John Ehresman wrote:
On 4/26/13 12:50 PM, Hugo Parente Lima wrote:
How would converting integers into enums after checking that they
were valid cause a segfault?
After checking they are valid wont cause any problems, but checking
if they are valid on every function call seems like a unnecessary
overhead IMO, although I don't have numbers to prove this possible
overhead :-)
My point is about not doing the check plus converting every integer
with a reinterpret_cast.
Yes, not checking would be a problem. I tend to think the overhead
from checking would be negligible. Does anyone know if PyQt would
accept an integer in these cases?
I'm not sure if PyQt is doing anything different, but I've been using
SIP lately (for the new wxPython) and things like pickle or copy module
operations work fine with enum values. IIRC SIP implements each enum as
a class that derives from int and the enum values are instances of that
class. This lets there be some type checking when passing enum values
to a function, ensuring that the parameter is not an enum value from a
different enum class, but it is still more-or-less as fast as using a
plain int. It does allow plain ints to be passed as parameters for enum
args, so it isn't fool-proof, but it gets a long way down that path. It
seems like a good balance to me.
>>> f = wx.Frame(None)
>>> f.Show()
True
>>> wx.WindowVariant
<class 'wx._core.WindowVariant'>
>>> type(wx.WINDOW_VARIANT_SMALL)
<class 'wx._core.WindowVariant'>
>>> wx.WINDOW_VARIANT_SMALL
1
>>>
>>> f.SetWindowVariant(wx.WINDOW_VARIANT_SMALL)
>>> f.SetWindowVariant(1)
>>> f.SetWindowVariant(wx.SHOW_EFFECT_ROLL_TO_BOTTOM)
Traceback (most recent call last):
File "<input>", line 1, in <module>
TypeError: Window.SetWindowVariant(): argument 1 has unexpected type
'ShowEffect'
>>>
--
Robin Dunn
Software Engineer
Enthought, Inc.
[email protected]
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