global variables

Anon

I\'ve seen some arguments about PHP, and PHP vs Perl and sometimes ppl say that PHP is bad because it makes ppl use lots of GLOBAL variables. Why is that bad?

Is usage of Globals bad programming?

P.e. if I need $HTTP_GET_VARS[] inside a function, I need to use a GLOBAL, OR pass it inside a parameter.

Wich is recommend and why?

Anon

PHP doesn't 'make' you use any more globals than any other language. It's just a bit more trouble with PHP to decalre them global than it is in some other languages.

The only bad thing about globals is that you can change a value by accident and not have the value you expect. It can make it more difficult to trace down. The general rule of thumb is that if you can do it with a local varaible, then don't use a global.

As for using $HTTP_GET_VARS as parameter vs global. It depends on what the function does. If the function is specific to your current script, there's no reason not to use it as a global in the function. If it is a general function that could be useful with other scripts, and with other arrays, pass it as a parameter.

Anon

My function is inside an included module.

I include/require that module in the pages that need to use it.
It gets $HTTP_USER_AGENT and returns browser and operating system names.
Should I just use it with

function print_browser(){
GLOBAL $HTTP_USER_AGENT;
[ other code ]
}
or

function print_browser($HTTP_USER_AGENT){
[ other code ]
}

and when calling it, puting the $HTTP_USER_AGENT in the parameter zone?

Whats the best practice?

Anon

If you are not modifying values in a function, and are only returning values, or echoing to the screen, I would pass it as a parameter. (It is normally more useful to return a value from a function, and then echo it to the screen, as opposed to echoing the value form the function itself.)

If it would be useful to be able to use a differnt value or array than you are currently using in the function, then pass it as a parameter.

If the Function is only useful with the HTTP_GET_VARS, then go ahead and make it global.