py3: make LazyString objects iterable

[nphilipp]

This is necessary so that Genshi > 0.7 can render LazyString objects with Python 3.

[amol-]

Can you point out a short example to reproduce the issue so that I can embed it in the test suite? (just using genshi+LazyString without a TGApp should suffice)

[nphilipp]

Here you go:

from genshi.template.markup import MarkupTemplate
from tg.util import LazyString

markup = """<b xmlns:py="http://genshi.edgewall.org/">${foo}</b>"""
template = MarkupTemplate(markup)
print(template.generate(foo=LazyString(lambda: "bar")))
...
TypeError: 'LazyString' object is not iterable

This will work:

from genshi.template.markup import MarkupTemplate
from tg.util import LazyString

class MyLazyString(LazyString):
    def __iter__(self):
        return iter(self.eval())

markup = """<b xmlns:py="http://genshi.edgewall.org/">${foo}</b>"""
template = MarkupTemplate(markup)
print(template.generate(foo=MyLazyString(lambda: "bar")))
...
<b>bar</b>

[amol-]

committed as 2c816b9