I like the alternate idea here, but I'm not sure what advantage it has
over the current situation?
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This line of reasoning revealed a difference between what your verbiage
suggestion from a few days ago suggests and what is true.
With the "guards" it's pretty simple what occurs. If an unset
(accessor) is called, and another unset is called on that property, the
same internal function which handles unset is called. In the 2nd
instance, it see's that the unset is already being guarded and so the
ordinary "unset" functionality is invoked.
Therefore, take a look at this gist: https://gist.github.com/4463107
I will need to update the RFC because your previous summary which I took
verbatim I missed being incorrect. It's really, in my book, a lot
simpler to say that if an accessor is already "in the call chain" then
it will not be called again and "standard property rules" take effect.
This is why a getter can get its value directly. It's also why if that
getter calls some other code which tries to "get" the value, that get
also bypasses the getter (which prevents infinite loops).
-Clint
On 1/5/2013 12:06 PM, Steve Clay wrote:
On 1/3/13 5:43 PM, Stas Malyshev wrote:
The whole problem here is that the only reason why it is a problem is
because of the accessors that have hidden state in guards. If it were
regular variables (and for all the API consumer knows, they are) there
Please ignore this if it's been debated before:
AFAICT C# strictly separates fields ("properties" in PHP) and
properties (a set of accessors that emulate a field).
So the RFC provides 3 features (using C# terms):
1. A property API
2. A built-in storage variable so you don't need a separate field
3. Access to the storage variable as if it were a field of the same name
I think #2 is useful, avoiding the need to make a separate field just
to make properties read-only or type-hinted. However I think the
complexity and confusion we're running into is mostly caused by #3.
I think we might be better served by having another way to access this
storage variable.
What if instead, we have the storage var available as $prop inside all
the accessors? These would be the default implementations:
get { return $prop; }
set($value) { $prop = $value; }
isset { return $prop !== NULL; }
unset { $prop = NULL; }
Pros:
* Makes clear that $prop is regular var access, and that
$this->PropertyName *always* goes through accessors
* Gives isset/unset full access to the storage var, which allows doing
things that can't be done via setter/getter. E.g. you could actually
implement a property being "unset", which would be different from
having it set to NULL.
Cons:
* Allows "evil", like having reads affect the storage var.
* Allows authors to hang themselves with recursive accessor calls, BUT
those mistakes would be apparent from looking at the code.
What functionality possible in the RFC would be lost by this?
Steve Clay
--
-Clint
