Note that what I actually want here is for promise_class() to live directly
on UserAgent and for start_p to directly do ->promise_class->new rather
than Mojo::Promise->new; this module is essentially a way to try that out.
And, yes, this is providing rope for people to choose a stupid class that
doesn't implement promises correctly, which is arguably fragile (and part
of why I provide ->promise_roles(); it's not strictly necessary but it
makes this kind of mistake less likely, though a badly written role can
screw things up, too..), but, if so, then large parts of Mojolicious are
similarly fragile (e.g., someone could just as easily do
ua->transactor(something that doesn't implement Transactor right) and
likewise lose).
... and since I can't/shouldn't edit UserAgent directly, the next best
thing is to intercept promise creation as early as possible. And as far as
I can tell this implementation is as close as it gets: start_p() creates
the promise, then calls start() but doesn't actually pass the promise
itself (it only shows up in the callback which won't get invoked until
after start_p returns). The reblessing is happening before any possibility
of method calls on the object.
Also, this way, if someone wants to customize Transactor::promisify, the
additional promise behaviours/methods will be available there. Your
solution of returning a fresh promise out of start_p wouldn't allow that.
(yes, I understand start_p could get entirely rewritten, but I'm using an
around() hook which is already asking for trouble on that front; I guess
I'm not clear on why reblessing is such a huge sin on top of that...)
On Wednesday, October 2, 2019 at 8:10:16 AM UTC-7, Joel Berger wrote:
>
> Reblessing the returned object into the class of your choosing seems like
> an incredibly fragile way of doing that. I'd recommend that you could just
> chain the returned promise with one that you create/return.
>
> On Tuesday, October 1, 2019 at 8:21:13 AM UTC-5, Roger Crew wrote:
>>
>> Mojo::UserAgent::Role::PromiseClass now exists on CPAN to play with.
>>
>> Promises returned by get_p can now be automatically blessed into whatever
>> class you want by just specifying it once on the UserAgent
>>
>> $ua = Mojo::UserAgent->new(...)
>> ->with_roles('+PromiseClass')
>> ->promise_roles('+Feature'); # add promise features to UserAgent
>> $ua->get_p(...)->feature(sub{...}); # and they show up on every get_p
>> call
>>
>> as opposed to having to type
>>
>> $ua->get_p(...)->with_roles('+Feature')->feature(sub{...})
>>
>> everywhere.
>>
>
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