Re: [PHP-DEV] Calling symbol table patch From: Sterling Hughes (Sterling.Hughes <email protected>)
Date: 11/20/00

At 10:56 PM 11/20/2000 +0200, Andi Gutmans wrote:
>At 09:44 PM 11/20/00 +0100, Sterling Hughes wrote:
>>At 10:43 PM 11/20/2000 +0200, Zeev Suraski wrote:
>>>At 22:35 20/11/2000, Andrei Zmievski wrote:
>>>>On Mon, 20 Nov 2000, Andi Gutmans wrote:
>>>> > Andrei,
>>>> >
>>>> > The patch slows down the main function call opcode. I really don't
>>>> like that.
>>>>
>>>>How much really does it slow it down? It's just putting a pointer on a
>>>>stack before the actual call and taking it off afterwards.
>>>
>>>Well, a stack push is a considerable slowdown. How much it slows things
>>>down exactly obviously depends on your script...
>>>
>>>> > Is it really that important? When did you bump into this need and why
>>>> > couldn't you handle it with the existing functionality? I'm not
>>>> quite clear
>>>> > as to when in programming you *need* such functionality and can't
>>>> write the
>>>> > code in a different (IMO better) way.
>>>> > But then again, you might have a very good reason because I don't know
>>>> > when/how this need arose.
>>>>
>>>>It's impossible to implement some functionality without some sort of a
>>>>patch like this. For example, I am working on a template engine, and I
>>>>need to assign a variable to the template, and I got sick of typing
>>>>something like this:
>>>>
>>>>$tpl->assign('foo', $foo);
>>>>
>>>>So, I wanted to speed it up and have a method that could take just names
>>>>of the variables and assign them using their current values in the
>>>>calling scope, like this:
>>>>
>>>>$tpl->batch_assign('foo', 'bar', 'color1');
>>>>
>>>>But there is no way to get to calling scope:
>>>>
>>>>class Template {
>>>> function batch_assign() {
>>>> $args = func_get_args();
>>>> foreach ($args as $var_name) {
>>>> /* Right here, we have no idea what $$var_name
>>>> is in the
>>>> * function that called us. */
>>>> }
>>>> }
>>>>}
>>>>
>>>>So, that's why I wanted that patch.
>>>
>>>I think that the Right Way to do it would actually be a function that
>>>returns the current symbol table. Such a function can be implemented
>>>without slowing down or modifying anything in the engine, and then you
>>>could write:
>>>
>>>$tpl->batch_assign('foo', 'bar', 'color1', get_active_symtable())
>>
>>
>>>It's a bit more to type, no doubt, but I think it's more correct that
>>>way... Perhaps one day we'll have macros in PHP :)
>>
>>
>>Uhh, you guys turned down a patch that did just that, it was a
>>preliminary version of the get_defined_vars() function which returns the
>>global symbol table and the current symbol table. I had it so that you
>>could then access and modify the variables returned (since it was merely
>>a reference to the respective symbol tables), but (Andi I believe)
>>requested that I not do this, so as it is it just returns the names of
>>the different variables and not their contents.
>
>Hmm I thought it did so :) I was against making it modifiable but it's OK
>to create a copy and it would solve Andrei's problem. zval_copy_ctor()
>would do.

For the record, I agreed with you that my original implementation was
in-correct, it just seemed odd what Zeev said :)

I'll modify get_defined_vars...

-Sterling 

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