[Twisted-Python] Re: Resource.render() returning NOT_DONE_YET

Clark C. Evans cce at clarkevans.com
Mon Apr 28 12:17:56 EDT 2003

On Mon, Apr 28, 2003 at 04:09:35PM +0000, Clark C. Evans wrote:
| I was just giving a quick Twisted tutorial to someone using
| twisted and as we were breaking page construction into more
| than one chunk... an unexpected stumbling block occurred --
| returning NOT_DONE_YET form the resource's render() function.
| I was thinking about two other options:
|   1.  Perhaps NOT_DONE_YET could just be None, this 
|       way, it can be the default return value.  As I'm
|       browsing through my code this is the most common
|       return... why not make it the default.

        Err, this isn't exactly what I was thinking.  What
        I was proposing...  if during the scope of the render()
        function, req.write() is called, then a None value
        would be an allowable return.   And if None is returned,
        req.finish() would be called automagically.

|   2.  Alternatively, allow a Deferred to be a return 
|       value.  Then the underlying caller can add 
|       result.finish() to the deferred chain.   This
|       has the advantage of not requiring finish() to
|       really be managed.   Either the return value is
|       a string, a Deferred, (or for backwards compatibiliy
|       NOT_DONE_YET).  In either of the primary cases,
|       result.finish() always gets called... thus making
|       it easier on newbies.
| Ideally, both of the above options could be used...
| Best,
| Clark

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