[Tutor] reassigning/replacing sys.stdout

[Luke Paireepinart]

Tony Cappellini wrote:
>
> I'm writing a python gui app that will call a python cmd line app. The 
> gui will take users input, pass it to the cmd line app, then display 
> the cmd app program output. The idea is to give users who aren't 
> comfortable with the cmd line a way to run the program, without having 
> to open a shell window (on Linux) or cmd prompt  (On Windows) and get 
> hung up on syntax or shell issues. It's a crutch.
>
> The author of the cmd line app suggested I temporarily replace 
> sys.stdout 'with a file descriptor class that can write directly to 
> the gui'.
> The author is now out of communications for a few weeks,  so I can't 
> elaborate.
>
> However, I've opened a file which writes to the disk, and replaced 
> that sys.stdout with that file descriptor.
> I can then close and open that file and have the output of his program.
> Now I can just put this in a textbox on the gui and display it to the 
> user.
>
> Writing to a file on disk, then reading it back in seems a bit clunky 
> to me.
> While I did somewhat do what the author had suggested (although I 
> didn't make a class out of the file descriptor), and it works, is 
> there a better way?
print 'bob'
is the same as
sys.stdout.write('bob')
sys.stdout.write('\n')

In python, since this 'sys....' function call doesn't check what type of 
object it's calling,
just that it has a method called 'write', you can write your own object 
and drop it in here.

E.G.

class GuiUpdater(object):
    def write(astring):
        #update your textbox here.

sys.stdout = GuiUpdater
print 'teststr'

Hmm, actually that might not work since it's not an instance of a class.
But that's the general idea/strategy.

HTH,
-Luke