I'm not clear on the problem. Isn't it just a matter of doing:
def compute(self, pPlug, pDataBlock):
if pPlug == self.output_t_qqq :
# do math for the _qqq output attr.
It wasn't a matter of string concatenating being "illegal" inside a compute
function. Its just that you were trying to add together incompatible types.
A working equivalent of your example might look like this:
def compute(self, pPlug, pDataBlock):
params = ['qqq', 'rrr', 'sss', 'ttt']
for param in params:
if pPlug == getattr(self, 'output_t_%s' % param):
# do math for the _qqq output attr.
or
def compute(self, pPlug, pDataBlock):
params = set([
self.output_t_qqq,
self.output_t_rrr,
self.output_t_sss,
self.output_t_ttt,
])
if pPlug in params:
# do math for the _qqq output attr.
On Nov 26, 2013, at 8:47 PM, [email protected] wrote:
> Hey su, thanks for the note. Your explanation makes sense from a semantic
> perspective. My plugin has twelve outputs. I was looking for a way to
> structure my compute() so that evaluating one output would not mean
> evaluating all of them, for performance reasons. Your suggested solution
> would allow that I think, but at the cost of my compute() getting pretty
> bloated with repeated blocks of functionally equivalent code.
>
> It seems to me the trade-off is between inefficient code (in the sense of how
> much ink is being spilled) which provides very efficient compute() execution,
> versus efficient code where one generic compute function can handle every
> output - and evaluate every output, every time some input plug is dirtied and
> the node is evaluated.
>
> So taking this another step further: if dealing with an uninstanced class is
> a necessary condition for referring to a plug, are there any other ways to
> test the identity of the plug passed to compute()? A quick scan of the API
> docs suggests there is no other way than to refer to it explicitly, but I'd
> love to be proven wrong.
>
> Mitch
>
>
>
>
> On Monday, November 25, 2013 10:07:07 AM UTC-8, su wrote:
>> in your compute myClass is a (uninstanced) class not a string.
>>
>> anyway, the easiest way is just check the plug like:
>> if pPlug == myClass.output_t_qqq:
>>
>> do stuff
>>
>> elif pPlug == myClass.output_t_rrr:
>>
>> do other stuff
>>
>> ...
>>
>>
>>
>>
>> On 25 November 2013 11:26, <[email protected]> wrote:
>>
>> Hello everyone,
>>
>>
>>
>> I have a plugin that defines several output plugs:
>>
>>
>>
>> output_t_qqq = OpenMaya.MObject()
>>
>> output_t_rrr = OpenMaya.MObject()
>>
>> output_t_sss = OpenMaya.MObject()
>>
>> output_t_ttt = OpenMaya.MObject()
>>
>>
>>
>> These output plugs get added correctly as an attributes to the class, in the
>> nodeInitializer function:
>>
>>
>>
>> myClass.output_t_qqq = numericAttributeFn.createPoint( 'qqq_translate_out',
>> 'qqq_t_out' )
>>
>> numericAttributeFn.setWritable( False )
>>
>> numericAttributeFn.setStorable( False )
>>
>> numericAttributeFn.setHidden( True )
>>
>> numericAttributeFn.setReadable(True)
>>
>> myClass.addAttribute( myClass.output_t_qqq )
>>
>>
>>
>> etc...
>>
>>
>>
>> Here's my question: I want to optimize my compute function by executing a
>> particular block if the plug name is .._qqq, or .._rrr, etc. I thought I
>> could do this :
>>
>>
>>
>> def compute(self, pPlug, pDataBlock):
>>
>> params = ['qqq', 'rrr', 'sss', 'ttt']
>>
>> for param in params:
>>
>> if (pPlug == myClass + '.output_t_' + param):
>>
>> # do math for the _qqq output attr.
>>
>>
>>
>> However Maya complains, at the if statement:
>>
>>
>>
>> "unsupported operand type(s) for +: 'type' and 'str'"
>>
>>
>>
>>
>>
>> So.... performing string concatenation in an expression, inside compute() is
>> illegal in some way. What's the legal way of doing this?
>>
>>
>>
>> Mitch
>>
>>
>>
>> --
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>>
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>
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