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: You know, the # sign could be replaced with @ or any other character Previous Comments: ------------------------------------------------------------------------ [2015-06-02 14:42:00] rasmus@php.net And break millions of lines of code out there that use # comments? No chance. ------------------------------------------------------------------------ [2015-06-02 06:51:50] ugoren at interwise dot co dot il I was able to implement this feature myself: http://stackoverflow.com/questions/30570763/replace-the-in-php-variable-declaration/30588938#30588938 I would love to see this feature implemented (and extended) in PHP7 ------------------------------------------------------------------------ [2015-06-01 12:45:58] cmb@php.net At first it should be noted that this syntax (# instead of $) is not possible, because # starts a line comment (it's an alternative to //). | #a=array(1,2); | #a=array(1,3);//ok | #a[1]=4;//error: modifying immutable variable If the second statement is allowed, I wouldn't say that the variable is immutable, but rather that the value is immutable. It is, however, already possible to have immutable values by using immutable objects. ------------------------------------------------------------------------ [2015-06-01 11:13:54] chx@php.net The language specification describes the language as it is. This is a feature request against the language itself. ------------------------------------------------------------------------ [2015-06-01 11:06:02] ugoren at interwise dot co dot il Description: ------------ I would like to have an option to declare immutable variables, for example $a=1;// is a mutable variable #b=1;// is an immutable variable The advantages of immutable variables are numerous: 1. caching function return values 2. parallelism (no shared memory) 3. pass variables by reference 4. Testability, just record a pure function's input and outputs, and you have automatically generated unit-tests. Test script: --------------- //sample code: #a=array(1,2); #a=array(1,3);//ok #a[1]=4;//error: modifying immutable variable //pure functions: function #pure_function(#a,#b) { return #a+#b; } ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=69738&edit=1