Re: WML und Meta-HTML (fwd)

[Denis Barbier <nospam@thanx>]

On Wed, 19 Jan 2000, Tobias Oetiker wrote:

> We have some problems with the <protect> <preserve> tag.

Hi tobias,

> We try to use it when defining containers with meta html ... try the
> following script ... I think it should not work like this ...
> 
> wml -r script
> 
> # ---------- Silly test starts here----------------------------
[...]
> #---THe end
> 
> why does this not return 
> 
> Var title=Perpetuum Mobile

Because Meta-HTML 5.09 does not evaluate attributes when function is called.
When you type
  <foo bar=<get-var bar>>
then %attributes is set to "bar=<get-var bar>". The <preserve> tag
resets the variable, and so "bar=" is printed.

In the ChangeLog, i mentioned i had to hack it to restore previous
behaviour, i.e. attributes are evalled when the function is called, but
obviously this does not work.

Here are some workarounds:
a) do not use identical attribute names (silly advice, no?)
b) do not use attributes like
     title="<get-var title>"
   (this is a little bit more relevant).
#  ---------- beginning of working example
#use wml::std::tags

<define-tag link2>
  <preserve title>
  <set-var %attributes>
  Var title=<get-var title>
  <restore title>
</define-tag>

<define-tag link1>
  <preserve alttitle>
  <set-var %attributes>
  <link2 title="<get-var alttitle>">
  <restore alttitle>
</define-tag>

<define-tag project>
  <preserve title>
  <set-var %attributes>
  <link1 alttitle="<get-var title>">
  <restore title>
</define-tag>

<project title="Perpetuum Mobile">
#  ---------- end of example

c) replace 
     <define-tag link1>
       <preserve title>
       <set-var %attributes>
       Var title=<get-var title>
       <restore title>
     </define-tag>
by
     <define-tag link1>
       <preserve title>
       <set-var %xbody>
       Var title=<get-var title>
       <restore title>
     </define-tag>

As you can see, i do not know exactly how to fix this bug.
This was one of the reasons (lack of documentation on the argument
evaluation process) why i decided to leave Meta-HTML and to write my own
macro processor ; this problem will vanish in next release.

-- 
Denis Barbier
WML Maintainer

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