[Python-Dev] bool conversion wart?

[Ben Wing]

On 2/22/07, Neal Becker <ndbecker2 at gmail.com> wrote:
>
> Mike Klaas wrote:
>
> > On 2/22/07, Neal Becker <ndbecker2 at gmail.com> wrote:
> >
> >> Well consider this:
> >> >>>str (4)
> >> '4'
> >> >>>int(str (4))
> >> 4
> >> >>>str (False)
> >> 'False'
> >>
> >> >>>bool(str(False))
> >> True
> >>
> >> Doesn't this seem a bit inconsisent?
> >
> > Virtually no python objects accept a stringified version of themselves
> > in their constructor:
> >
> >>>> str({})
> > '{}'
> >>>> dict('{}')
> > Traceback (most recent call last):
> >   File "<stdin>", line 1, in <module>
> > ValueError: dictionary update sequence element #0 has length 1; 2 is
> > required
> >>>> str([])
> > '[]'
> >>>> list('[]')
> > ['[', ']']
> >
> > Python is not Perl.
> >
> Except, all the numeric types do, including int, float, and complex.  But
> not bool.  In fact, this is not just academic.  The fact that other
> numeric
> types act this way leaves a reasonable expectation that bool will.
> Instead, bool fails in _the worst possible way_: it silently gives a
> _wrong
> result_.


i agree with mike; it would just be asking for trouble. (have you ever been
bitten by the Perl behavior where the string '0' is considered false?  it's
a nasty, nasty problem to debug.)

neal, you may be confusing the concepts of "convert data from one type to
another" and "read the printed representation of data".


ben
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