On Fri, Mar 17, 2017 at 10:19:02AM -0700, Dave Townsend wrote:
One issue I have just spotted is that Task.jsm uses a JavaScript
implementation of promises under the hood while async/await obviously uses
our native implementation in the JS engine. This may mean the two have
slightly different characteristics. That shouldn't matter for new code
written but may cause problems as we attempt to automatically rewrite older
code and tests make bad assumptions.
With the exception of async stacks, the two have basically the same
characteristics these days. Promise.jsm uses native promises to schedule
its flush loop these days, so the two should behave in the same way.
The only particular issue I've run into is that some test code assumes it
will always have a JS caller on the stack for reporting, which isn't
always the case when called as a native promise resolution handler.
On Thu, Mar 16, 2017 at 3:29 PM, Dave Townsend <dtowns...@mozilla.com>
wrote:
For a long time now we've been writing JS code that waits for promises
using Task.jsm and generator functions. Recently though the JS team added
support for the JS standard way of doing this, async/await:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/
Reference/Statements/async_function
Writing code in standard JS is always better for the web, makes it easier
to onboard new engineers and allows for better support in developer tools.
So I'd like to propose that we switch to the standard way of writing these
functions immediately. New code should use async/await instead of Task.jsm
going forwards.
Florian has some rough plans to automatically rewrite existing usages of
Task.jsm to the standard JS forms so for now don't worry much about going
and submitting patches to fix up existing code. Once that is done we can
remove Task.jsm from the tree.
Does anyone object to any of this?
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