py3 prepare some cases of zip behaviour

[chapoton]

as another step to py3

• take care of a reversed(zip()) in crystals
• make sure that factorizations can handle iterators

[chapoton]

New commits:

​3ba3a01

py3: handle some cases of zip behaviour

[jdemeyer]

As a general principle, I don't like code of the form

try:
    do_something()
except E:
    raise E("msg")

Especially if msg is meaningless or plain wrong. Just replace it by

do_something()

(I am talking about the raise TypeError("x must be a list") and also raise TypeError("exponents of factors must be integers"))

[jdemeyer]

In this case, you probably don't need the conversion to list at all, since enumerate() can handle iterables. This works without conversion to list:

sage: list(enumerate(xrange(5)))
[(0, 0), (1, 1), (2, 2), (3, 3), (4, 4)]

[jdemeyer]

Thinking even more about it, why not replace this whole block

        if not isinstance(x, (list, tuple)):
            try:
                x = list(x)
            except TypeError:
                raise TypeError("x must be a list")
        for i, t in enumerate(x):
            if not (isinstance(t, tuple) and len(t) == 2):
                raise TypeError("x must be a list of pairs (p, e) with e an integer")
            try:
                x[i] = (t[0], Integer(t[1]))
            except TypeError:
                raise TypeError("exponents of factors must be integers")

by the one-liner

x = [(p, Integer(e)) for (p,e) in x]

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​bbe4117

trac 22271 code simplified

[chapoton]

good idea, done.

[jdemeyer]

Let's wait for the patchbot.

[chapoton]

bot seems to be green