We do sort of have attributes on attributes (or at least certain
built-in modifiers), like $path{'...'} and $when. I was thinking that
potential alternative syntax for Geert's proposal would be:
<class name="container">
<attribute name="mything" value="$childref{'specialthing'}"/>
</class>
<class name="thing"/>
<attribute name="ref" value="specialthing"/>
</class>
<container>
<view>
<view>
<thing/>
</view>
</view>
<container>
I agree with Geert and Neil that this is a common situation. I ran into
it a lot when working on the components for LPS 2.0 (e.g. list and
listitem). I think it would be great if this was addressed in the
platform, rather than just agreeing that it is a nice pattern and
sharing example code via the incubator.
Sarah
On Wed, Oct 25, 2006 at 11:39 PM, Geert Bevin wrote:
Hi Max,
I totally agree with you here, user-definable attribute types would
be very handy. Another idea might be to allow attributes on
attributes :-) That was actually my first urge. If you allow any kind
of attributes, or even just an "options" attributes like on the view
tag, then something like this wouldn't have to rely on naming
conventions.
I'll try to get a blog post written before the weekend and otherwise
it will have to wait a week since I'm finally going on holiday ...
yeay! ;-)
Take care,
Geert
On 26 Oct 2006, at 05:46, Max Carlson wrote:
Hi Geert,
I'm sorry for not responding sooner - I think this would make a
great contribution for the incubator. One thing I'd really like to
see in Laszlo are user-definable attribute types. Without adding
language features, I'm not sure what to do besides rely on
convention/naming like you're doing here. Rather than relying on
attribute name, you could have attributes eligible for injection
contain a certain _type_ of sentinel object and check all attributes
in the class for this value.
An example/blog post would be great! Laszlo needs to borrow more
from AOP and this is a great step in that direction. Let me know if
you've got an updated version/example. Thanks!
Regards,
Max Carlson
OpenLaszlo.org
Geert Bevin wrote:
So, is there any interest in this? It seems that at least several
people do think that there should be some kind of a solution to the
parent.parent.parent approach. Should I just post this code on my
blog with some examples and leave it be or would it be suitable for
the incubator?
On 18 Oct 2006, at 11:46, Geert Bevin wrote:
Hi everyone,
I've been doing a lot of OpenLaszlo work in the past months and
one of the main problems I found was the coupled nature of clearly
independent classes that still rely on each-other for global
functionalities. For example, you might have a control strip with
buttons that operate on views that are displayed in a central
area. Each of these items can be developed as individual classes
that have a well defined set of API methods. A user of these
classes will then compose these classes on a canvas and needs to
wire them up so that they are aware of each other. I found that it
was much easier to rely on the hierarchical nature of an
OpenLaszlo layout and to detect the relationships automatically
instead of having to refer to them specifically. This allows the
code to be maintained much more easily since the relationships
will not break if additional levels are added for layout purposes,
for examples.
I developed a simple reference injection mechanism for this and
attached it as a zip archive to this post. It contains both the
'injmanaged' class and a test case.
Would something like this be a worthwhile contribution to
OpenLaszlo itself?
Can it be improved upon? Currently I rely on a prefix of the
attributes to check if they are illegible for receiving the
injected instances. I'd however much rather have a dedicated
attribute type for this or something else that clearly identifies
this functionality instead of relying on a hackish thing like a
prefix. Any thoughts about that?
Best regards,
Geert
<injmanagement.zip>
--
Geert Bevin
Uwyn "Use what you need" - http://uwyn.com
RIFE Java application framework - http://rifers.org
Music and words - http://gbevin.com
--
Geert Bevin
Uwyn "Use what you need" - http://uwyn.com
RIFE Java application framework - http://rifers.org
Music and words - http://gbevin.com
--
Geert Bevin
Uwyn "Use what you need" - http://uwyn.com
RIFE Java application framework - http://rifers.org
Music and words - http://gbevin.com
