Description

generator wrapper
In Pywikibot bots, BaseBot.run() assumes that self.generator is a mutable attribute, and may wrap it into a generator if it is only an iterable:

if not isinstance(self.generator, Generator):
    self.generator = (item for item in self.generator)

If generator is implemented as a @property without a setter, this breaks when wrapping is required, because run() attempts to assign to it and fails with:

AttributeError: property has no setter

generator.close()
A property may return a new generator instance on each access. This leads to inconsistent behavior:
run() may operate on one instance. self.generator.close() may affect a different instance. As a result: close() does not reliably stop iteration.

Expected behavior
run() must be able to assign a wrapped generator when needed. self.generator.close() must act on the active iterator.

Suggestions

• Document that generator must be a settable attribute holding a stable iterator instance, not a property.
• Warn when a property is detected.
• re-implement the stop method like in rPWBCe1077727c3b (3.0.20200111) T198801, deprecated in rPWBC8d9bae8486 (4.1) and removed with rPWBC402abb24 (7.0)
• use class tools.collections.GeneratorWrapper
• A generator function or method works as expected when assigned as follows:

def __init__(self):
    self.generator = self.generator()

def generator(self):
    yield

Usualy an external generator function is passed to the BaseBot via generator option like

gen_factory = pagegenerators.GeneratorFactory()
bot = MyBot(generator=gen_factory.getCombinedGenerator())
bot.run()

If an internal generator should be used, then

• it should not be a property but a function or a method. It should be assigned to the generator variable. Maybe if the Bot should provide its own generator, it should have a different identifier.
• if it is a property, the generator.close() method cannot be used. A (deprecation) warning should be thrown.