Bluebird config not allowed when promises already in use

[stsje]

I'm submitting a bug report

• Library Version:
  0.21.0
• Browser:
  Firefox, Edge, IE 11

Current behavior:
An error is thrown if you enable bluebird's cancellation option: cannot enable cancellation after promises are in use. The error doesn't occur in Chrome.

A newly created CLI project has the bluebird configuration in main.js.

Example configuration in main.js that fails at startup:

import environment from './environment';

//Configure Bluebird Promises.
//Note: You may want to use environment-specific configuration.
Promise.config({
  warnings: {
    wForgottenReturn: false
  },
  cancellation: true
});

export function configure(aurelia) {
  aurelia.use
    .standardConfiguration()
    .feature('resources');

  if (environment.debug) {
    aurelia.use.developmentLogging();
  }

  aurelia.start().then(() => aurelia.setRoot());
}

Expected/desired behavior:
A newly setup project should allow any bluebird configuration options without failing.

The aurelia-bootstrapper module seems to be using promises in any other browser than Chrome before main.js is loaded.

One option is to change the bootstrapper, so it doesn't use promises. This will allow us to use the current clean setup, that is easy for people to understand.

Another option, which is our current fix, is to configure bluebird in index.html. Our index file is then changed to:

<!--<script src="dist\vendor-bundle.js" data-main="aurelia-bootstrapper"></script>-->
<script src="dist\vendor-bundle.js"></script>
<script>
  requirejs.config({
    skipDataMain: true
  });

  // Configure Bluebird Promises.
  Promise.config({
    warnings: {
      wForgottenReturn: false
    },
    cancellation: true
  });

  require(['aurelia-bootstrapper']);
</script>

Note that the requirejs config isn't actually needed, but it still might be a good idea to tell it not to look for data-main.

[EisenbergEffect]

It's not possible to remove promise use from the bootstrapper.

[stsje]

Could we then change the default CLI project setup, so it configures bluebird before requiring bootstrapper?

[EisenbergEffect]

It's possible. That's more complicated though because it would involve leaking module loader details into the index.html, which is something we would rather not do.

[EisenbergEffect]

PRs are welcome if we can find a good solution.

[stsje]

I'm not sure if the data-main attributes qualifies as a module loader dependency, since it wouldn't hinter other module loaders from working.
An abstraction will be needed in the CLI if data-main is seen as a module loader dependency.

How about doing the following, where you don't find any requirejs specific code in index.

    <script src="dist\vendor-bundle.js" data-main="aurelia-bootstrapper"></script>
    <script>
      // Configure Bluebird Promises.
      Promise.config({
        warnings: {
          wForgottenReturn: false
        },
        cancellation: true
      });
    </script>

I really don't like adding a pre-configuration step before aurelia-bootstrapper. It seems cleaner to have your configuration inside main.js. Right now I don't see any other way for bluebird promises.

Also I'm worried about any race conditions with the above. With requirejs it doesn't seem to be a problem, since it has to wait on the load event.

[EisenbergEffect]

Will the code you show above work, without needing to use require.js directly?

[stsje]

Yes the above code does work. Will have to investigate futher if there are any race conditions though.
Also you don't have the option to use the environment variables in the configuration which makes it kind of a less ideal solution.

[EisenbergEffect]

Good point.

[AshleyGrant]

I just had an idea of how to fix this. I'm going to submit a PR for it momentarily