I like this proposal.
That means that there are now two ways to "skin" an app -
* using CSS
* overwriting named resources
Using overwritten resources will make compile-time skinning more
palatable than the 2-step CSS option we currently have. It'd still be
nice to be able to support assigning of resource file-names in CSS.
(LPP-3477 <http://www.openlaszlo.org/jira/browse/LPP-3477>)
-e
Bret Simister wrote:
I prefer putting the responsibility on the developer creating the
library, rather than on the developer using it.
Hence,
<!-- mylibrary.lzx -->
<library>
<resource name="logo" src="logo.png" replaceable="true" />
</library>
would allow a developer using the library to write the following
<canvas>
<inlcude href="mylibrary.lzx" />
<resource name="logo" src="logo2.png" />
</canvas>
and see no warnings upon compile. This seems the cleanest approach to me.
It lets the library developer be explicit about which resources were
designed
to be replaced.
I am also OK with Henry's suggestion about using a compiler flag to
show warnings
when you need to check for resource conflicts. The nice thing about
that approach is that
it has minimal impact upon the language.
-Bret
On Wed, Aug 29, 2007 at 8:03 AM, Elliot Winard wrote:
I can see something like that working -
<resource name="logo" src="blah.png" force="true" />
If the force attribute is present, it overwrites other declarations
of logo and does *not* emit a warning.
The force attribute could mean both "replaceable" and "suppress
warning".
The warning could suggest that the force attribute be used if the
user intends to overwrite in case of conflict.
Resources in libraries could define the force
<library>
<resource name="logo" src="logo.png" force="true" />
</library>
<library>
<resource name="logo" src="logo2.png" force="true" />
</library>
Hrm. Come to think of it, that feels wrong. Would it be too much of
a change if there are two new attributes for resource - force and
replaceable?
@force would be tell the compiler not to emit a warning if this
resource overwrites another.
@replaceable would tell the compiler not to emit a warning if this
resource is overwritten
If these two attributes aren't present the current behavior remains.
So resources in Webtop libraries would look like this -
<library>
<resource name="logo" src="logo.png" replaceable="true" />
</library>
-e
Sarah Allen wrote:
That is exactly the dilemma. The tension is between a the
frustration of an accidental override and the frustration if you
want to set up your library to allow customizing a resource, where
you have to provide a resource file and library separately and then
the user of the library needs to create a new resource file and
include all your resources except the logo and include the logo.
I suppose there could be some kind of flag that says that I meant to
override this resource, like:
<resource name="logo" src="logo.png" replace="true"/>
I don't know if that would complicate the implementation or the
language folk would consider it weird, but as a user of the language
it would work for me.
Sarah
On Wed, Aug 29, 2007 at 5:01 AM, Elliot Winard wrote:
I don't know about removing the platform warnings.
If I include two libraries that have resources with conflicting
names, I want to know about it. For example - I might include
multiple libraries , each defining a 'logo' resource and expecting
the logo to be sized a certain way -
<include "mailwindow" />
<include "stockwindow" />
I want the compiler to tell me that the stockwindow's logo is
overwriting the mailwindow's logo. Warnings are informative,
non-fatal and should be used to provide this kind of information.
This proposal skirts CSS altogether. If this gets implemented as
proposed then the display of warnings should be configurable at
compile-time. I think it would be confusing to users if resources
(or classes or instances) get clobbered without any warning.
-e
Sarah Allen wrote:
I think this is an excellent proposal. cc'ing laszlo-user to see if
other folks developing in LZX have strong feelings about this ...
On Tue, Aug 28, 2007 at 3:12 PM, Bret Simister wrote:
Currently, in the OpenLaszlo platform, it was decided that declaring a
resource twice within an LZX app
causes a server warning. This was intended to help developers just in
case they accidentally overrode a
resource that had already been declared in another library.
<!-- the following code produces a warning, but still compiles -->
<canvas>
<resource name="logo" src="logo.gif" />
<resource name="logo" src="logo2.gif" />
<!-- view appears with logo2.gif -->
<view resource="logo" />
</canvas>
At this time, I would suggest that the platform remove these
warnings and have
the last resource declaration override all other previous
declarations.
Here is why...
OpenLaszlo now has a CSS implementation. It gives developers an
elegant method
of skinning their applications. This works, currently, by first
declaring a resource
<resource name="someimage_rsc" src="somepath/someimage.jpg" />
and then referring to that resource in a CSS selector
view[name="someview"] {
resource: someimage_rsc;
}
If a developer builds a library ....
myCustomLibrary ( folder )
library.lzx
myresources.lzx ( contains many resource definitions including
'lowerRightCorner_rsc' )
mystyles.css ( contains many selectors including one that
references 'lowerRightCorner_rsc' )
... ( other class and source image files )
where library.lzx includes both myresources.lzx and mystyles.css
Then library can be used with a simple inclusion in the main app.
<canvas>
<include name="myCustomLibrary" />
<!-- instance of a class from myCustomLibrary -->
<mycustomclass />
</canvas>
Let's assume that " mycustomclass " contains a number of resources,
and that you ( as a developer )
only want to change one of those resources . The simplest method to
accomplish this would be ...
<canvas>
<include name="myCustomLibrary" />
<!-- override resource definition "lowerRightCorner_rsc" defined
earlier in myresouces.lzx -->
<resource name="lowerRightCorner"
src="my_new_path/my_lower_right_corner.jpg" />
<!-- instance of mycustomclass that will now display
the new resource based on the unchanged css selector -->
<mycustomclass />
</canvas>
Currently, this code would cause a compiler warning. To avoid these
warnings ( without changing OpenLaszlo ) the resouces.lzx file(s) and
possibly the library .lzx would have to be edited.
If instead, we allow for resource overriding, then ...
1) the original CSS and resource files will remain unchanged
2) The old resource for " lowerRightCorner" would NOT be included in
the app
3) There would be clean separation between external libraries and the
skinning of theses libraries included in an application.
