On 2009-02-10, Albert Hopkins mar...@letterboxes.org wrote:
On Tue, 2009-02-10 at 12:50 -0800, Josh Dukes wrote:
I don't understand what you mean by this. But if you really want to
know if a generator is non-empty:
def non_empty(virgin_generator):
try:
virgin_generator.next()
quite simply...what???
In [108]: bool([ x for x in range(10) if False ])
Out[108]: False
In [109]: bool( x for x in range(10) if False )
Out[109]: True
Why do these two evaluate differently? I was expecting that they would
evaluate the same but the generator would return true *as soon as the
On Tue, Feb 10, 2009 at 11:15 AM, Josh Dukes josh.du...@microvu.com wrote:
quite simply...what???
In [108]: bool([ x for x in range(10) if False ])
Out[108]: False
This evaluates the list comprehension and creates an empty list, which
is considered boolean False by Python.
In [109]: bool( x
On Tue, 2009-02-10 at 11:15 -0800, Josh Dukes wrote:
quite simply...what???
In [108]: bool([ x for x in range(10) if False ])
Out[108]: False
In [109]: bool( x for x in range(10) if False )
Out[109]: True
Why do these two evaluate differently? I was expecting that they would
evaluate
The first example is a list. A list of length 0 evaluates to False.
The second example returns a generator object. A generator object
apparently evaluates to true. Your example is not iterating of their
values of the generator, but evaluating bool(generator_object) itself.
My feeling is
On Tue, 2009-02-10 at 12:50 -0800, Josh Dukes wrote:
The thing I don't understand is why a generator that has no iterable
values is different from an empty list. Why shouldn't bool ==
has_value?? Technically a list, a tuple, and a string are also objects
but if they lack values they're
On Tue, 10 Feb 2009 12:50:02 -0800, Josh Dukes wrote:
The thing I don't understand is why a generator that has no iterable
values is different from an empty list.
How do you know it has no iterable values until you call next() on it and
get StopIteration?
By the way, your has_values function
On Tue, Feb 10, 2009 at 1:57 PM, Steven D'Aprano
ste...@remove.this.cybersource.com.au wrote:
On Tue, 10 Feb 2009 12:50:02 -0800, Josh Dukes wrote:
The thing I don't understand is why a generator that has no iterable
values is different from an empty list.
How do you know it has no iterable
ahhh any! ok, yeah, I guess that's what I was looking for. Thanks.
On 10 Feb 2009 21:57:56 GMT
Steven D'Aprano ste...@remove.this.cybersource.com.au wrote:
On Tue, 10 Feb 2009 12:50:02 -0800, Josh Dukes wrote:
The thing I don't understand is why a generator that has no iterable
values is
Josh Dukes wrote:
I was actually aware of that (thank you, though, for trying to help).
What I was not clear on was if the boolean evaluation is a method of an
object that can be modified via operatior overloading (in the same way
+ is actually .__add__()) or not. Clearly __nonzero__ is the
On Tue, 2009-02-10 at 12:50 -0800, Josh Dukes wrote:
The thing I don't understand is why a generator that has no iterable
values is different from an empty list. Why shouldn't bool ==
has_value?? Technically a list, a tuple, and a string are also objects
but if they lack values they're
11 matches
Mail list logo
