note 58353 deleted from language.types.string by cmb
| From: | cmb@php.net | Date: | Sun, 04 Aug 2019 09:11:32 +0000 |
| Subject: | note 58353 deleted from language.types.string by cmb | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-211798@lists.php.net to get a copy of this message | ||
Note Submitter: DELETETHIS dot php at dfackrell dot mailshell dot com
----
Just some quick observations on variable interpolation:
Because PHP looks for {? to start a complex variable expression in a double-quoted string, you can
call object methods, but not class methods or unbound functions.
This works:
<?php
class a {
function b() {
return "World";
}
}
$c = new a;
echo "Hello {$c->b()}.\n"
?>
While this does not:
<?php
function b() {
return "World";
}
echo "Hello {b()}\n";
?>
Also, it appears that you can almost without limitation perform other processing within the argument
list, but not outside it. For example:
<?
$true = true;
define("HW", "Hello World");
echo "{$true && HW}";
?>
gives: Parse error: parse error, unexpected T_BOOLEAN_AND, expecting '}' in - on line 3
There may still be some way to kludge the syntax to allow constants and unbound function calls
inside a double-quoted string, but it isn't readily apparent to me at the moment, and I'm
not sure I'd prefer the workaround over breaking out of the string at this point.