[Python-Dev] PEP 334 - Simple Coroutines via SuspendIteration (original) (raw)
Clark C. Evans cce at clarkevans.com
Wed Sep 8 15:32:15 CEST 2004
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On Wed, Sep 08, 2004 at 09:26:03AM -0400, Clark C. Evans wrote: | On Wed, Sep 08, 2004 at 09:07:59AM -0400, Jp Calderone wrote: | | | | def somefunc(): | | raise SuspendIteration() | | return 'foo' | | | | def genfunc(): | | yield somefunc() || Interesting, but: | - somefunc is a function, thus SuspendIteration() should | terminate the function; raising an exception | - somefunc is not a generator, so it cannot be yielded.
It's too early for me to be posting; scrap the nonsense in this second point. I don't think this changes the suggestion below though.
|| However, perhaps something like...
|| def suspend(*args,**kwargs):
| raise SuspendIteration(*args,**kwargs)
| # never ever returns
|| def myProducer():
| yeild "one"
| suspend()
| yield "two"
|| Regardless, this is a side point. The authors of iterators that
| raise a SuspendIterator() will be low-level code, like a next()
| which reads the next block from a socket or row from a database
| query. In these cases, the class style iterator is sufficient.
|| The real point, is that user-level generators, such as this example
| from the PEP (which is detailed as a class-based iterator), should
| transparently handle SuspendIteration() by passing it up the generator
| chain without killing the current scope.
|| | def ListAlbums(cursor):
| | cursor.execute("SELECT title, artist FROM album")
| | yield '
| | for (title, artist) in cursor:
| | yield 'Title Artist %s %s
-- Clark C. Evans Prometheus Research, LLC. http://www.prometheusresearch.com/ o office: +1.203.777.2550 ~/ , mobile: +1.203.444.0557 // (( Prometheus Research: Transforming Data Into Knowledge \ , / - Research Exchange Database /\ - Survey & Assessment Technologies ` \ - Software Tools for Researchers ~ *
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