[fpc-devel] Considerations about observer [was: Free Pascal 2.6.2 rc1]

[michael.vancanneyt at wisa.be]

On Wed, 28 Nov 2012, Marco van de Voort wrote:

> In our previous episode, michael.vancanneyt at wisa.be said:
>>> Then Luiz is right on time with his proposal, with the frist release
>>> candidate of the first release that contains this feature. If
>>> production code already uses it, then the production code writers must
>>> have taken a risk for change knowing that this was a not yet released
>>> feature.
>>
>> It's rather the opposite. This code was developed and has been in use since
>> years. I simply integrated the code in the classes unit, making the
>> production code simpler.
>
> Yes, and by doing that  you submit it to public scrutiny, risking other
> opinions.

Sure.

Based on feedback, the interface was already changed slightly, but not in 
a super invasive way as asked here.

>> Apart from that, I don't see the point in changing it to an interface.
>
>> At some point, there must be an object, and at some point, there is a
>> typecast,
>
> You often can't reroot external components, but if they support tcomponent

What does "reroot external components" mean ?

> (and thus Tinterfacedobject), you can add an interface in a child class.

The interfaces are CORBA, so there is no need for TInterfacedObject.

That the interface is CORBA was a conscious decision so reference counting 
and all the overhead associated with it was avoided. As far as I know, this
rules out COM provided interfaces (if this is what you refer to by external
components). That is a tradeoff I find acceptable.

>> I can see the speed argument when notifying, but that can be changed by
>> an internal change, without API changes.
>
> As Paul and Vincent correctly state, from the view of the FPC project, the
> interface is not yet fixed.

Correct.

But I want to see some stronger reasons than the ones given before I change the API.

Like I said:
The one about speed in notifyupdates is not a problem, I'll improve that,
implementation speed is important.

Michael.