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Groups > comp.lang.python > #39967
| From | "Colin J. Williams" <cjw@ncf.ca> |
|---|---|
| Newsgroups | comp.lang.python |
| Subject | Re: yield expression |
| Date | 2013-02-26 11:34 -0500 |
| Organization | National Capital Freenet, Ottawa, Ontario, Canada |
| Message-ID | <kgio69$5i7$1@theodyn.ncf.ca> (permalink) |
| References | <d7760f61-08dd-4186-8844-5f8415773a49@googlegroups.com> |
On 24/02/2013 7:36 PM, Ziliang Chen wrote: > Hi folks, > When I am trying to understand "yield" expression in Python2.6, I did the following coding. I have difficulty understanding why "val" will be "None" ? What's happening under the hood? It seems to me very time the counter resumes to execute, it will assign "count" to "val", so "val" should NOT be "None" all the time. > > Thanks ! > > code snippet: > ---- > def counter(start_at=0): > count = start_at > while True: > val = (yield count) > if val is not None: > count = val > else: > print 'val is None' > count += 1 Perhaps it's becaoue (teild count) is a statement. Statements do not return a value. Colin W. >
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yield expression Ziliang Chen <zlchen.ken@gmail.com> - 2013-02-24 16:36 -0800
Re: yield expression "Colin J. Williams" <cjw@ncf.ca> - 2013-02-26 11:34 -0500
Re: yield expression Ian Kelly <ian.g.kelly@gmail.com> - 2013-02-26 09:50 -0700
Re: yield expression Dave Angel <davea@davea.name> - 2013-02-26 12:05 -0500
Re: yield expression "Vytas D." <vytasd2013@gmail.com> - 2013-02-26 17:07 +0000
Re: yield expression "Colin J. Williams" <cjw@ncf.ca> - 2013-02-26 13:44 -0500
Re: yield expression Dave Angel <davea@davea.name> - 2013-02-26 21:59 -0500
Re: yield expression "Colin J. Williams" <cjw@ncf.ca> - 2013-02-26 13:44 -0500
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