try... catch... method to handle those.

Same with some addons like 3D Print Toolbox who send back useful info in the console and UI, but I can't seem to find a way to catch those. Is this possible?

Update:
To give a concrete example, this file uses a boolean modifier on two objects and when applied, the Operator returns a lot of WARNING or errors in the console. How could I catch those?

Answer 1

For Operator Error Reports

Catching Errors is handled separately, this example catches the error report and prints it as a string.

import bpy
try:
    bpy.ops.object.vertex_group_add()
except RuntimeError as ex:
    error_report = "\n".join(ex.args)
    print("Caught error:", error_report)

For Operator Info Reports

Python can temporarily redirect the stdout using contextlib, this is ideal since you may not want to suppress output for _all_ scripts, just selectively redirect some output.

eg:

import bpy

import io
from contextlib import redirect_stdout

stdout = io.StringIO()
with redirect_stdout(stdout):
    bpy.ops.mesh.remove_doubles()

If you want you can read the output back out or use it however you like.

stdout.seek(0)
output = stdout.read()
print("Report was %r" % output)

Answer 2

This is a hack I found to solve parts of this problem. It will work with Operators using the report() function to display data back to the user but don't provide a way to catch that data in other ways.

Those reports are both displayed in the Information window and in the console. So the trick I found is to do temporarily reroute the stdout from Python to a text file and re-read the text file afterwards.

# Opens a text file to write the reports
def openLogs():
    logfile = open( bpy.path.abspath('//') + "log.txt", "r+")
    # reroute stdout to the logfile
    sys.stdout = logfile
    return logfile

# Reads the file content and closes it
def readAndCloseLogs( logfile ):
    logfile.seek(0)
    logs = logfile.readlines()
    logfile.close()
    # Return stdout to its normal state
    sys.stdout = sys.__stdout__
    return logs

# Then wrap your operator between these two functions
logfile = openLogs()
# bpy.ops... # Put your operator here 
logs = readAndCloseLogs( logfile )

# The logs contains what the Operator has reported