like ive said before, instead of writing all this philosophical stuff you
could just implement it and give us a patch, or add an rfe. what is in
wicket now, terminology and semantics, is the first of its kind (like you
said), so perhaps we didnt get it exactly right. but it works for us now.
you are asking for something totally new, but right now we are busy fixing
bugs to get 1.3.0 shipped out of the door. we will be glad to point you in
the right direction and help you along if you choose to do it.
-igor
On 5/20/07, Chris Colman <[EMAIL PROTECTED]> wrote:
> This extend > child thing really didn't seem to be intuitive at all.
> However, once I completely removed it things became more clear.
>
> 1) It has no id tag.. So w/o asking or rtfm you're not going to know
> what's going on
> 2) Wouldn't naming the hierarchy parent > child be more logical? In
> english.. extend + child have no relation...
I suppose it's a philosophical question on a number of levels. The first
level is whether inheritance is a parent/child relationship - I mean no
offence to anyone reading this but, clearly, inheritance is not a
parent/child relationship. To confuse parent/child with
superclass/subclass (or base class/derived class in the more accurate
but old fashion terminology) is a mistake. Subclasses are not children
of their superclass.
If I have a Vehicle class and extend that to make MotorCycle and
Automobile classes then these subclasses are not 'children' of the
vehicle class. They 'extend' vehicle but they are not 'owned by it' or
'born from it'. Parent/child is not an inheritance relationship - it's
an association relationship. Anyone who uses the world 'child' in an
inheritance context probably skipped the first lecture of their OO 1.0.1
course and stayed at the bar.
So let's pretend to ignore that word 'child' is used in this way in
wicket and move to the next philosophical issue: Is the extent/child tag
'the' inheritance relationship or is it just the mechanism that allows
us to take advantage of inheritance in the markup domain (for the first
time in any framework I've seen - which is why I like wicket so much)
and allows a derived class' markup to provide markup to fill a gap
specified in the base class' markup. I believe that in wicket the
'extend/child' tag is the latter.
It's really just like a virtual method in a class definition. You're
declaring some aspect within the base class for which no implementation
is provided in that base class but which must be provided in some class
that extends that base class. We do this all the time in OO - and we are
allowed to provide multiple instances of these in any class, not just
one instance per class, and we therefore give each instance a different
name. The implementation is provided in a subclass by a method that has
a matching name. This is how true and more powerful markup inheritance
could work in wicket. Naming would only be necessary in situations where
more than one markup chuck needs to be 'overridden' or provided in a
subclass.
Sure some of this could be done by creating extra Panel components but
sometimes I just have some markup that is common to only a portion of my
hierarchy. It seems fudgy to have to create new Panel components to
achieve what can be achieved at a markup level quite quickly and easily
and with less code and less classes.
> 3) Instead of relying on the idea of child tags.. Just add more panels
> or other components that fit your need. You have to break out of the
OO
> mindset a bit, but there's a lot of potential once you think outside
the
> bun.
I've aborted the adoption of all other Java UI frameworks I've ever
found because they forced me to break out of the OO mindset. I came to
wicket, and I'm guessing many other OOers have also because it, more
than any other UI framework, let's me keep my OO mindset that has been
the source of all my successes and the production of robust, high
quality, maintainable solutions for my clients over the last 15 years.
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