Re: [htmltmpl] extended TMPL_IF / UNLESS syntax

[Mathew R. <mat...@re...>]

> > I often find myself generating template code such as:
> >
> > <TMPL_UNLESS error>
> >     <TMPL_UNLESS print>
> >         <TMPL_IF some_var>
> >             .... do something...
> >         </TMPL_IF>
> >     </TMPL_UNLESS>
> > </TMPL_UNLESS>
>=20
> When I see stuff like that I go into my Perl code and whip up
> something like:
>=20
>   <tmpl_if no_error_and_no_print>
>     ... do something ...
>   </tmpl_if>
>=20
>   <tmpl_if no_error>
>     ... do something else ...
>=20
>   <tmpl_if error>
>     ... do something else entirely ...
>   </tmpl_if>
>=20
> That way the template stays simple and I concentrate the complex logic
> in the Perl code where it belongs.  If possible I try to find a way to
> phrase each condition that doesn't involve boolean logic, which few
> non-programmers fully understand.

Thats ok - except that since 'error' and 'print' are orthogonal concepts =
- the metaphore of not displaying either is really a user-interface =
problem, not an application problem.   As such, to generate the =
'no_error_and_no_print' value, the programmer would need to either:
a) get a set of requirements form the UI guy which states what extra =
variables need to be coded up,
b) automatically generate arbitrary names for each combination of =
template parameters, just in case the UI guy needs them.

In either case, we increase coupling between the UI and the backend =
application code.


> > The equivalent using H::T::E would be:
> >
> > <TMPL_UNLESS EXPR=3D"((defined error) or (defined print)) and ....">
> >     ... do something...
> > </TMPL_UNLESS>
>=20
> You can write that a little simpler:
>=20
>   <TMPL_UNLESS EXPR=3D"((error or print) and ...)">

'error' in scalar context, means something slightly different than =
'defined(error)' - however, you are correct for this rather poor example =
of mine...

>=20
> > both syntax's are reasonably ugly...
>=20
> Beauty is in the eye of the beholder...
>=20
> > What about a syntax like:
> >
> > <TMPL_IF !error,!print,some_var>
>=20
> ...which is proven by the fact that I find this much uglier than
> either of the two alternatives!

touche...

cheers,
Mathew