[Fab-user] Can't find in the docs, return codes

[Eric Brunson]

I'm hoping to start a discussion of behavior that would aid in implementing flow control.  I've only been using fabric for a couple of months, so maybe I just need some education on better coding patterns.

What I'd like to be able to do is something like this:

def remove_backups(path):
    with settings(warn_only=True), hide('warnings'):
        result = run('[ -d %s ]' % path)
        if ! result.error_code:
            with cd(path):
                run('rm *.bak')

Or possibly:

def remove_backups(path):
    try:
        run('[ -d %s ]' % path)
    except NonZeroExitCode:
        print("no backup dir")
        return

    with cd(path):
        run('rm *.bak')
                

I end up having to do something like this:

def remove_backups(path):
    with settings(warn_only=True), hide('stderr','warnings'):
        result = run('[ -d %s ] && echo true' % path)
    if result == 'true':
        run('rm *.bak')

Which is less than pythonic.

Has there ever been discussion of throwing exceptions or handling exit codes rather than the default "Abort unless otherwise instructed?" tactic as it currently exists?  Constructing intelligent flow control gets really messy in the current implementation.

Other than that, I've been using the crap out of the application and think it's great.  Thanks for all the hard work.

Sincerely,
e.