From:	Rob Nicholson	Date:	Tue Feb  5 04:40:15 2008
Subject:	Re: Lang.Net Symposium 2008

Hello all,

I've been reading the posts to this mailing list with considerable 
interest. Wez's post today w.r.t a new implementation on DLR prompts me to 
wonder about the extension interface. 

I have to declare an interest. I am working on an implementation of PHP 
which runs on a JVM. Like Phalanger, we wanted to make use of  existing 
PHP extensions so we were faced with the problem of attaching these 
extensions to a managed runtime. We found that  the interface between the 
extensions and the engine is quite a wide one. In many cases extensions 
read and write to the engine internal structures. It occurred to me that 
it might be valuable to attempt to define a narrower, more abstract 
extension interface. 

If this were possible, then it would allow looser coupling between 
extensions and the engine, allowing more scope for ZE2 optimization 
without breaking extensions.  It should also make the extension interface 
simpler, more consistent and easier to use correctly. This would lead to 
more extensions of higher quality and less breakage from release to 
release. It would also allow extensions to be easily used with multiple 
PHP runtimes without dragging in large parts of ZE2. 

To be successful in this endeavour would clearly require  buy-in from the 
PHP internals community but seems to me that in the long run, the PHP 
community at large benefit from there being multiple PHP runtimes. Having 
multiple implementations can only broaden the applicability of PHP still 
further. Other scripting languages already have first rate JVM and CLR 
implementations which are embraced by relevant the language community.

It seems likely that multiple implementations can be  used to cross check 
each other, and indeed I have already seen this happening at php.net.  I 
know that the phalanger team found and reported many bugzillas to php.net 
and we have been trying to do the same. There are lots of opportunities 
for sharing tests too.

I'd be interested to hear from anyone who would like to  take this idea 
further or indeed has any opinion on this matter. 

Rob Nicholson.






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