Req #69738 [Opn]: Declare immutable variables

Edit report at https://bugs.php.net/bug.php?id=69738&edit=1 ID: 69738 User updated by: ugoren at interwise dot co dot il Reported by: ugoren at interwise dot co dot il Summary: Declare immutable variables Status: Open Type: Feature/Change Request Package: Variables related PHP Version: Irrelevant Block user comment: N Private report: N New Comment: Regarding your question, the snippet you wrote should yield a syntax error on this line: $b = &#a;//syntax error: Cannot reference immutable objects And just to elaborate more on the immutable variables vs immutable values concepts: 1. An immutable variable (#) cannot be assigned a mutable value. 2. And when assigning a mutable variable ($) the value of an immutable variable, the value would be copied (and not referenced) Previous Comments: ------------------------------------------------------------------------ [2015-06-04 01:32:07] cmb@php.net Well, let's pretend the # syntax is no problem. But what about the semantics of the "immutable variables"? Consider: <?php #a = [1,2]; $b = &#a; $b[0] = 3; var_dump(#a); var_dump($b); ?> What would be the result? ------------------------------------------------------------------------ [2015-06-03 05:25:20] ugoren at interwise dot co dot il First of all, despite the fact that @ is used to suppress errors and warning, it could be used (because variables are tokenized before the error-suppression character) Second, it doesn't really matter... there are a lot of other characters that can be used to declare new variables: ~ , !, %, * , ^ And even, a combination of characters, for example ** It's a very common syntax in other languages. for example, in python: def func (**kwargs): and it is clear that the * in this context does not imply multiplication ------------------------------------------------------------------------ [2015-06-02 15:01:31] rasmus@php.net Like which character? When you look through the parser you will find that there are very few single-character operators available. @ is the error-suppression character. ------------------------------------------------------------------------ [2015-06-02 14:45:04] ugoren at interwise dot co dot il You know, the # sign could be replaced with @ or any other character ------------------------------------------------------------------------ [2015-06-02 14:42:00] rasmus@php.net And break millions of lines of code out there that use # comments? No chance. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=69738 -- Edit this bug report at https://bugs.php.net/bug.php?id=69738&edit=1