Dispatch App : Fix setting of dispatch plug from command line

[ivanimanishi]

The same dispatcher can be added to the dispatchers list multiple times, once from the dispatcher parameter, and again from the alternateDispatchers parameter.

That in turn resulted in the wrong dispatcher object being the one updated by the settings from the command line.

The fix here is to remove duplicate objects from the list, so there is only one dispatcher for a given name.

In our specific scenario, we were making the following sort of command line call:

gaffer dispatch -gui -tasks GafferJabuka.Nodes.Executable.InputProfileDispatcher -show InputProfileDispatcher -dispatcher Farm -settings -FarmDispatcher.farm.taskType '"InputProfileDispatcher"'

And the -FarmDispatcher.farm.taskType plug wasn't being set.

I considered a way not to add the same dispatcher twice, but couldn't find a nice way of doing that.

So instead I just remove the duplicates before processing the list further.

Checklist

• I have read the contribution guidelines.
• I have updated the documentation, if applicable.
• I have tested my change(s) in the test suite, and added new test cases where necessary.
• My code follows the Gaffer project's prevailing coding style and conventions.

[johnhaddon]

Thanks Ivan! I'm quitr happy to merge this as-is, but see what you think to the following :

I considered a way not to add the same dispatcher twice, but couldn't find a nice way of doing that.

I always considered Dispatcher.createMatching() to be a weird API addition. It's a trivial combination of registeredDispatchers() and StringAlgo::matchMultiple(), and its limited potential use cases don't justify cluttering the API with it. I think this has been borne out by the fact that we still only have one exact call to it after all these years, the one that is in the way here in the dispatch app.

So could we deprecate that, and do something like this instead?

if args["gui"].value and len( args["alternateDispatchers"] ) : 
    for name in Dispatcher.registeredDispatchers() :
         if name != dispatcherType and StringAlgo.matchMultiple( name, args["alternateDispatchers".value ) :
            dispatchers.append( Dispatcher.create( name )

It's slightly less code overall, lets us tidy up the API, and doesn't have the inelegant property of making things just to throw them away.

[ivanimanishi]

@johnhaddon , I've updated the PR following your suggestion.

Note that I haven't deprecated Dispatcher.createMatching(). I'll leave that to you.