On 03:33 pm, terry@jon.es wrote:

Is there a reason why the Deferred class doesn't have a tee method like the following (untested)?

def tee(self, d): def _cb(arg): d.callback(arg) return arg

def _eb(arg): d.errback(arg) return arg

return self.addCallbacks(_cb, _eb)

I suppose it could be called teeDeferred to correspond to chainDeferred. And I guess it's clear what it does and why it's quite different from chainDeferred. I at least would find it quite useful.

We implemented this 5 or 6 times at Divmod. The most recent incarnation looks like this: http://divmod.org/trac/browser/trunk/Epsilon/epsilon/pending.py I admit that I'd probably find it about as useful as I find explicit calls to Deferred.chainDeferred - perhaps even slightly more so. Though that's a low bar, I can't remember the last time I explicitly called chainDeferred; it's probably been a couple years. Not to say it's a bad idea, but I don't think it's _obviously_ a great idea. If someone wanted to contribute a documented, tested implementation, particularly with examples of common patterns that it simplifies, then you could probably convince someone to commit it. Jean-Paul

On 03:33 pm, terry@jon.es wrote:

Is there a reason why the Deferred class doesn't have a tee method like the following (untested)?

def tee(self, d): def _cb(arg): d.callback(arg) return arg

def _eb(arg): d.errback(arg) return arg

return self.addCallbacks(_cb, _eb)

I suppose it could be called teeDeferred to correspond to chainDeferred. And I guess it's clear what it does and why it's quite different from chainDeferred. I at least would find it quite useful.

We implemented this 5 or 6 times at Divmod. The most recent incarnation looks like this: http://divmod.org/trac/browser/trunk/Epsilon/epsilon/pending.py I admit that I'd probably find it about as useful as I find explicit calls to Deferred.chainDeferred - perhaps even slightly more so. Though that's a low bar, I can't remember the last time I explicitly called chainDeferred; it's probably been a couple years. Not to say it's a bad idea, but I don't think it's _obviously_ a great idea. If someone wanted to contribute a documented, tested implementation, particularly with examples of common patterns that it simplifies, then you could probably convince someone to commit it. Jean-Paul