786509 - Remove broken, unused wildcard support from dbg-client.jsm's eventSource mixin

Status: RESOLVED FIXED

(DevTools :: Debugger, defect)

Description

[Jim Blandy :jimb]

Attachment: Remove support for wildcard event listeners from dbg-client.jsm's eventSource.

The support for wildcard event listeners is unused, and has never worked. The code to fire wildcard event listeners reads:

    if (this._listeners['*']) {
      listeners.concat(this._listeners['*']);
    }

However, Array.prototype.concat does not mutate 'this'; it returns a fresh array. So the wildcard listeners have never been called. The code has always read this way.

Since it's unused, I suggest we just take it out. It's easy enough to add back if we need it.

Comment 1

[Jim Blandy :jimb]

The patch also removes code to make addListener return without doing anything if the handler given is not a function. Since it's simply not correct to pass a non-function as the second argument, it seems to me this should either throw immediately, or at least let an error occur when we try to dispatch the event.

Comment 2

[Jim Blandy :jimb]

Attachment: Remove support for wildcard event listeners from dbg-client.jsm's eventSource.

Throw immediately given a non-function listener. Fix the other comment suggesting that a null event name is meaningful.

Comment 3

[Jim Blandy :jimb]

Try: https://tbpl.mozilla.org/?tree=Try&rev=2c1bdf01b554

Comment 4

[Panos Astithas (he/him) [:past] (please ni?)]

Comment on attachment 656279 [details] [diff] [review]
Remove support for wildcard event listeners from dbg-client.jsm's eventSource.

Review of attachment 656279 [details] [diff] [review]:
-----------------------------------------------------------------

Yes, agreed on all counts.

Comment 5

[Jim Blandy :jimb]

https://hg.mozilla.org/integration/mozilla-inbound/rev/28c0040c73a3

Comment 6

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/28c0040c73a3