[Cython] Feature Request: expand list/tuple in 'if (... in ...):' ...

[Christian Inci]

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On 01/24/2013 03:44 PM, Dag Sverre Seljebotn wrote:
> How do you know that INT_TUPLE isn't reassigned to something else?

On 01/24/2013 03:49 PM, Stefan Behnel wrote:
> This is not an optimisation as it might render the code incorrect. How can
> Cython know that you'll never change INT_TUPLE at runtime?

A good point. What's about something like final or const?

> However, if you use a literal list or tuple in place, this already works,
> i.e. the first example is equivalent to
> 
>     if j in (0x66, 0x67, 0x2e,
>              0x36, 0x3e, 0x26, 0x64,
>              0x65, 0xf2, 0xf3, 0xf0):
> 
> You actually get a C switch statement for it.

Thanks, this actually works. :-)

> 
> If you prefer keeping the set of integer values at a separate place, this
> should work:
> 
>     DEF INT_TUPLE = (0x66, 0x67, 0x2e,
>                      0x36, 0x3e, 0x26, 0x64,
>                      0x65, 0xf2, 0xf3, 0xf0)
> 
> (mind the upper case "DEF").

But this doesn't work. That's why I'm using 'cdef tuple'.

According to 'http://docs.cython.org/src/userguide/language_basics.html#compile-time-definitions', this will only work using int, long, float or str.
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