Idea: Use __or__ for chaining

[rconradharris]

For the common case linking stdout to stdin of another process, we could use the 'pipe' syntax from shells by overloading the __or__ method.

Part of me thinks this is way too clever (in a bad way)... the other half thinks this would be really awesome/elegant.

Just an example:

class PipeCommand(object):
    def __init__(self, cmd):
        self.cmd = cmd
    def __repr__(self):
        return self.cmd
    def __or__(self, other):
        return PipeCommand('|'.join([self.cmd, other.cmd]))                                                                                                                                                        

def run(cmd):
    return PipeCommand(cmd)

print run('cat') | run('wc -l')

[rubik]

+1 it really resembles the already established shell syntax, so why not?

[shrayasr]

+1 this feels too good to be true. It does resemble the shell syntax a lot and makes a lot of sense to do it, but we end up overloading the __or__ operator which just leaves me thinking about the right way.

Since this is for humans, i guess we can afford to break some rules?

[geerk]

Why not just use plumbum?:

>>> chain = ls["-a"] | grep["-v", "\\.py"] | wc["-l"]
>>> print chain
/bin/ls -a | /bin/grep -v '\.py' | /usr/bin/wc -l
>>> chain()
u'13\n'

[rconradharris]

@geerk Interesting! Didn't know about that.

[kennethreitz]

I was considering something like this as well. I was thinking of this syntax, however:

>>> uptime.stdout >> cowsay.stdin

I like the pipe idea. Fitting, due to the name of the library :)

Either way, we need a method first that works, then we can look at making something like this, maybe :)

[shrayasr]

I was considering something like this as well. I was thinking of this syntax, however:

>>> uptime.stdout >> cowsay.stdin

HMMM. If we are doing something like this, then the | makes more sense IMO.

Either way, we need a method first that works, then we can look at making something like this, maybe :)

Agreed 👍 This is syntactic sugar

[ssebastianj]

And maybe the chain could be indexable:

>>> print(chain)
>>> <process('uptime') | process('cowsay')>
>>> print(chain[0])
>>> <process('uptime')>
>>> chain[0] = process('uname')
>>> print(chain)
>>> <process('uname') | process('cowsay')>

[hjwp]

For the curious, I had a crack at getting the | / __or__ thing working: #10