[Python-ideas] IntFlags

[Neil Girdhar]

On Sat, Mar 7, 2015 at 1:51 PM, Ethan Furman <ethan at stoneleaf.us> wrote:

> On 03/07/2015 10:21 AM, Neil Girdhar wrote:
> > On Sat, Mar 7, 2015 at 10:05 AM, Ethan Furman wrote:
>
> >> or, even more illustratively, instead of:
> >>
> >>   x = Stat(some_Stat_value_from_somewhere)
> >>   x &= ~Stat.NOEXEC  # to clear the bit
> >>
> >> we can have:
> >>
> >>   x = Stat(some_Stat_value_from_somewhere)
> >>   x.NOEXEC = False  # much more readable
> >
> > Yes, +1
>
> >> Drat.  Instances of Stat would not be immutuable, but that means they
> can't be thin wrappers around `int`, doesn't it?
> >> Which also means more work around C call sites.  Drat and double-drat.
> >
> > Can't your C call sites cast the object to int?
>
> They could, but then you no longer have a drop-in replacement, which is
> what IntEnum is.  Plus it's a hassle.  So
> IntFlag (or whatever it's called) would to be immutable, which means no
> neat tricks like `obj.bit_name = False`.
>

A drop-in replacement for what?  Is there a lot of Python code that
manipulates flags that you expect people to convert to IntFlags from int?
Isn't the point of IntFlags for writing new code?


> > Why do you need ~ at all?  Do any API calls that you want to make want
> the inverted
> > flags?  Isn't the only point of inverting the bits in order to clear a
> field?
>
> Hopefully somebody else can address this point.
>
> --
> ~Ethan~
>
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