[stringtemplate-interest] sequences and unique numbers

[Sam Barnett-Cormack]

Replying to myself again...

Sam Barnett-Cormack wrote:
> 
> Continuing my habit of replying to myself... I know that, currently, ST 
> formal parameters hide the invoking template's parameters, although the 
> caller can override this with <template(...)>. As I was suggesting 
> expanding the template parameter definition syntax, it might be nice 
> (from a documentation point of view) to specify parameters that *don't* 
> hide the caller's values. In face, one thing that would be nice in the 
> kind of use-cases I can imagine is a variant of default specification 
> that allows you to say "this parameter will have the value it has in the 
> caller, unless it's empty (unset) in the caller, in which case it will 
> have this default".

An example of the template code I find myself writing because I can't do 
this:

<if(extends)>
<classhead()>
<else>
<classhead(extends="ASN1Value")>
<endif>

It'd be much nicer, from my point of view, in my use case, to specify 
that in the definition of classhead() instead. Instead, I have to *not* 
list classhead as a formal parameter, even though it needs to be set for 
the template to work. Now, I could set it this way in the body of 
classhead instead, by setting extends as a formal parameter and doing 
the same logic as above there. Wherever I do it, it's messy.

Is there a distinction between "blank"/"null" and "unset"?

-- 
Sam Barnett-Cormack