Re: [Gnash-dev] Static Members

[Michael Carlson]

Ah, this is really helpful, and although I need to digest some of the
concepts you talked about a little further, I think that is the right
idea for case 2 of the 2 original cases I gave. As far case 1 - say
calling, for example, Date.UTC() - Do you have a solution for this?

The way I understand it, when gnash is asked to find "Date.UTC", it's
going to get the Date object (which currently is an as_value of type
function - the constructor for the Date object, which is defined in
date_new in Date.cpp), and try to get a member of this object called
"UTC" (which it won't be able to find, because the constructor is an
as_value which is not derived from as_object and has no child
members).

- Mike

On 3/12/06, strk <address@hidden> wrote:
> Hello Mike, nice to hear you're working on this.
> I'm not sure I understand your questions, anyway they look
> like something I worked on already for Function.cpp.
>
> Basically we need to model ActionScript inheritance as
> a whole.
>
> I started with assumption from AS1, which are as follows:
>
>  1. Every function has a 'prototype' member which
>     contains 'exported' (virtual, I'd say) members.
>
>  2. Every object has a __proto__ member pointing
>     to it's constructor's 'prototype' member.
>
>  3. The 'prototype' member of a function has a 'constructor'
>     element pointing to the function itself.
>
> Following this, I made as_object::get_member always look,
> recuring, into the __proto__ element when a member is not
> found locally.
>
> To make a simple example, consider the Object class.
> In Gnash this is currently NOT a class, but somtething hard-coded.
> It it has to be a class it would ba an as_function_object
> member of the s_global (Actionscript's _global) object and
> named 'Object'.
>
> When following actionscript code is found:
>
>         var a = new Object();
>
> The variable 'a' would be constructed by the s_global['Object']
> as_function_object, which would be Object class' constructor.
>
> a['__proto__'] would then point to s_global['Object']['prototype']
>
> When calling a.toString() ( current handling being hard-coded)
> Gnash should look at a['toString'], when not finding it (this
> is already implented in as_object::get_member) it will look
> into a['__proto__']['toString'] and will find it.
> The found member would really be Object.toString().
>
> The code I used for Function is not surely the best one, but
> works fine as far as I tested it.
>
> The point is to be able to do, in actionscript, something like
> this:
>
>         var d = new Date();
>         Date.prototype.sayHello = function() { trace("Hello"); }
>         d.sayHello();
>
> This is *known* to be expected to work, and it is commonly used
> with the MovieClip class, adding functions to the drawing API.
>
> I'm interested in discussing this further, and please let
> me know if I completely missed your point :)
>
> --strk;
>
> On Sun, Mar 12, 2006 at 02:50:33AM +0800, Michael Carlson wrote:
> > Hey Everyone,
> >
> > I'm going through and implementing some of the basic actionscript
> > classes, and ran into a problem - I don't know how to create static
> > members with the current code.
> > The first idea to come to my head was
> > to add static members to the constructor object itself (to cover case
> > 1 below), as well as adding the member to each instance of the class
> > when created (in the normal non-static way) using the constructor (to
> > cover case 2 below).
> >
> > For reference, examples of the two basic cases (that I can think of)
> > using Date's UTC function (which is static):
> >
> > case 1) Date.UTC(params);
> > case 2) var x = new Date(); x.UTC(params);
> >
> > However, if the static member is a variable which is non-constant
> > (which fortunately none I've encountered so far are - maybe none are -
> > but can the user define a variable like this that is?), this would
> > cause problems as each instance of the class would have its own
> > separate version of the variable. Furthermore, at the moment the
> > constructors are all created as an as_value (of type function), which
> > seems to be unable to have arbitrarily named "members" like objects do
> > anyways.
> >
> > Should we add a new as_value type of "constructor", which has the
> > ability to hold named members like normal objects? Or should we make
> > the constructor and the uninstantiated object definition separate
> > entities in code, in which the static variables would exist in the
> > uninstantiated object definition (this seems to solve all the problems
> > I thought of, but it might be overkill and overcomplicate the code)?
> >
> > What is the proper solution here?
> >
> > - Mike
> >
> >
> > _______________________________________________
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> > http://lists.gnu.org/mailman/listinfo/gnash-dev
>
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