[Perl-widget-developer] thoughts on design

[James G S. <JG...@TA...>]

Here are some thoughts and ideas I've had and played with in 
various forms over the last few months regarding themeing and 
html rendering.  Some things might be useful, some not.

Background:  I am currently working on some PHP code to provide 
an environment in which scripts can be independent from most 
content which, in turn, can be independent of the look of the 
page.  The theme object is called to render anything from form 
input tags to tables.

For a live example, browse https://neo.tamu.edu/xyzzy/ .  This is 
a non-public alpha installation being used for current 
development.  The Directory feature uses the theme object to
render the list of found records in LDAP as well as the actual 
record itself.  You could think of the list as a list widget that 
the theme object provides for the script.

I am currently developing a table rendered in PHP that will 
render using <pre>..</pre> text instead of tables.  This will 
allow for a theme that uses no tables for those browsers that 
have a hard time rendering tables.

In addition to providing some components/widgets for the scripts, 
the theme object also handles the page layout.  At the moment, I 
have enumerated 47 (16 with all edge content intact + 31 with 
some edge component missing) different ways to layout a page with 
central and edge content.  For example, the default look of the 
above development site is as follows:

+---------+
|   Top   |
+---------+
|         |
| Content |
|         |
+---------+
|  Bottom |
+---------+

I don't have the proper data structure initialized for this 
particular layout, but if I did, the user would have the choice 
of having this rendered using frames or tables.  Currently, it 
will only use tables.  This is done without the script or theme's 
knowledge.

http://hex.tamu.edu/test.php has three themes available for 
demostration.  It also shows what the ldap directory object 
returns from a successful lookup (me).

Back to the Present:  I would like to bring as much of this logic 
as possible over into the Perl world.  I think a widget system 
would be a good way to do it.  A theme could possibly be a widget 
factory -- I ask it for a widget that can draw a table, and it 
gives me one.  I don't have to know what the package is or the 
specifics of configuring it, as long as I can give it a set of 
headers and the table contents and it can draw a table for me.

I could give the theme object back a set of widgets and it could 
render the page, allowing for the user to choose frames or no 
frames (for example) without causing drastic problems in the code 
composing the page.  Perhaps this could be done with the template 
idea....

Widgets could still be used outside of the widget factory, but 
the code would need to know which widget it was using.  The 
factory would need to be aware of all the types of widgets being 
used in the site.  It could also handle the burden of doing the 
general configuration of widgets, allowing the scripts to focus 
on the items that make the widget unique/useful in their context.

This could also be done (I think) parallel with other efforts 
such as the Widget::HTML::Template idea (milestone 5).  The two 
might even complement each other.
--
James Smith <JG...@TA...>, 979-862-3725
Texas A&M CIS Operating Systems Group, Unix