Erik Hatcher wrote:
On Jun 3, 2005, at 4:30 AM, Robert wrote:
Hi,
After working with tapestry a little bit I decided to find a way to
not use abstract classes anymore. They give me too much trouble. I
was hoping you people could give me some insight in the
possibilities to accomplish this.
For pages I read about the possibility to use getProperty/
setProperty to avoid abstract classes. Could anyone elobarate on this?
There really isn't much to elaborate on. You can make your classes
concrete, use <property-specification> (or <property> in Tapestry 4.0
DTD) in the specification files and simply use get/setProperty in
your Java code to work with the values.
The thing that I don't understand is that when I define my own getter or
setter for a property, that I will get into an infinite loop.
For example if I have an address property and implement:
public Address getAddress()
{
return (Address)getProperty("address");
}
What I expected is that the call would lead into the enhanced class with
its own implementation of getAddress.
I forgot if the enhancing was based on the properties specified in the
page specification, or on the abstract methods, or both.
Of course if I name the method getAddressProperty or something then it
works fine.
Also is anyone using just instance variables and using initialize to
reset them?
Doesn't sound to be too much work to do.
I would only recommend using instance variables sparingly just to
minimize the risk of overlooking the initialization/resetting of
them. But you're right, it's not really that much work.
I think that as long as I do all my instances like this, I will get used
to it and won't forget.
Are there any other downsides on it? Like losing some functionality
regarding lifecycle management?
And how would I deal with the parameters of components? How can I
avoid the abstract getters and setters for those?
Parameters of components become properties also, defaulting to the
same name. So you'd deal with them just like you would properties as
above.
And could I use instance variables for those too? Or just use the
set/getProperty?
I found some strange behaviour while trying to use instances in components.
For example I have a component with a value parameter
<parameter name="value" direction="in" required="yes" type="int"/>
The component class contains:
private int value;
public void initialize() {
value = 0;
}
public int getValue() {
return 50;
}
public void setValue(int value) {
this.value = 40;
}
I noticed that initialize is never called. Isn't it needed for the same
reason as pages?
The first time when going to a page with this component, it will enter
both getValue and setValue. But the next times it will enter just setValue.
The value 50 or 40 are actually never displayed on my page. I will only
see the value that was given to the value parameter.
I really would like to know what is happening.
I find Tapestry very confusing :)
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