Greg Ewing wrote:
But if the docs don't mention anything about true or
false values for some particular type, one tends to
assume that all values are true, as is the default
for user-defined classes.
The tutorials and such stress that python doesn't
typically care about a specific True or
On 9/22/05, Jim Jewett [EMAIL PROTECTED] wrote:
Is there anything left? is a pretty analogy for iterators,
But unmaintainable for iterators in general. This was considered ad
nauseam when iterators were initially introduced, and it was an
explicit decision *not* to provide an API to look ahead.
Jim Jewett wrote:
Is there anything left? is a pretty analogy for iterators,
particularly since the examples tend to start with list
or file iterators.
But this can't be supported by all iterators, so it would
be something special to these iterators.
Keeping track of the peculiarities of
[Guido van Rossum]
Could you at least admit that this was an oversight and not try to
pretend it was intentional breakage?
Absolutely. I completely missed this one.
Raymond
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Raymond Hettinger wrote:
The Boolean value of an
iterator is certainly not promised by the iterator protocol as specified
in the docs or the PEP.
But if the docs don't mention anything about true or
false values for some particular type, one tends to
assume that all values are true, as is the
On 9/21/05, Raymond Hettinger [EMAIL PROTECTED] wrote:
[Guido van Rossum]
Could you at least admit that this was an oversight and not try to
pretend it was intentional breakage?
Absolutely. I completely missed this one.
Thanks; spoken like a man.
I strongly feel that this needs to be
[Guido]
I strongly feel that this needs to be corrected in 2.5. Iterators
should have neither __len__ nor __nonzero__.
Right. I'll get it fixed-up.
[Terry Reedy]
I presume there were two reasons: internal efficiency of
preallocations
(list(some_it) for example)
[Guido]
This could
I just finished debugging some code that broke after upgrading to
Python 2.4 (from 2.3). Turns out the code was testing list iterators
for their boolean value (to distinguish them from None). In 2.3, a
list iterator (like any iterator) is always true. In 2.4, an exhausted
list iterator is false;
On Tuesday 20 September 2005 17:49, Guido van Rossum wrote:
I realize that this was a deliberate feature, and that it exists in
2.4 as well as in 2.4.1 and will in 2.4.2; yet, I'm not sure I *like*
I wasn't paying any attention at the time, so I don't know what was discussed.
Some
Fred L. Drake, Jr. wrote:
On Tuesday 20 September 2005 17:49, Guido van Rossum wrote:
I realize that this was a deliberate feature, and that it exists in
2.4 as well as in 2.4.1 and will in 2.4.2; yet, I'm not sure I
*like*
I wasn't paying any attention at the time, so I don't know
On 9/20/05, Delaney, Timothy (Tim) [EMAIL PROTECTED] wrote:
In any case, it's simple to get the 2.3 behaviour back - just add
__nonzero__. I think that could validly be considered a bugfix.
Alas not -- it would still be a functionality change relative to 2.4 and 2.4.1.
Also, an object whose
[Guido]
I just finished debugging some code that broke after upgrading to
Python 2.4 (from 2.3). Turns out the code was testing list iterators
for their boolean value (to distinguish them from None). In 2.3, a
list iterator (like any iterator) is always true. In 2.4, an exhausted
list
Guido van Rossum [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
I just finished debugging some code that broke after upgrading to
Python 2.4 (from 2.3). Turns out the code was testing list iterators
for their boolean value (to distinguish them from None).
This seem unnecessarily
On 9/20/05, Raymond Hettinger [EMAIL PROTECTED] wrote:
[Guido]
I just finished debugging some code that broke after upgrading to
Python 2.4 (from 2.3). Turns out the code was testing list iterators
for their boolean value (to distinguish them from None). In 2.3, a
list iterator (like any
On 9/20/05, Terry Reedy [EMAIL PROTECTED] wrote:
I presume there were two reasons: internal efficiency of preallocations
(list(some_it) for example)
This could have been implemented without making the implementation
details public.
and letting people differentiate iterator with
something
Guido van Rossum wrote:
I just finished debugging some code that broke after upgrading to
Python 2.4 (from 2.3). Turns out the code was testing list iterators
for their boolean value (to distinguish them from None). In 2.3, a
list iterator (like any iterator) is always true. In 2.4, an
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