[HasDefaultValue]

[jordan-walters]

We at Chamsys/Chauvet would really benefit from the addition of a HasDefaultValue() function on the IGdtfDmxChannelFunction interface. At present 0 (zero) is returned if there is a DefaultValue set to 0, or if there is no DefaultValue. If there is no DefaultValue we would then want to assign our own default value - depending on the Channel's attribute.

My code enhancement is based on the already existing IGdtfDmxChannel HasHighlight() function.

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[AndriiVoitenko]

Hi @jordan-walters , there is a logical difference between Highlight and Default: there are cases where Highlight from logical point of view make no sense. For example, attribute Pan, from logical point of view pan does not have Highlight value. And for such cases GDTF specification defines a special None value for Highlight xml attribute of DMX channel.

Xml attribute Default of channel function means “Default DMX value of channel function when activated by the control system”. Device can not be in undefined state, always when user activates channel function it should be in some defined state, otherwise visualizer and controller can not predict output. Therefore, Default value of Channel function is a mandatory one and can not have None as special value. And as @petrvanekrobe write you in #71, the solution is to extend specification with default for "Default" xml attribute which would be equal DMX From.

That’s why you pull request introduce a new functionality which collides with GDTF specification and can not be merged into master branch.