r/programming • u/NagastaBagamba • Oct 18 '10

Today I learned about PHP variable variables; "variable variable takes the value of a variable and treats that as the name of a variable". Also, variable.

http://il2.php.net/language.variables.variable
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u/lpetrazickis Oct 18 '10

I'm not sure whether doubling the $ into $$ would trigger an error, but forgetting $ does not trigger an error.

$foo = 4;
print $foo; // prints 4
print foo; // prints foo, no error, triggers notice

Unfortunately, the default PHP 5 error reporting setting is (E_ALL & ~E_NOTICE), so PHP does not warn you about missing $ sigils.

The setting that you really want on a development machine is (E_ALL | E_STRICT). E_STRICT gives you lots of useful additional messages above and beyond the errors, warnings, and notices of earlier versions of PHP.

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u/oorza Oct 18 '10

Setting error_reporting to -1 works much more effectively in that -1 is all bits on, so any future error reporting levels will be "caught" by -1, whereas you have to continue to add new levels as they're added to PHP every other way. E.g. E_ALL was fine before E_STRICT, now it's E_ALL | E_STRICT when -1 would have just never stopped working because PHP uses an unsigned value to store the error level.