Seems to me the transformer has the benefit of telling you what it is
really doing. The compiler could take advantage of that knowledge
(in the future) to be more efficient, e.g., by attaching the
attributes and methods to the class rather than the instance when the
parent is a class.
A transformer really is a mixin. I like this path, because it means
that we are continuing to reinvent Lisp :) (c.f., http://
www-128.ibm.com/developerworks/java/library/j-diag1203/). I can pass
on a copy of the JAM paper from TOPLAS if you are interested.
On 20 Dec 2005, at 18:02, Jim Grandy wrote:
Sorry, I actually missed your use of transformer. I was thinking of
something even simpler:
<class name="mouseattachment" extends="node">
<method event="oninit">
this.parent.mouseisin = false;
this.moverdel = new LzDelegate( this, "onmouseover", parent,
"onmouseover" );
this.moutdel = new LzDelegate( this, "onmouseout", parent,
"onmouseout" );
</method>
<method name="onmouseover">
this.parent.mouseisin = true;
</method>
<method name="onmouseout">
this.parent.mouseisin = false;
</method>
</class>
(I guess I could just answer my own question by trying this code
out. I'll do that if I get time tonight.)
jim
On Dec 20, 2005, at 2:44 PM, Jim Grandy wrote:
On Dec 20, 2005, at 1:48 PM, Adam Wolff wrote:
Anyway on Dec 20, Jim Grandy wrote:
[snip]
I've seen code in various places in the LFC and components that
creates
event handlers with reference attributes to hook into events in
a parent
view. Granted it is manual, not automatic like states, but
couldn't this
technique be used to build attachment classes that simply
register for
events at initialization?
[snip]
So are you proposing a transformer class (not like an LFC
transformer)
which tends to be used as a singleton and which takes LzNode
instances and
tinkers with them? e.g.
<transformer name="trMouseView">
<method name="transform" args="v">
v.addAttribute( "mouseisin" , false );
v.bindEventHandler( "onmouseover" ,
this.setMouseIsInTrue );
...
</method>
<method name="setMouseIsInTrue">
this.setAttribute( "mouseisin" , true );
</method>
...
</transformer>
A
Yes. Wouldn't this work? How does this require namespaces, five
bug fixes, or a change to the inheritance hierarchy?
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