RE: Browser tries to download program -- WEB400

Well, unless someone objects I don't see any reason not to talk about
the conditional sections here.

I also limited the section names to 32 characters, that was for two
reasons, one was that I have what some might call an obsession with
using "even" field lengths, by even I mean 1,2,4,8,16,32,etc. but mostly
I chose 32 because of how I store the sections and variables. I use two
dynamic arrays, one for the sections and one for the variables what each
array element actually contains is a pointer to a data structure
containing the section/variable name and a pointer to the contents of
the section or variable. Actually for the section the pointer is to a
linked list of data structures that point to variable data structures.
This means that when I do a wrtsection I only have to do the one lookup
to find the section, and then I just follow the linked list to output
the contents of the section including any variables in it. 

The conditional sections are defined within an existing section of the
template. An example would be something like this.

/$ReportHeader

<h1>
/?SELECT /%month%/ = 00   //00 is the most recent month
Most Recent Report
/?WHEN /%month%/ = 99   //99 means Year to Date
Year to Date Report for /%year%/
/?WHEN /%month%/ >= 1 AND /%month%/ <=12 
Report for /%month%///%year%/
/?OTHER   // the OTHER conditional section is optional.
Invalid date selected for the Report.
?/
</h1>
$/
/*
I don't remember if the original CGIDEV had the ability to use comments
or not but I have it in mine. I can specify // at the beginning of a
line to comment out that line or I can use /* and */ at the beginning of
the line to comment out multiline sections, these comments are not
output to the browser. I also don't remember if CGIDEV had section ends
but mine does a section will end at either $/ or at the next /$,
anything between $/ and /$ is ignored.
*/

I also allow the conditional sections to be nested, so you could have
something like this
/?SELECT /%somevar%/ = 0
some html
/?WHEN /%somevar%/ = 1
blah blah blah
/?SELECT /%someothervar%/ = A
some conditional html (only displayed if somevar = 1 and
someothervar=A)
?/
yada yada yada
/?OTHER
html displayed if none of the above conditions are met
?/

Each conditional can be compound, so ANDs, ORs, and parentheses can be
used in the conditional statement.

As far as what I use them for, the first example is what I usually use
them for. Where the output is dependant on a variable, but does not
necessarily include the variable. I have also used them for things like
making negative values red and positive values black. Mostly they are
another way to separate the presentation from the business logic, the
CGI program just reads and outputs the data, the template determines how
it looks. They also decrease the number of times you need to modify the
cgi program in order to change how the web page looks.

The only draw back to using the conditional sections is because of how
I implemented them. When I read in a template I parse the template into
the sections and I break the sections into blocks of text separated by
variables, comments, and conditional sections. This means that writing a
section is extremely fast. Unfortunately when I did the conditional
sections I didn't parse them at the beginning. Instead when I get to a
conditional section I parse and evaluate the conditional statement
during the write. This means that if you have a conditional section
surrounding a single cell of a report, and if it has several complex
conditions, it can slow the output process significantly. Someday I want
to update the program so that it parses the conditions into a tree of
linked data structures as they are read in and all I have to do is
follow a series of pointers and evaluate the results. But I haven't had
the time to do it yet.

Joe Lee

>>> cozzi@xxxxxxxxx 10/21/2004 15:49:55 >>>
Yes, that's why I wrote CGILIB with the xTools. It doesn't have the
scaling
limitations that CGIDEV2 had. As long as you stay under 16MB of HTML
being
sent at once, there are no practical limitations. I do limit the
section
names to either 32 or 64 characters (can't remember which it is at the
moment), but you can have as many of them as you want.
I would like to hear more about your "conditional sections" including
what
you use them for, and how you use them. Perhaps offline would be better
if
others aren't interested.
As to your 1993... that's perfect. In my CGI RPG classes, I have a line
that
I often use:  "Many long-time HTML coders, and by long-time, I mean
someone
who started using HTML before 1997... seem to prefer Windows Notepad
as
their HTML editor of choice."  That line usually gets a good laugh, but
as
you have indicated... there's some truth to it.  
-Bob


-----Original Message-----
From: web400-bounces@xxxxxxxxxxxx [mailto:web400-bounces@xxxxxxxxxxxx]
On
Behalf Of Joe Lee
Sent: Thursday, October 21, 2004 5:30 PM
To: web400@xxxxxxxxxxxx 
Subject: RE: [WEB400] Browser tries to download program

Well, I suppose I could be considered experienced. I think I wrote my
first web page in 1993. Though I suppose it might be sort of weird
that
I have never put together my own personal website.

I wouldn't say that there is anything "wrong" with using the
noname/*top sections. The reason that I wouldn't use them is that I
like
the consistency of having every section named. Granted in this case
there would only be one unnamed section, but I still prefer to avoid
using a mix of implied and defined section names. I'm also not sure
that
it would work with my version of CGIDEV. We kept running into problems
with not enough sections or variables being available, so I rewrote it
using dynamically allocated arrays to store  up to 32K sections and
variables, and I don't think I made provisions for the "noname"
section.
I also added several capabilities that weren't available at the time,
this was several years ago, such as loading from the IFS, being able
to
load several templates at once, and "conditional" sections which are
like a select statement and allow you to output portions of your
section
based on the values of your variables. 

Joe Lee