13 Apr
2005
13 Apr
'05
7:33 p.m.
It would be great to have a method
MAElementDescription >>
attributeAt:put:
to specify new attributes for the component of a description.
Currently,
one
has to use #attributes which is not convenient.
Margritte is not a Seaside framework, generally speaking.
As far as I know there is just one use of #attributes: in SmallWiki
itself
and as I don't write code that I don't need, I didn't felt the need
for
such methods yet. However feel free to add them for your convenience,
that's the reason why there are class extensions ;-) Or how do you see the future of Magritte? I think it
has a great
potential and the possibility to customize the components easily
without subclassing might come in quite handy.
As I mentioned in the presentation, we are using Magritte in industrial
environment as well, where the users are able to click together
web-forms on their own and specify arbitrary complex validation rules.
Another issue currently is the customization of a
description if it
depends
on the instance of the structure. For instance, one would like to have
elements in a select list that are dependent on the instance of a
structure
and that cannot be determined statically. As far as I understand the
only
possibility to achieve that is to override #description on the
instance-side and to add the desired instance-dependent elements
there. Or
am I mistaken here?
Yes, you are! You can do it on the class side using the
description-builder as well. Imagine a hierarchy where A is the
superclass of B and B is the superclass of C:
A class>>descriptionFoo
^(MAOptionsDescrion key: #foo)
options: self optionsToBeUsed;
yourself.
A class>>optionsToBeUsed
^#( a b c )
B class>>optionsToBeUsed
^super optionsToBeUsed , #( 1 2 )
A will have description with #( a b c ), whereas B will have one with
#( a b c 1 2 ).
Another powerful thing is the MADynamicObject class, that allows to
define descriptions where you don't know the possible properties in
advance. Try something like:
B class>>optionsToBeUsed
^MADynamicObject on: [ 1 to: 100 atRandom ].
It is also possible to clear a description element in a subclass, by
overriding the description method and returning nil
C class>>descriptionFoo
^nil
or you could change the description of the superclass by modifying it:
C class>>descriptionFoo
^super descriptionFoo
beReadonly;
nilLabel: 'nothing';
yourself.
Och, I like objects so much ;-)
Cheers,
Lukas
--
Lukas Renggli
http://www.lukas-renggli.ch