Edit report at https://bugs.php.net/bug.php?id=52583&edit=1
ID: 52583
Updated by: ahar...@php.net
Reported by: martin dot leucht at gmail dot com
Summary: Improved casting and hinting, new magic method
__cast()
Status: Open
Type: Feature/Change Request
Package: Class/Object related
Operating System: Irrelevant
PHP Version: Irrelevant
Block user comment: N
Private report: N
New Comment:
Not a dupe: request #46128 covers casting the other way. (That alone is
probably a good argument for changing the proposed magic method name.)
Previous Comments:
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[2012-09-04 14:20:42] qfox at ya dot ru
dup?: https://bugs.php.net/bug.php?id=46128&thanks=6
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[2010-10-19 11:41:50] rayro at gmx dot de
pretty nice, awesome feature!
but i have some recommendations on this:
1) is it true that i cannot cast to a boolean false? what about throwing the
error if no return was made? the user is able to throw some exception or will
simple not return anything to use the default error mechanism...
2) i think there should be 2 additional types of functions covering your 2
solutions by simply change the name. for your case 1 this should be __cast,
whereas 2 could be __hint? the essential difference is that __hint will be
called in the functions arguments and __cast will be called elsewhere?
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[2010-10-03 18:45:29] + at ni-po dot com
@degeberg: Doesn't the RFC cover casting the other way round? I.e. Class ->
Scalar
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[2010-08-11 16:54:01] degeb...@php.net
See: http://wiki.php.net/rfc/class_casting_to_scalar
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[2010-08-11 16:30:02] martin dot leucht at gmail dot com
Description:
------------
Type casting in PHP is currently limited to the builtin types. It would be very
useful (IMO) if one could cast a value/variable to a class. And also type
hinting could be improved by casting instead of type checking only.
I suggest to solve this by introducing a new magic method for classes, called
"__cast()", that accepts the value to cast as parameter.
I see two possible solutions for its functionality:
(1) __cast() replaces the constructor method
This will force the developer to move logics from the constructor into a
separate function/method (which isn't even so bad) or to copy his code (which
is indeed bad). If the function returns with the boolean value "false", the
default error mechanism is started saying something like "cast to XYZ not
allowed".
(2) __cast() acts like a static constructor
The code must return the casted result itself. That means one would implement
some logics to transform the given value to the needed constructor parameters
and create a new instance on his own. To handle an unsupported value the method
would throw an exception or an error. The negative (or let's say curious) thing
about this solution is, that this cast method could also return a value of a
totally different type (see example).
Test script:
---------------
// see patch file
Expected result:
----------------
// working cast
Actual result:
--------------
// parse errors
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Edit this bug report at https://bugs.php.net/bug.php?id=52583&edit=1
