[Python-bugs-list] [ python-Feature Requests-778859 ] Make the generators working like Sather iterator

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Feature Requests item #778859, was opened at 2003-07-28 12:52
Message generated for change (Comment added) made by shasckaw
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Shasckaw Lionfaith (shasckaw)
Assigned to: Nobody/Anonymous (nobody)
Summary: Make the generators working like Sather iterator

Initial Comment:
Primarly, it would only be a syntaxic sugar. But it can
lead to some unexpected opitmisations.
The feature would allow this:

def upto(first, last):
        x=first
        while x<=last:
                yield x
                x=x+1

x=upto(1, 10)

try:
        while 1:
                print x.next()
except StopIteration:
        print "End of loop"

To be written like in Sather or something near it:

def upto(first, last):
#same definition as above

loop:
        print upto!(1, 10)
finally:
        print "End of loop"

As you can see, it's shorter, smarter, and more easy to
understand. The '!' in upto!(1, 10) is important to
emphasize its rôle as a generator. The creators of
Sather tell that this technique can lead to a very high
optimisation of loops.
I hope that this request will be deeply studied because
it is really worth of it.

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>Comment By: Shasckaw Lionfaith (shasckaw)
Date: 2003-07-28 15:23

Message:
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My example was too simple, sorry.
Here is a doc page about satheric iterators:
http://www.gnu.org/software/sather/Doc/tutorial.html/iterators873.html
And the next one is also pretty interesting.

With the satheric way to write it, one would be able to do this:
loop:
        a=range!(1,10)
        if test(a):
                b=range!(1,10)
        print "("+ a + "," + "b" + ")"

My error is repaired now! :)
The first iterator to stop stop the loop.

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Comment By: Barry A. Warsaw (bwarsaw)
Date: 2003-07-28 14:22

Message:
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The Pythonic way to write the latter (after the def) is:

for x in upto(1, 10):
  print x
else:
  print 'end of loop'


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