[pubcookie-dev] login CGI templates

[Jim Fox]

We have a c library that works much like the php FastTemplate
package.  It would also do this template clenaup quite well.
We use it on quite a few other pages at UW.

Take a look.

   http://staff.washington.edu/fox/webtpl/


Jim



On Tue, 14 Jun 2005, Steve Losen wrote:

> Date: Tue, 14 Jun 2005 10:44:22 -0400
> From: Steve Losen <scl at sasha.acc.virginia.edu>
> To: pubcookie-dev at u.washington.edu
> Subject: [pubcookie-dev] login CGI templates
> 
>
> I would like to suggest an enhancement for a future major release of
> pubcookie.
>
> I'm sure we all agree that the login cgi templates for the
> login page, pinit response, status, etc., are rather clunky.
> I think that with a little work, we could clean this up a lot.
>
> In the login_templates directory we could coalesce lots of little
> html "shreds" into just a few template files that are more
> flexible and easier to maintain.
>
> I did a project in perl a while back that used the HTML::Template
> module.  Perhaps we could implement something similar in C for the
> login CGI.  I would be willing to take a crack at coding it.
>
> For those unfamiliar with HTML::Template, it uses syntax
> like this in its template files:
>
> <TMPL_VAR name="variablename">
>
> This corresponds to the pubcookie %variablename% syntax. In the
> above example the value of variable "variablename" replaces the
> TMPL_VAR tag.
>
> The HTML::Template module also has some simple flow control tags:
>
> <TMPL_IF name="varname">
>  The value of varname is
>  <font color="red"><TMPL_VAR name="varname"></font>
> <TMPL_ELSE>
>  This appears because varname has no value.
> </TMPL_IF>
>
> In the above example, if variable "varname" exists and is not the
> null string, then the text between the TMPL_IF and TMPL_ELSE
> tags is output, otherwise the text between TMPL_ELSE and </TMPL_IF>.
> The else clause is optional.  These can be nested, of course.
>
> You can include other template files with the
> <TMPL_INCLUDE name="filename"> tag.
>
> The perl module also has a TMPL_LOOP tag, for outputting the
> rows of a table or items in a list.  I don't think that pubcookie
> needs this functionality.  Besides, it depends heavily on perl data
> structures.  In perl you pass the loop data as an array of hashes,
> not an easy feat in C.
>
> For our purposes, the variable names and values could be passed as
> a variable length parameter list, like the current template expander,
> or else passed as a "char **argv" style vector.
>
> HTML::Template only lets you test if a variable exists and its value
> is non-null.  I think that pubcookie templates need to also test
> if a variable is equal to a particular string.  I propose this
> optional extension to the TMPL_IF tag:
>
> <TMPL_IF name="varname" value="testvalue">
>
> With this capability we could put all of the error messages into a
> template and print the correct one depending on the value of a variable.
> I also suggest that we add a TMPL_ELSIF tag.  Here is how we could
> clean up error messages:
>
> <TMPL_IF name="error" value="BAD LOGIN">
>
>  You entered an incorrect user name or password.
>  Please try again and get it right this time.
>
> <TMPL_ELSIF name="error" value="COOKIE EXPIRED">
>
>  Your login cookie has expired.
>  Don't you ever exit your browser?
>
> <TMPL_ELSIF name="error" value="FORM EXPIRED">
>
>  You didn't submit the login form quick enough.
>  I haven't got all day, you know.
>
> <TMPL_ELSIF name = "error">
>
>  Oh my, a new pubcookie error.  Too bad I don't
>  know what it means.
>
> <TMPL_ELSE>
>
>    Welcome to the pubcookie login service!
>
> </TMPL_IF>
>
> Here is another useful application.  In some cases we already know
> the username field and do not want the user to be able to change it.
> We want a hidden form field rather than a text field.
>
> <TMPL_IF name="user">
>  <input type="hidden" name="user" value="<TMPL_VAR name="user">">
>  User name: <TMPL_VAR name="user">
> <TMPL_ELSE>
>  User name: <input type="text" name="user" size="20">
> </TMPL_IF>
>
> We could implement custom application login messages much more
> cleanly.  We could pass the appid and appserver to each template
> so that something like the following would be possible:
>
> <TMPL_IF name="appid" value="MySpecialApp">
>  Welcome to the special app.
> <TMPL_ELSE>
>  Welcome to Pubcookie.
> </TMPL_IF>
>
> Or if the custom page needs to be radically different:
>
> <TMPL_IF name="appid" value="MySpecialApp">
>  <TMPL_INCLUDE name="special.tmpl">
> <TMPL_ELSE>
>  <TMPL_INCLUDE name="standard.tmpl">
> </TMPL_IF>
>
> The point is, if we have slightly more intelligent templates and
> we pass more information to them, then we won't need nearly as many
> template files and most, if not all, of the logic can be specified
> in the templates rather than in the CGI code.
>
> We should be able to make these improvements:
>
> o  move all the login_whatever shreds into the login template
>
> o  coalesce the status template, pinit_response1, and pinit_response2
>   into one template, since the pinit response and the status are
>   very similar.
>
> o  coalesce all the logout_whatever shreds into a single logout template
>
> o  Eliminate the current support for custom application messages
>   because the new template package would provide that functionality.
>
> I'm willing to code this if there is any interest.  (Actually, after
> thinking about it some I couldn't resist playing around with it a
> little and I've gotten pretty far along.)
>
> Again, this would be for a future major release.
>
> Steve Losen   scl at virginia.edu    phone: 434-924-0640
>
> University of Virginia               ITC Unix Support
>
>
>
>
>
>
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