On Wed, 2002-03-13 at 05:19, Geir Magnusson Jr. wrote:
>
> I guess the question is - is there any point to doing this? :) It's not
> clear to me what kind of real performance improvements can be realized by
> compiling, because once the template is intepreted, it's bytecode, right?
The AST is bytecode, but I believe the compiled form of a template would
be different in that the reflection would be removed and if types place
in the context were immutable then I believe the compiler would make
things faster.
> I think the motivation for starting a compiler was when we believed that JSP
> was incredibly fast and Velocity was slow. Since thing, we have proved to
> ourselves many times that Velocity is comparable in performance to JSP,
> which is of course, compiled from generated Java code.
I think velocity is comparable to jakarta implementations of JSP but I'm
not sure there has been many comparisons with other JSP implementations.
I am still willing to bet 10 bucks (american bucks ;-)) that the
compiler would make a significant improvement. But some internal changes
to velocity would be required in order to make this actually work. A
core that stated immutable types in the context which would allow for
real complication with the option to allow mutable types if you wished.
Hashtables are convenient and I know people use them but I think that
allow mutable types in the context actually promotes bad design.
> I would be interested in understanding if there really is potential for
> improvement doing this, or if we are just making things more complex with no
> real benefit.
>
> In the case above, you took what is now basically
>
> for(int j=0; j<numchildren; j++)
> {
> getChild(j).render();
> }
>
> And unwound the loop into the two writes
>
> I am sure there is performance improvement there and it could significant in
> such a trivial case (or other optimal situations), but the question is how
> that improvement scales for real-world templates.
I believe the expansion would be greater than this and the AST wouldn't
be reference at all in the final compiled version of the template.
I am honestly not going to be tackling any sort of compiler until
Turbine is finished so I may never be working on a compiler ;-)
> Geir
>
> --
> Geir Magnusson Jr. [EMAIL PROTECTED]
> System and Software Consulting
> "He who throws mud only loses ground." - Fat Albert
>
>
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jvz.
Jason van Zyl
[EMAIL PROTECTED]
http://tambora.zenplex.org
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