Re: Linear web programming in Mason?

On Wed, 16 Jun 2004, Autrijus Tang wrote:

> Hi.  Does anyone know if there were any attempts or discussion to bring Mason
> toward the "linear web programming model", ala Seaside
> (http://beta4.com/seaside2/) or Borges (http://borges.rubyforge.org/)?
>
> This is so one can write components that resembles sequential programs
> instead of state machines.  A short example follows:
>
> %# Counter.mas:
>     <& /header &>
>     <h1>Current Counter: <% $count %></h1>
>     <&|/button, $m->run_method('Incr') &>++</&>
>     <&|/button, $m->run_method('Decr') &>--</&>
>     <%INIT>
>     my $count = 0;
>     </%INIT>
>     <%METHOD Incr>
>     % $count++;
>     </%METHOD>
>     <%METHOD Decr>
>     % if ($count == 0) {
>     %   # to the user, the next line brings up a new page...
>     %	my $ok = $m->run_comp('Confirm.mas', Text => 'Go negative?');
>     %   # ...after the user clicks "Yes"/"No" we are back here!
>     %   return if !$ok;
>     % }
>     % $count--;
>     </%METHOD>
>
> %# Confirm.mas:
>     <& /header &>
>     <p>Please confirm: <b><% $Text %></b></p>
>     <&|/button, $m->yield(1) &>Yes</&>
>     <&|/button, $m->yield(0) &>No</&>
>     <%ARGS>
>     $Text
>     </%ARGS>
>
> I understand the subtleties involved (serializing Coro::Cont state for
> lexical variables; make continuation-passing-style $m facades; separate
> backtrackable methods with nonbacktrackable ones); I merely wish to
> check if were prior arts or discussions about this in the Mason/Perl
> space, and if this is an obviously insane approach to try with Mason.

I've _thought_ about it a little bit, but that's about it.

However, I was thinking of doing it more like this:

  sub new_user {
      my %input = new_user_data(); # dispatches to Mason which displays a form

      while ( my @errors = check_user_data(%input) ) {
          %input = new_user_data(%input, @errors);
      }

      make_new_user(%input);
      redirect(...);
  }

I don't really like the idea of doing that sort of thing within Mason.  I
thought the whole idea of this was to make web programming (with multiple
requests) look like more like regular apps.


-dave

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