No possibility to use multiple signal names

[niieani]

@jdanyow asked for a use case, so here's an example:

HTML (task.html):

<div if.bind="tags | containsTag: 'test' ">
    (...)
</div>

There are two things that can trigger a change of the tags property in the view model - either the task gets changed (somebody adds or removes a tag in it's view-model) or somebody renames one of the existing tags globally. In both of those instances I would like the binding to get reevaluated, because its value might have changed. I can send out signals in both instances (i.e. a signal for the specific task changing it's tags and a global app signal for the changes in tags). Therefore I'd like to be able to specify multiple signal names, lets say something like:

<div if.bind="tags | containsTag: 'test' & signal: [ 'global-tags-renamed', 'task-change-' + id ] ">
    (...)
</div>

Now the binding should get reevaluated when either of those signals gets sent.

[EisenbergEffect]

@jdanyow Couldn't the signal behavior be used multiple times?

[niieani]

@EisenbergEffect No, this gives an error A binding behavior named "signal" has already been applied.

[EisenbergEffect]

@jdanyow Would it be possible to make multiple instances of signal possible? If not, could we enable the signal behavior to receive either a signal name or an array of signals? What are your thoughts?

[niieani]

I've made a non-breaking pull request that fixes this with rest parameters (all additional parameters are treated additional signal names). #172

[jdanyow]

@EisenbergEffect / @niieani - I was thinking the same as @niieani: update the behavior such that it accepts multiple name arguments.

@niieani: thanks for the PR! Could you please make a few changes so we can merge it:

1. Please follow the commit message guidelines (in contributing.md). This enables us to automate the production of release notes among other things.
2. Please change ...args to the old-school arguments style. This is a hot code path so we can't afford the overhead of the transpiled ...args code. Here's what I mean
3. Please update the tests for the SignalBindingBehavior. The tests for the behaviors are kind of smelly, I can help with this if you get stuck or need a hand.

[niieani]

@jdanyow Sure, I'll do that when I get a moment.
@EisenbergEffect I was looking for some contributing guidelines (in many places, such as a link in the main README.md and in the Docs) before sending the PR, but I couldn't find anything aside from the information that signing the License is required. Perhaps it could be made clearer in the docs and/or the main readme that there is something like contributing.md and where to find it?