dataCallback, shouldSendCallback are passed prior callback as 2nd arg

[benvinegar]

Fixes #428 (and eventually #477)

Now you can do the following for both setDataCallback and setShouldSendCallback:

Raven.setDataCallback(function (data, priorDataCallback) {
  if (priorDataCallback) {
    data = priorDataCallback(data);
  }
  data.message = 'derp';
  return data;
});

This way it is possible to preserve OR override the behavior of any previously set callback, without adding new API methods (e.g. addDataCallback and addShouldSendCallback). It also lets subsequent callbacks mutate data before or after the prior callback is invoked, which the add API is not capable of doing (execution would be serial FIFO).

I'm not 100% on doing this, but I think it could be a satisfactory solution – especially since we've gone this far without it. Would love to get the community's feedback.

cc @mattrobenolt @nevir @mitsuhiko

[nevir]

This way it is possible to preserve OR override the behavior of any previously set callback, without adding new API methods (e.g. addDataCallback and addShouldSendCallback).

Yay! Much better

I'm not 100% on doing this, but I think it could be a satisfactory solution – especially since we've gone this far without it. Would love to get the community's feedback.

It would definitely cover my needs for #626

[mattrobenolt]

🍪

[mitsuhiko]

🍪