From: arendjr at gmail dot com
Operating system: All
PHP version: 5.1.6
PHP Bug Type: Feature/Change Request
Bug description: Support for lazy evaluation type
Description:
------------
This is a feature request for a special language feature in PHP. I'm not
sure how hard this feature would be to implement, but given the scripting
nature of PHP I can imagine it not being too hard and it would be very
useful if PHP6 could support this.
What I want to ask for is a new variable type that would support lazy
evaluation. I'm not sure what would be a suitable syntax for such a
feature, but let's assume for a moment it would use sqaure brackets.
This feature would allow someone to write code like:
$foo = [1+1];
This statement would basically store the string "1+1" in $foo, and $foo
would be marked as being of type "lazy". Only when at some point the
value of $foo is being read, the code will be evaluated and the real
result will be stored in $foo. So, if someone would subsequently execute
the following statement:
echo $foo;
This would actually expand to:
$foo = eval("return (1+1);");
echo $foo;
This feature would make it very easy to write code that would
conditionally avoid potentially expensive statements.
As an example, imagine a case where you have to call some function bar()
that takes an argument from which you do not know in advance whether the
function will actually use the argument because whether the argument is
used depends on some external factor. However, calculating the argument
may be a very CPU intensive task. In this case you could write:
bar([someVeryExpensiveFunction()]);
Thus avoiding the execution of someVeryExpensiveFunction() in the case
bar() does not actually use its value.
--
Edit bug report at http://bugs.php.net/?id=39280&edit=1
--
Try a CVS snapshot (PHP 4.4):
http://bugs.php.net/fix.php?id=39280&r=trysnapshot44
Try a CVS snapshot (PHP 5.2):
http://bugs.php.net/fix.php?id=39280&r=trysnapshot52
Try a CVS snapshot (PHP 6.0):
http://bugs.php.net/fix.php?id=39280&r=trysnapshot60
Fixed in CVS: http://bugs.php.net/fix.php?id=39280&r=fixedcvs
Fixed in release:
http://bugs.php.net/fix.php?id=39280&r=alreadyfixed
Need backtrace: http://bugs.php.net/fix.php?id=39280&r=needtrace
Need Reproduce Script: http://bugs.php.net/fix.php?id=39280&r=needscript
Try newer version: http://bugs.php.net/fix.php?id=39280&r=oldversion
Not developer issue: http://bugs.php.net/fix.php?id=39280&r=support
Expected behavior: http://bugs.php.net/fix.php?id=39280&r=notwrong
Not enough info:
http://bugs.php.net/fix.php?id=39280&r=notenoughinfo
Submitted twice:
http://bugs.php.net/fix.php?id=39280&r=submittedtwice
register_globals: http://bugs.php.net/fix.php?id=39280&r=globals
PHP 3 support discontinued: http://bugs.php.net/fix.php?id=39280&r=php3
Daylight Savings: http://bugs.php.net/fix.php?id=39280&r=dst
IIS Stability: http://bugs.php.net/fix.php?id=39280&r=isapi
Install GNU Sed: http://bugs.php.net/fix.php?id=39280&r=gnused
Floating point limitations: http://bugs.php.net/fix.php?id=39280&r=float
No Zend Extensions: http://bugs.php.net/fix.php?id=39280&r=nozend
MySQL Configuration Error: http://bugs.php.net/fix.php?id=39280&r=mysqlcfg
