Accessing a variable in a function from the main script

[traq]

That's interesting. It's the & that makes it work like that yes?

Yes.

References in PHP are a means to access the same variable content by different names ...Note that in PHP, variable name and variable content are different, so the same content can have different names.

That's a good use. I had thought you just wanted to ignore the error.

Really? I thought you meant what I was doing was a bad thing to be doing.

Originally, I did think that, but then you explained that you simply want to handle the error yourself, in a different way than PHP does. That's a perfectly appropriate reason to use @.
By and large, @ is simply used to hide errors, which is not a good idea.

[djr33]

I made an oversight. function sqli_connect( $username,$password,$link=null ){ ... should be function sqli_connect( $username,$password,&$link=null ){ .... I'm very sorry for the confusion. That & passes the variable $link by reference: instead of copying the value into the function's scope (as normally happens), it literally points at the same value, so anything you do to $link inside the function happens to $link outside the function as well.

Ah, now that makes sense. I thought I was missing something before. This still isn't something I do often, but it would work. I'd note that I do think this varies by PHP version (even 4 vs. 5 vs. 6, I think they behave differently in subtle ways, but I can't recall for sure).
Can you, as in your example, create a variable at the same time as using it by reference in a function? Or does it need to already exist in the current scope before you do that?

Agreed. The potential to confuse scope - function-within-function (or class) - is the main reason I avoid it.

Definitely. But I don't mind too much when I know I'm explicitly referring to truly global things (like system settings). I never use it to "refer to the thing I was just working with outside the function" because it might be within another non-global scope, true.
[Well, maybe not never-- for a lazy/simple script with only one level of functions or just to try out some code, I might do that. But I avoid it in anything complicated/important.]




Just for convenience, because these threads are related, I'll add a link here in case we want to refer back to both in a while (or for anyone who comes across this in the future):
http://www.dynamicdrive.com/forums/s...ession-be-used

[traq]

Can you, as in your example, create a variable at the same time as using it by reference in a function? Or does it need to already exist in the current scope before you do that?

Yes; works just fine. No errors, warnings, nothing.

Also, this should work everywhere (although I never mess around with PHP 4 anymore). Sometime - early in PHP 5, *I think* - something called "call time pass by reference" was deprecated and stopped working. That's when you use & with the argument (or return value) instead of in the function definition:

some_function( $a ){ return $a; }

$arg = 'value';

// bad! doesn't work
some_function( &$arg );

// bad! doesn't work
$return =& some_function( $arg );

reference_function( &$a ){ return &$a; }

// $arg passed in by reference
reference_function( $arg );

// return value assigned by reference
// this is actually *exactly* the same as doing $return = 'value'; but wastes much more time doing it
$return = reference_function( 'value' ); 

Basically, in recent versions of PHP, you can define functions that accept/return by reference, but you can't force a function to accept/return by reference if it wasn't designed to.

[djr33]

...something called "call time pass by reference" was deprecated and stopped working. That's when you use & with the argument (or return value) instead of in the function definition:
...
Basically, in recent versions of PHP, you can define functions that accept/return by reference, but you can't force a function to accept/return by reference if it wasn't designed to.

Ah, yes. That's exactly what I was thinking of. Ok, so it can't be something you do in the function call, but in the function definition. That means you'll always need to use it like that.