[Qgis-developer] SIP API Update merged. Attention plugin authors

[Giuseppe Sucameli]

Hi Luigi (Gino),

On Fri, Jun 14, 2013 at 12:00 AM, Gino Pirelli <luipir at gmail.com> wrote:

> returnCheck = true
> try:
>       returnValue = variable
> except ValueError:
>       returnCheck = false
>

the previous code doesn't raise any ValueError without an explicit cast.

If conversion goes wrong you should get None (at least with the latest
API changes), so the check just becomes:

<code>
returnCheck = returnValue is not None
</code>


Another way is to add an explicit cast (e.g. to float):

<code>
try:
    returnValue = float(variable)
except ValueError:
    returnCheck = false
</code>


> ps: I hope my is English is enough understandable
>

it's surely better than mine ;)
Cheers.


>
> On Sun, Jun 9, 2013 at 4:42 PM, Matthias Kuhn <matthias.kuhn at gmx.ch>wrote:
>
>> Just found another case which requires special attention:
>>
>> Given a feature with myInt=5
>>
>> Old API:
>> > feat['myInt'].toFloat() / 10
>> > 0.5
>>
>> New API:
>> > feat['myInt'] / 10
>> > 0
>>
>> Better:
>> > float( feat['myInt'] ) / 10
>> > 0.5
>>
>> Or:
>> > feat['myInt'] / 10.0
>> > 0.5
>>
>> I guess that's not something we can fix in a generic way, but something
>> to keep in mind when updating a plugin.
>>
>> On Son 09 Jun 2013 16:38:09 CEST, Victor Olaya wrote:
>> > I find that same behaviour that Matthias confirms.
>> >
>> > I guess it should be fixed, since it forces developers to add extra
>> > code to handle that case, and it can be very confusing (all other
>> > Qvariants are removed, except in this case...)
>> >
>> > Hopefully it will be easy to fix.
>> >
>> > Thanks in advance!
>> > Victor
>> >
>> > 2013/6/9 Nathan Woodrow <madmanwoo at gmail.com>:
>> >> Ok I'll check it out and see if it can be converted.
>> >>
>> >> -- Nathan
>> >>
>> >>
>> >> On Mon, Jun 10, 2013 at 12:19 AM, Matthias Kuhn <matthias.kuhn at gmx.ch>
>> >> wrote:
>> >>>
>> >>> On Son 09 Jun 2013 16:02:57 CEST, Nathan Woodrow wrote:
>> >>>> Victor,
>> >>>>
>> >>>> Which code is returning a QVariant null?
>> >>>
>> >>> feat['myAttribute']
>> >>> returns QPyNullVariant for all features which have a NULL value in the
>> >>> field myAttribute.
>> >>>
>> >>> None would work for me as well. But I'm not sure, why PyQt introduced
>> >>> this new type. Maybe there is a reason?
>> >>>
>> >>> Matthias
>> >>>
>> >>>>
>> >>>> - Nathan
>> >>>>
>> >>>>
>> >>>> On Mon, Jun 10, 2013 at 12:01 AM, Victor Olaya <volayaf at gmail.com
>> >>>> <mailto:volayaf at gmail.com>> wrote:
>> >>>>
>> >>>>     I am checking the SEXTANTE adaptation to the new SIP API, and
>> >>>>     everything is fine. The only "strange" thing that I found is how
>> >>>> null
>> >>>>     values are handled when they appear in a vector layer field. It
>> >>>> seems
>> >>>>     that, in that case, a QVariant is still returned (particularly a
>> >>>>     QPyNullVariant object). Wouldn't it be better to return a Python
>> >>>> None
>> >>>>     instead, so in all cases Python values are returned?
>> >>>>
>> >>>>     Cheers
>> >>>>
>> >>>>     2013/6/9 Richard Duivenvoorde <rdmailings at duif.net
>> >>>>     <mailto:rdmailings at duif.net>>:
>> >>>>     > On 09-06-13 10:47, Nathan Woodrow wrote:
>> >>>>     >>
>> >>>>     >> Technically this can be done for smaller plugins like Borys
>> said.
>> >>>>     >>   Something like:
>> >>>>     >
>> >>>>     >
>> >>>>     > I think only for VERY small plugins. In the (not so very big
>> >>>>     plugins) I do
>> >>>>     > it was already getting messy.
>> >>>>     >
>> >>>>     > And by the why, a big thank you for all the great work and
>> >>>>     decisions being
>> >>>>     > done lately! I really think 2.0 will be great \o/
>> >>>>     >
>> >>>>     > Richard
>> >>>>     >
>> >>>>     >
>> >>>>     > _______________________________________________
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>> >>>>     > Qgis-developer at lists.osgeo.org
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>> >>>>
>> >>>>
>> >>>>
>> >>>>
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>> >>>
>> >>>
>> >>
>>
>>
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>
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-- 
Giuseppe Sucameli
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