On 2/19/2010 12:44 PM, Stephen Hansen wrote:

Much to my embarrassment, sometime last night I realized I was being a
complete idiot, and the 'correct' way to handle this in my scenario is
really just:

def initialize():
     # do one time processing here

     return []

A generator is just a callable that returns an iterator, after all.

Confusing generators and generator functions is, well, confusing.
For future reference, and clarity of communication in Pythonland,

generator function: function that produces a generator when called; if python coded, its body contains 'yield'.

generator: iterator produced by a generator function; has .__next__ and self-returning .__init__, like all other iterators.

generator expression: an expression that evaluates to a generator; the expression is used to create a temporary anonymous generator function that is called to produce the generator and is then discarded.

>>> def gf(): yield 1

>>> gf
<function gf at 0x00F5F4B0>
>>> g=gf()
>>> g
<generator object gf at 0x00F5BE40>
>>> ge = (1 for i in [1])
>>> ge
<generator object <genexpr> at 0x00F5BFD0>
>>> dir(ge)
[..., '__iter__', ..., '__next__', ...]

So, when you said that you send 'generators' to your core system, when you meant 'generator functions', we were understanably confused. (Your core system should accept iterator classes also, unless it specifically checks to avoid duck typing.)

Terry Jan Reedy

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