Can I get the output of "print" statement in pythonw?

Question

pythonw.exe doesn't have a console so I can't see the output of print. But my program is OKAY in python.exe, failed in pythonw.exe. I just want to see the logs from python interpreter and the log printed by my "print" statement, is it doable?

Answer 1

You can globally redirect stdout by assigning to sys.stdout:

import sys
sys.stdout = open("mylog.txt", "w")

Then the rest of your program's stdout, including print statements, will go to mylog.txt.

Answer 2

You can redirect the output to any class that implements a .write method. For example, I redirect both sys.stdout and sys.stderr to a class that writes the results into a rich textbox, with the normal output in black and the errors in red.

logControl = None
def LogWrite(text, color):
    logControl.SetDefaultStyle(wx.TextAttr(color, wx.NullColour))
    logControl.WriteText(text)

class RedirectStdOut:
    def write(self,string):
        LogWrite(string, "BLACK")

class RedirectStdErr:
    def write(self,string):
        LogWrite(string, "RED")

....

    sys.stdout = RedirectStdOut()
    sys.stderr = RedirectStdErr()

In this case, logControl is just a reference to a rich textbox that I can assume exists. You could write to both the control and a file, redirect to dbgview or do pretty much anything you want with it.

Answer 3

You can redirect the output of print to any stream. For example

logfile = open("logfile.txt", "w")
print >>logfile, "This is a log test"

Although most of the time it would be more appropriate to use python's built-in logging facilities from the logging module.

Answer 4

I found that a plain print statement that is too long will crash the program. You need to redirect the output. To test this idea create a simple program

    import time
    time.sleep(5)

Save it as test.pyw. When you run this program it will show up on the task manager. Now modify it by adding a print statement. This text file has over 100 lines in it.

    import time
    string = ''
    filename = 'pathto/text.txt'
    f = open(filename,'r')
    for line in f:
            string = string + ' ' + line
    f.close()
    print string
    time.sleep(5)

The program will crash.