[PyKDE] Coerce QString to unicode or str?

[Phil Thompson]

On Friday 07 October 2005 5:42 pm, Nigel Stewart wrote:
> PyQt happily converts python strings and unicode strings
> into QString arguments for Qt API calls.  That's very
> convenient.
>
> In Python, string and unicode objects can be mixed,
>
> and are coerced as needed:
>  >> print type("hello" + unicode("world"))
>
> <type 'unicode'>
>
>  >> print type(unicode("hello") + "world")
>
> <type 'unicode'>
>
> What would be nice, would be similar handling for
>
> QString:
>  >> print type("hello" + qt.QString("world"))
>
> Exception: cannot concatenate 'str' and 'qt.QString' objects
>
>  >> print type(unicode("hello") + qt.QString("world"))
>
> Exception: coercing to Unicode: need string or buffer, qt.QString found
>
> Python provides 2.4 provides coersion for numeric
> types, but is deprecated.  The intention is that
> methods should explicitly deal with whatever type
> of argument is given, rather than depend on coersion.
>
>      "This section used to document the rules for coercion.
>       ... In Python 3.0, coercion will not be supported."
>
> http://www.python.org/doc/2.4.2/ref/coercion-rules.html
>
> That raises two questions - (1) would it be desirable for
> Python to quietly convert QStrings to unicode as needed,
> and (2) is it technically possible in Python 2.4, 3.x?
>
> A sip-based solution might be to provide SIP_PYUNICODE or
> SIP_PYSTRING as alternative return types to QString.
> But, I think it might be disruptive for the PyQt bindings
> to be taken in this direction...

It's a SIP limitation that will be fixed in the next version (in fact a 
partial implementation will be in tonight's snapshot).

Phil