[Qgis-developer] [QGIS-Processing] Define optional parameters in Script

[René-Luc Dhont]

Hi Victor,

I'm working on porting QGIS Processing to Web Processing Service, and I 
have found that all parameters in a QGIS Processing script are mandatory.
It would be useful to power define some parameters as optional.

I think that I can propose some code but I'd like to know what is your 
preferred way of defining optional parameters :
* an header line started by 'optional' with a list of parameter name 
separated by comma
##optional=SEGMENTS,DISTANCE
* an extra value at the end of the header line
##SEGMENTS=number 5 opt

Thanks