There's one peculiarity of how constants work in PHP which it is useful to note (this is not specific to SWIG though) - if you try to use an undeclared -constant, PHP will emit a notice and then expand the constant to a string -version of the constant's name. Unfortunately it is easy to miss the notice -if you're using PHP in a webserver, as it will probably end up in error.log or -similar. +constant, PHP will emit a warning (or a notice in PHP 7.1 and earlier) and then +expand the constant to a string version of the constant's name. Unfortunately +it is easy to miss the warning message if you're using PHP in a webserver as +it will probably end up in error.log or similar. Apparently this will throw +an Error in a future version of PHP, but until then it's something to be +aware of.
@@ -268,8 +270,7 @@ if(EASY_TO_MISPEL) {
The mis-spelled constant will become the string 'EASY_TO_MISPEL', which is treated as true by the if test, when the value of the intended constant -would be treated as false! Modern versions of PHP will at least issue -a PHP notice by default when this happens. +would be treated as false!