Odd ValueError using float

[Chris Angelico]

On Sun, Mar 15, 2015 at 2:28 AM, emile <emile at fenx.com> wrote:
> It ran almost to completion before generating the error again --
>
> (Pdb) decval
> '4'
> (Pdb) type(decval)
> <type 'str'>
> (Pdb) len(decval)
> 1
> (Pdb) int(decval)
> *** ValueError: invalid literal for int() with base 10: '41.700000000000003'
>
> So there's still something amiss.

Compare these two lines' outputs:

print("str %d, int %d" % (id(str), id(int)))
print("str %d, int %d" % (id(type("")), id(type(0)))

Any difference in id would indicate that the names have been shadowed
- seems unlikely, but worth checking. And then, just to be absolutely
sure:

type(decval) is type("")

There is another, and very nasty, possibility. If you're working with
a C extension that has a refcount bug in it, all sorts of bizarre
things can happen - crucial type objects getting garbage collected,
objects getting disposed of and others taking their places, all kinds
of weird and wonderful things. Normally that'll eventually cause a
crash, but who knows...

ChrisA