Hey Larry,
Glad you chimed in here on this. I my opinion (author of thingy), they
are separate and distinct from data members. More specifically they
are getter and setter code that is called when the property is accessed.
Using your example:
echo $obj->baz; // executes the code "return $this->baz;"
and
$obj->baz = 4; // executes the code "$this->baz = $value;"
So from the perspective of the user of the class, they are just
"properties" but internal to the class they are implemented with
methods and code.
I think everyone would agree that your #1 is definitely not right,
however I believe there is not consensus on whether or not these *are*
different from properties. To the consumer of the class, they are no
different than properties, to the author of the class they are very
different.
On Saturday, October 27, 2012 9:48:12 PM, Larry Garfield wrote:
On 10/27/2012 09:38 PM, Larry Garfield wrote:
On 10/26/2012 05:37 AM, Clint Priest wrote:
I'm opening up several new threads to get discussion going on the
remaining "being debated" categories referenced in this 1.1 -> 1.2
change spec:
https://wiki.php.net/rfc/propertygetsetsyntax-as-implemented/change-requests
------------------------------------------------------------------------
Some people are in favor of the internal functions being generated
by an accessor declaration should be invisible and non-callable
directly. Others are in favor of leaving them visible and callable.
*Type 1 ( Userland Programmer )**
*
As a userland programmer, someone who cares nothing for "how" php
works, only how their own code works. If they define an accessor
they expect to see an accessor, reflection should reflect that there
are accessors and no other "methods" they did not explicitly define.
If they were to reflect on all of the methods of their class and see
a number of __getHours() they may be confused as to why or where
this function came from. From their perspective, they have defined
an accessor and "how" that accessor works on the inside is of no
importance to them and only seeks to complicate or confuse matters
when they are exposed to these "implementation details" of the php
language its-self. If you tried to set a value such as $obj?abc = 1
through an accessor which could not be set, you would probably want
to see an error like: Warning, cannot set Class?abc, no setter defined.
*Type 2 ( Internals Programmer )**
*
As an internals programmer, you want nothing hidden from you. If an
accessor implements special __getHours() methods to work its magic,
then you want to see them, you want to call them directly if you so
choose. In effect you want nothing hidden from you. In this case you
probably don't even want Reflection to reflect accessors as anything
different than specially formatted and called methods on the class.
This can be understandable because you want all information
available to you. You would probably not be confused if you wrote
$obj?abc = 1 and got back an error like "Fatal Error:
Class->__setAbc() function does not exist.
*Unfortunately 80 to 95% of all people who use PHP are of the first
type.**
*
Revealing these internal matters to them would only leave them
confused, possibly frustrated and likely asking about it to the
internals mailing list to answer (repeatedly).
------------------------------------------------------------------------
Thoughts?
Speaking as a user-land programmer that's been following this thread,
but hasn't been able to jump in yet due to the high volume of
comments...
What's unclear to me is what my mental model should be for this new
syntax. That's important for informing how it should be exposed to me.
1) Should I have a mental model of this being some syntax candy on
top of existing properties? Vis, this is just a short-hand for
bean-style classes? By Bean style, I mean Properties that would be
public but aren't because Public Is Bad(tm), so instead we have
getX()/setX() for every property, so that we can still use the object
like a struct rather than an object but still say we're using methods
even though we've just reimplemented public properties with more
verbose syntax. (Note: Yes, I know that's a rather harsh and
judgmental description. I happen to firmly dislike Bean-style objects.)
2) Should I have a mental model that these fancy-pants properties are
some different third thingie on objects, distinct from traditional
data members and methods?
Right now I'm not sure which mental model I'm supposed to use, and I
get the sense that there's no clear consensus on that question yet.
That, I think, is the key question, and will inform how things like
Reflection should expose data about this new syntax.
For instance, if model 2 is how I'm supposed to be thinking, then I'd
expect I'd need a third reflection object for getting things off of
an object/class, separate from traditional data members and methods.
Then it's consistently a third thingie. If, however, I'm supposed to
think of it as just a short-hand syntax for writing a bean, then I'd
expect it to be presented to me as if I'd hand-written all of the
stuff that this syntax is emulating. Vis, methods show up as
methods, and anything I'd be able to read/write directly without
going through an intermediary method should show up as a property
just as it does now.
Note: I'm speaking here of the mental model of the user, which does
not necessarily have any relationship to the implementation details.
If I'm "supposed" to think of it as a third thingie, it doesn't
matter that it may be implemented internally as syntactic sugar. It
should be presented to me as a third thingie, consistently, with the
engine internal implementation details completely irrelevant. (Which
means they can be changed later if needs be.)
I don't know which mental model is intended, nor which one would be
better, but that is, I believe, the question that should inform the
rest of these discussions.
--Larry Garfield
Addendum: If model 2 (third distinct thingie) is how I'm supposed to
be thinking of them, then perhaps an additional keyword is needed to
help drive that point home. Vis:
class Foo {
// Data member, directly accessible.
public $bar;
// Clearly a different type of thingie than $bar.
public property $baz {
get() { return $this->baz; }
set($value) { $this->baz = $value;}
}
// A method as we know and love them.
public function beep() {}
}
Of course, that should only be used if the mental model is that
they're a distinct thingie. If it's just syntactic sugar (again,
mental model, not implementation), then a new keyword is a bad idea.
--Larry Garfield
--
-Clint
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