PHP Constant Does Not Exist: Notification

Question

I would like to use constants as configuration variables in my PHP applications only when the constant does not exist (for some reason) it throws me a notification, but I would like it to be an error (or exception), just like when I try to repeat a non existing variable.

This is possible without using a separate function to get constant values, something like this:

echo $non_existing_variable; // Error
echo NON_EXISTING_CONSTANT; // Now also an error

I searched a little, but could not find anything.

It seems logical to me when I try to use a variable that does not exist, the execution of the code immediately terminates and throws an error, why is this not the case with constants?

Answer 1

defined , -

if (defined('CONSTANT')) {
    echo CONSTANT;
} else {
    throw new Exception('Undefined Constant.');
}

Edit:

, , , set_error_handler, .

Answer 2

,

• ,
• , < Undefined class constant '
• ,

, . , . PHP .

class Config{
    const CONFIG_ONE = 42;
}
//will produce a fatal error 
if(Config::CONFIG_TWO){
   //...
}

, . , hijinks (. set_error_handler).

, , , - singleton private class, . , , - undefined, .

Answer 3

. :

http://php.net/manual/en/errorfunc.examples.php

http://www.w3schools.com/php/php_error.asp

Answer 4

, ( ) . , .

: handling-errors-as-exceptions-best-methods

Answer 5

defined , , .

Answer 6

, , , , - php- , .

It seems kind of logical for me when I try to use a variable that does not exist. Code execution is executed immediately and throws an error, why is this not the case with constants?

Thanks, bye (-: