scope of constants

sarahk

I'm trying to get an understanding of constants.

I have seen some code where a constant is checked in and if absent then a new value is set using defined.

      if ( !defined( 'SOMEVAR')) define('SOMEVAR', $val);

Now the intent of this code is that SOMEVAR is carried through to all subsequent pages at this site but is not available to other visitors. Is this correct?

trooper

Sarah

A constant is available to all scripts that include the page that include the definition. It makes no distinction who to make it available to - every user who visits that page will get the value of SOMEVAR

HTH

Originally posted by sarahk
I'm trying to get an understanding of constants.

I have seen some code where a constant is checked in and if absent then a new value is set using defined.

eg
      if ( !defined( 'SOMEVAR')) define('SOMEVAR', $val); 
Now the intent of this code is that SOMEVAR is carried through to all subsequent pages at this site but is not available to other visitors. Is this correct? [/B]

sarahk

thanks trooper

what I meant to ask tho' is: if I have 3 visitors, will they all have their own idea of what SOMEVAR is. It's an environment variable, but each visitor has their own "environment" and they don't impact on each other.

also, the visitor goes from page 1 to page 2. Is the environment still the same (constants still exist) or is it clean?

trooper

Sarah

If you define a constant then it will be the same for all visitors (unless you say pull something from a db that is relevant to that user and define the constant to that value).

When the user goes from one page to another page then the constant is still there (hence the name 😃 )

Of course i'm assuming that the page where the constant is defined is included at the top of page 1 and page 2

sarahk

thanks trooper. I think I'll set up some test scripts and check it all out.

Of course i'm assuming that the page where the constant is defined is included at the top of page 1 and page 2

I think we've got a bit muddled between the concept of a script/program and a page. My view is that a page is made of one or more scripts.

Thanks for taking the time to answer.