Marcus Börger wrote:
Hello Dan,Yes, this is possible, but it assumes you always only ever have one child class, which
Currently, I don't see an easy way of accessing the constants of a child
class from a base class.
Use the child's class name:
php -r 'class t{static function f(){echo tt::c;}}class tt extends t{const c="Hello\n";} t::f();'
the base class knows the name of (unlikely). You could figure things out dynamically,
as I provided some example code for, but this would become unwieldy with 10s to
100s of derived classes.
But i guess you want something dynamically as $class::const, right?right.
the next example uses 'self' which doesn't work because self is bound atI believe this is correct behaviour. When instantiating an object the methods, properties,
compile time:
php -r 'class t{function t(){echo self::c;}}class tt extends t{const c= "Hello\n";} $o=new tt;'
So you'd need something like '$this::c' which is impossible right now.
Funny thing is the following which returns NULL what makes absolute no sense
to me. It somehow looks like either the correct constant is used but it is
uninitialized or there is an error missing.
php -r 'class t{function t(){var_dump($this->c);}}class tt extends t{const c= "Hello\n";} $o=new tt;'
etc. of the child class and any and all parents are in essence aggregated together into a
new object (the instance). It would make sense (at least to me) that 'class constants'
should NOT be aggregated together on instantiation. They should be constant only for
their particular class definition and all code provided by that class.
So you could have a const foo = 'bar' in both a parent and child class, and they would
be 2 unique constants only accessable by code inside their class definition (how it works
right now).
I take this position because, from a programmer standpoint, when i type 'const foo',
I would like to believe I'm defining a *constant* name/value pair that could not be
changed at runtime. If constants are aggregated together between all parent/child class
definitions on instantiation, then there could be the potential for conflicts and overriding of
constant values.
But I digress.. I just would like an easy way to get to child constants. Having to use
something like myClass::constant from *inside* an object instance *of* myClass seems
kind of... strange.
I imagine that conversation looking something like this:
Scene: A family instance of a Parent and Child are standing side by side. They talk amongst
themselves for a few moments, and then..
Parent speaks: "Mr. Zend Engine, I need to access a static class constant."
Zend: "OK, Parent, a constant of whom?"
Parent: "A constant of my Child. Do you know where I can find my Child?"
Zend: "Errr.. well.. yeah.. your Child is right there!" *points finger*
Parent: "Hey! There's my Child and he's got the constant! Thanks Zend, you know
*everything*!"
Zend: *scratches head and thinks* "Why didn't he just ask him himself instead of wasting
my time?"
Dan Cox
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