[forms-devel] Making the Effect constructor protected

[Miguel de Icaza]

Hello,

Alex, can you shed some light as to what is the scenario that you wanted to
cover by making the constructor accessible beyond the assembly?

On Wed, May 25, 2016 at 5:45 PM, Jason Smith <jason.smith at xamarin.com>
wrote:

> We cannot move where OnElementPropertyChanged is declared without breaking
> ABI.
>
> My objection is subclassing Effect directly has uses, but we have not
> clearly identified even a reasonable subset of them. Without having even
> the faintest idea of what we are going to use this API for we are about to
> open it up. However by opening it we drive users away from Behaviors which
> are more intended for the use case I assume you are thinking of doing with
> the Effect, which was part of the reason Effect is sealed. The Effect being
> sealed thing is really just a convenient implementation detail working
> around our platform limitations.
>
> On Wed, May 25, 2016 at 2:36 PM, Alex Corrado <corrado at xamarin.com> wrote:
>
>> Hey,
>>
>> Thank you for saving me from writing a spec Miguel :)
>>
>> Jason, to address your concern, we are already allowing people to
>> subclass Effect indirectly, because PlatformEffect subclasses it and we are
>> encouraging people to subclass that. So I don’t think making the Effect
>> constructor public adds any additional constraints on our end.
>>
>> The only (minor) API issue I see is that PlatformEffect declares
>> `OnElementPropertyChanged`, when that should probably be declared in Effect
>> itself. I’m not sure if we could move that without breaking ABI. But Effect
>> also exposes the Element directly, so a subclassor could just subscribe to
>> the property changed event themselves.
>>
>> -Alex
>>
>> On May 25, 2016, at 5:03 PM, Miguel de Icaza <miguel at xamarin.com> wrote:
>>
>> Hello,
>>
>> I think we have enough information on this thread as to what is needed
>> and we should make a decision.
>>
>> Currently the Effect class can not be subclassed.   If we think that
>> there are problems with the current implementation that would prevent us
>> from opening that, let us have a discussion about what are the design
>> problems with Effect, so we can decide what to do about it.
>>
>> MIguel.
>>
>> On Tue, May 24, 2016 at 3:15 PM, Jason Smith <jason.smith at xamarin.com>
>> wrote:
>>
>>> Hi Alex,
>>>
>>> The issue I see with this is we just are not sure that we are ready to
>>> expose the effects API as is publicly. Once it is protected instead of
>>> internal that is forever a type users can inherit. That said, please submit
>>> a spec so we can have a formal discussion/review about it.
>>>
>>> Jason
>>>
>>> On Tue, May 24, 2016 at 12:13 PM, Alex Corrado <corrado at xamarin.com>
>>> wrote:
>>>
>>>> Hello Forms people,
>>>>
>>>> As it stands now, it is impossible to create a cross-platform Effect in
>>>> a PCL. To enable this, I propose we make the Xamarin.Forms.Effect
>>>> constructor `protected` instead of `internal`.
>>>>
>>>> I have already tried it and found it to work great, and I can’t think
>>>> of any way this could break any existing code. I already submitted a PR,
>>>> https://github.com/xamarin/Xamarin.Forms/pull/178 , but was told to
>>>> discuss here first.
>>>>
>>>> Cheers,
>>>> Alex Corrado
>>>>
>>>>
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>>>>
>>>
>>>
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>>>
>>>
>>
>>
>
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