[Laszlo-dev] SWF9: Need for with(this)

[P T Withington]

Maybe we just need to think a bit more about how we are going to  
convert the user application into something compilable.

I guess we decided that the user application needs to be a class?  The  
question is, whether the globals in the old app should be instance  
variables, or, should they be class variables?  If LzTestManager were  
a class variable, then it would be 'in scope' without needing  
`with(this)`.

But, I think the real problem here is just that LzTestManager needs to  
be class-ified, rather than trying to simulate the old Object way of  
doing things.  In which case the reference to LzTestManager would just  
need to be replaced with `this`, or, removed altogether if you rely on  
AS3's implicit with this inside methods (which reminds me:  the  
compiler should _not_ insert it's own `with(this)` when generating for  
AS3, and makes me wonder if we should simulate the same in our script  
class methods in addition to LZX methods).

On 2007-12-07, at 12:25 EST, Donald Anderson wrote:

> I'm trying to get lztest-node compiled in SWF9, and I see a compiler  
> error
> coming from the included lztestmanager.lzx:
>
> LzTestManager.assertTrue = function(condition, assertion) {
>    if (!condition)  {
>        var errmsg = "FAIL: assertTrue('" + condition + "') failed"
>                    + (assertion ? ': ' + assertion : '');
> ==>        LzTestManager.failAssertion(errmsg);
>    }
> }
>
> On the indicated line, LzTestManager shows up as undefined.
> I've declared LzTestManager as an instance variable of the
> application class that was created, so the LzTestManager.assertTrue
> reference is not a problem.  The indicated one is a problem because  
> the
> associated block for a function expression does not automatically
> inherit the surrounding scope.
>
> What is needed is a with(this), like:
>
> LzTestManager.assertTrue = function(condition, assertion) {
>  with (this) {
>    if (!condition)  {
>        var errmsg = "FAIL: assertTrue('" + condition + "') failed"
>                    + (assertion ? ': ' + assertion : '');
>        LzTestManager.failAssertion(errmsg);
>    }
>  }
> }
>
> I could do this when we generate code for function expression blocks.
> One concern is that this may be done in a static method or block
> (where there is no 'this').  I think we can detect if we're in a  
> static
> context, so I'm not too worried about that.  The other approach is
> adding with(this) to existing code -- is that out of the question?
> I know there are many of these constructions in our source tree,
> and I'm guessing it would affect user's code, you all know that  
> better than I.
>
> - Don
>
> --
>
> Don Anderson
> Java/C/C++, Berkeley DB, systems consultant
>
> Voice:  617-547-7881
> Email:  dda at ddanderson.com
> WWW:    http://www.ddanderson.com
>