[PyQt] Floats accepted for C++ ints?

[Florian Bruhin]

* Phil Thompson <phil at riverbankcomputing.com> [2016-07-05 22:18:16 +0100]:
> On 5 Jul 2016, at 9:51 pm, Florian Bruhin <me at the-compiler.org> wrote:
> > 
> > * Phil Thompson <phil at riverbankcomputing.com> [2016-07-05 18:33:37 +0100]:
> >> On 5 Jul 2016, at 6:22 pm, Florian Bruhin <me at the-compiler.org> wrote:
> >>> 
> >>> I've noticed Python floats are accepted when a C++ int is expected,
> >>> and simply truncated:
> >>> 
> >>> 	>>> from PyQt5.QtCore import QRect
> >>> 	>>> QRect(0.5, 0.5, 0.5, 0.5)
> >>> 	PyQt5.QtCore.QRect()
> >>> 	>>> QRect(1.5, 1.5, 1.5, 1.5)
> >>> 	PyQt5.QtCore.QRect(1, 1, 1, 1)
> >>> 
> >>> Is this intended behaviour? I'd have expected to raise a TypeError
> >>> (or, if anything, accept floats where .is_integer() is true)
> >> 
> >> It's standard Python behaviour. Floats implement __int__().
> > 
> > They also implement __str__, yet I obviously can't use them where Qt
> > expects a QString ;)
> > 
> > Isn't __int__ just there to customize what should happen when using
> > int(), just like __str__ is for str()?
> > 
> > float is not a subclass of int (i.e. isinstance(1.5, int) == False),
> > which is why this not raising a TypeError confuses me.
> 
> It's how PyLong_AsLong() works...
> 
> https://docs.python.org/3/c-api/long.html#c.PyLong_AsLong

Fair enough - I guess you could call PyLong_Check() on it first
("Return true if its argument is a PyLongObject or a subtype of
PyLongObject"), but it might also be too late to do that now?

Florian

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