Observer plugins

[crownedgrouse]

This PR allow to add third party wx user interface plugins in Observer.
Plugins have to be declared in observer configuration.
Plugin can receive current observed node as start argument if needed.

[codeadict]

Very nice! Will be great to have a simple example for this.

[crownedgrouse]

Well, working on one. First step was to allow plugin.

[hyloong]

Any one can look my question? Thanks.
https://stackoverflow.com/questions/52268503/erlang-memory-grow-up-when-cl-file

[crownedgrouse]

Please send your questions on erlang mailing list, slack or bugs.erlang.org. Not the right place.

[crownedgrouse]

@codeadict I just pushed an example in commit 590eda0

[codeadict]

Maybe this should go outside in Bold or as a warning. What do you think?

[codeadict]

Like:

<warning>
  <p>To prevent the observer from being closed, please do not call
  <c>wx:destroy()</c> from your plugins.</p>
</warning>

[crownedgrouse]

I will consider this

[codeadict]

Hey, it looks very clear to me, will try compiling and adding this sample plugin tomorrow.

[essen]

Why the limitation on 10 plugins? If a limitation is needed, maybe it should be 10 active plugins, with some UI to enable/disable plugins. If there is already this and I missed it, please disregard.

Otherwise I like this idea very much, being able to add Cowboy/Ranch-specific info to Observer has been on the back of my mind for a while.

[dgud]

Please fix travis errors above: (dialyzer, doc)
Remove whitespace fixes on otherwise untouched lines, causes unnecessary diffs.
Use try-catch instead of catch, catch usage is discouraged and should be avoided in new code.

[crownedgrouse]

@essen menu entries in wx are handled as integers and event match needs to checks that this ID integer is a plugin menu (and not another ID for another menu), so needs to limit the number between a lower and upper bound (declared as defines in beginning of code). 10 is not a limit, it was arbitrary chosen. I can increase this, but maybe need @dgud opinion. As plugins are declared in observer config, I'm not sure how I can add an UI to tell that this plugin is active or not. Simply add only useful plugin in config for your node ?

[crownedgrouse]

@dgud thanks for the feedback. Indeed my editor has a diff tool that do not care of trailing whitespace... need to fix this config.

[crownedgrouse]

@dgud fixes are squashed. CI seems OK.

[dgud]

I don't like (nor understand) the usage of runtime_tools env, why can't you use observers environment.

[crownedgrouse]

Maybe I miss something but observer is not an application but comes with runtime_tools? Tell me if I m wrong

[dgud]

The observer gui is part of the observer application, observer uses runtime_tools but it also uses stdlib and kernel and wx.

[crownedgrouse]

Hum. I missed that observer is an application indeed. OK I will change that like it would have been since the beginning

[crownedgrouse]

I was confused with the fact that runtime_tools need to be part of a release for node to be observed by observer. Sorry

[crownedgrouse]

Fixed and squashed

[dgud]

I have thought some on this PR and reached the conclusion that I want something better where
the plugin api allows to add new tabs and not just pop up a new window.

I'm not against a plugin-api but want something better.

I'm closing this for now.

[essen]

Agree, need tabs! Let's make this happen.