[Python-Dev] infinities

[Bob Ippolito]

On 11/26/06, tomer filiba <tomerfiliba at gmail.com> wrote:
> i found several places in my code where i use positive infinity
> (posinf) for various things, i.e.,
>
>     def readline(self, limit = -1):
>         if limit < 0:
>             limit = 1e10000 # posinf
>         chars = []
>         while limit > 0:
>             ch = self.read(1)
>             chars.append(ch)
>             if not ch or ch == "\n":
>                 break
>             limit -= 1
>         return "".join(chars)
>
> i like the concept, but i hate the "1e10000" stuff... why not add
> posint, neginf, and nan to the float type? i find it much more readable as:
>
>     if limit < 0:
>         limit = float.posinf
>
> posinf, neginf and nan are singletons, so there's no problem with
> adding as members to the type.

sys.maxint makes more sense there. Or you could change it to "while
limit != 0" and set it to -1 (though I probably wouldn't actually do
that)...

There is already a PEP 754 for float constants, which is implemented
in the fpconst module (see CheeseShop). It's not (yet) part of the
stdlib though.

-bob