On Thu, Jul 25, 2013 at 9:41 AM, Sean Vig <[email protected]> wrote:
> Most of the things in compatibility aren't too annoying, things that moved
> or are renamed, but otherwise function exactly the same.
>
> One big annoyance was working with unicode strings and checking unicode
> string output. The u'string' syntax doesn't work in 3.2 (though it was
> re-introduced in 3.3), and so a u('string') wrapper has to be used, but in
> pretty printing tests, that didn't work and I had to use an other u()
> function [1].
So we can view this as a temporary workaround for Python 3.2, that
eventually we'll drop in the future. A little annoying, but quite simple
syntax change.
>
> Using metaclasses is not straightforward; because the standard way to define
> metaclasses is different between 2 and 3, a completely different method has
> to be used [2] which isn't very clear.
So basically, whenever we declare a SymPy class
that uses metaclasses, instead of doing:
class Pi(NumberSymbol):
__metaclass__ = Singleton
...
we now have to do:
class Pi(with_metaclass(Singleton, NumberSymbol)):
...
In other words, if you don't use __metaclass__, then no change is necessary.
If you do use __metaclass__, then you have to understand what it is
doing anyway,
so typically you are not a Python beginner anymore at this point. And
in that case,
a simple syntax change is imho minor. It also doesn't seem to affect many
classes in sympy (fortunately).
>
> Dealing with map/range/filter was occasionally annoying, as they are now
> return iterables in 3, which is usually fine for things like `for ... in
> map/range/filter`, but would occasionally mean having to backtrack to find
> where assignments were made with these functions and not wrapped in
> `list()`.
This seems a minor.
Ondrej
>
> Sean
>
> [1] https://github.com/sympy/sympy/pull/2318/files#L290R22
> [2] https://github.com/sympy/sympy/pull/2318/files#L76R93
>
> On Thu, Jul 25, 2013 at 9:45 AM, Aaron Meurer <[email protected]> wrote:
>>
>> I'll ask here what I asked on the pull request. Can you give a list of
>> the things that we would have to do to support both. I'm concerned
>> about the annoyance factor here. Obviously, we've had a compatibility
>> file for some time, so we are no strangers to such things, but I'd
>> like to know what we'd be getting into here, beyond the obvious
>> print() instead of print.
>>
>> Aaron Meurer
>
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