[PHP-BUG] Req #69738 [NEW]: Declare immutable variables

From:             ugoren at interwise dot co dot il
Operating system: 
PHP version:      Irrelevant
Package:          PHP Language Specification
Bug Type:         Feature/Change Request
Bug description:Declare immutable variables

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 bug report at https://bugs.php.net/bug.php?id=69738&edit=1
-- 
Try a snapshot (PHP 5.4):   https://bugs.php.net/fix.php?id=69738&r=trysnapshot54
Try a snapshot (PHP 5.5):   https://bugs.php.net/fix.php?id=69738&r=trysnapshot55
Try a snapshot (trunk):     https://bugs.php.net/fix.php?id=69738&r=trysnapshottrunk
Fixed in SVN:               https://bugs.php.net/fix.php?id=69738&r=fixed
Fixed in release:           https://bugs.php.net/fix.php?id=69738&r=alreadyfixed
Need backtrace:             https://bugs.php.net/fix.php?id=69738&r=needtrace
Need Reproduce Script:      https://bugs.php.net/fix.php?id=69738&r=needscript
Try newer version:          https://bugs.php.net/fix.php?id=69738&r=oldversion
Not developer issue:        https://bugs.php.net/fix.php?id=69738&r=support
Expected behavior:          https://bugs.php.net/fix.php?id=69738&r=notwrong
Not enough info:            https://bugs.php.net/fix.php?id=69738&r=notenoughinfo
Submitted twice:            https://bugs.php.net/fix.php?id=69738&r=submittedtwice
register_globals:           https://bugs.php.net/fix.php?id=69738&r=globals
PHP 4 support discontinued: https://bugs.php.net/fix.php?id=69738&r=php4
Daylight Savings:           https://bugs.php.net/fix.php?id=69738&r=dst
IIS Stability:              https://bugs.php.net/fix.php?id=69738&r=isapi
Install GNU Sed:            https://bugs.php.net/fix.php?id=69738&r=gnused
Floating point limitations: https://bugs.php.net/fix.php?id=69738&r=float
No Zend Extensions:         https://bugs.php.net/fix.php?id=69738&r=nozend
MySQL Configuration Error:  https://bugs.php.net/fix.php?id=69738&r=mysqlcfg