Andi,
I do not see how this is semantically incorrect, or how it is that much
different than allowing default values for pass by reference arguments.
IMO The only useful reason to deny passing a constant/expression in a
function is to provide a warning message. Some of the problems I
outlined in my post can be solved using default values(only using ZE2,
which allows defaults on reference args); however, default values only
solve rightmost optional parameters. i.e. there is no way to do:
function a($arg1, $arg2="blah", $arg3="blah"){}
a(1, ,3)
In respect to not passing by reference, this problem is solved by doing
the following
function magic_function($var1, $var2, $var3) {
// Note just an example - I would usually use func_get_args...
if ($var2 === NULL) {
$var2 = "blah";
}
}
magic_function(1, NULL, 3);
This technique of course will not work with the current semantics of not
allowing constants/expressions to pass by reference.
-Jason
On Wed, 2002-05-29 at 10:26, Andi Gutmans wrote:
> I don't see any reason to allow passing non-variables by reference.
> It is semantically incorrect.
>
> Andi
>
> At 09:40 29/05/2002 +0200, Stig S. Bakken wrote:
> >If this patch doesn't break anything, and it doesn't give us any
> >difficulties with ZE2 or major design issues, I'm +1.
> >
> > - Stig
> >
> >On Tue, 2002-05-28 at 21:12, Jason T. Greene wrote:
> > > Due to this patch being sent during the msession discussion, it has not
> > > been noticed, so I am resending.
> > >
> > >
> > > -Jason
> > > ----
> > >
> >
> > > From: Jason Greene <[EMAIL PROTECTED]>
> > > To: [EMAIL PROTECTED]
> > > Cc: [EMAIL PROTECTED], [EMAIL PROTECTED]
> > > Subject: [PHP-DEV] [PATCH] Allow constants / expressions to be passed
> > by reference
> > > Date: 25 May 2002 02:18:52 -0500
> > >
> > > Problem
> > > -------
> > >
> > > There are some scenarios where a function requires the ability to modify
> > > parameters that may also be optional. Optional parameters work well,
> > > except in the scenario where all of the pass by reference parameters can
> > > be optional. ex the socket_select() function. Since select is
> > > argument-result, all three arrays that are taken as input must be passed
> > > by reference, yet any can be excluded. So for example if you were
> > > calling socket_select with a read socket array, a write socket array,
> > > yet no exception array (quite common), you are currently forced to do
> > > something like the following:
> > >
> > > $wfds = array($sock1, $sock2);
> > > $rfds = array($sock3, $sock4);
> > > $null = NULL;
> > >
> > > socket_select($rfds, $wfds, $null);
> > >
> > >
> > > I have ran into this problem before several times while developing in
> > > user space. (Especially when passing around semi-complex data
> > > structures)
> > >
> > > Proposed Solution
> > > ------------------
> > >
> > > Allow all expressions to be passed by reference. This will allow
> > > something like the following
> > >
> > > function normalize(&$element_tree, &$node_mapping, $max_depth){
> > > //Code
> > > }
> > >
> > > normalize($my_tree, NULL, 25000);
> > >
> > >
> > > Patch
> > > ------
> > >
> > > I have attached a patch against ZE2 that accomplishes this.
> > >
> > >
> > > Thanks,
> > > -Jason
> > >
> > >
> > >
> > >
> > >
> > > ----
> > >
> >
> > > Index: zend_compile.c
> > > ===================================================================
> > > RCS file: /repository/ZendEngine2/zend_compile.c,v
> > > retrieving revision 1.285
> > > diff -u -r1.285 zend_compile.c
> > > --- zend_compile.c 23 Apr 2002 18:06:53 -0000 1.285
> > > +++ zend_compile.c 25 May 2002 06:45:21 -0000
> > > @@ -1271,7 +1271,7 @@
> > > op = ZEND_SEND_REF;
> > > break;
> > > default:
> > > - zend_error(E_COMPILE_ERROR, "Only
> > variables can be passed by reference");
> > > + op = ZEND_SEND_VAR;
> > > break;
> > > }
> > > }
> > > Index: zend_execute.c
> > > ===================================================================
> > > RCS file: /repository/ZendEngine2/zend_execute.c,v
> > > retrieving revision 1.341
> > > diff -u -r1.341 zend_execute.c
> > > --- zend_execute.c 8 May 2002 18:43:19 -0000 1.341
> > > +++ zend_execute.c 25 May 2002 06:45:25 -0000
> > > @@ -2292,10 +2292,6 @@
> > > NEXT_OPCODE();
> > > }
> > > case ZEND_SEND_VAL:
> > > - if
> > (EX(opline)->extended_value==ZEND_DO_FCALL_BY_NAME
> > > - &&
> > ARG_SHOULD_BE_SENT_BY_REF(EX(opline)->op2.u.opline_num, EX(fbc),
> > EX(fbc)->common.arg_types)) {
> > > - zend_error(E_ERROR,
> > "Cannot pass parameter %d by reference", EX(opline)->op2.u.opline_num);
> > > - }
> > > {
> > > zval *valptr;
> > > zval *value;
> > > @@ -2329,7 +2325,8 @@
> > >
> > zend_ptr_stack_push(&EG(argument_stack), varptr);
> > > NEXT_OPCODE();
> > > }
> > > - zend_error(E_ERROR, "Only
> > variables can be passed by reference");
> > > + /* Should only occur with an
> > uninitialized variable */
> > > + goto send_by_var;
> > > }
> > > NEXT_OPCODE();
> > > case ZEND_SEND_VAR:
> > >
> > > ----
> > >
> >
> > > --
> > > PHP Development Mailing List <http://www.php.net/>
> > > To unsubscribe, visit: http://www.php.net/unsub.php
> > > ----
> > >
> >
> > > --
> > > PHP Development Mailing List <http://www.php.net/>
> > > To unsubscribe, visit: http://www.php.net/unsub.php
>
>
> --
> PHP Development Mailing List <http://www.php.net/>
> To unsubscribe, visit: http://www.php.net/unsub.php
>
--
PHP Development Mailing List <http://www.php.net/>
To unsubscribe, visit: http://www.php.net/unsub.php
