Re: Document/Example how to create "standalone" markup commands

[Aaron Hill]

On 2018-06-07 07:58, David Kastrup wrote:
> Aaron Hill <address@hidden> writes:
>
> > On 2018-06-07 06:34, Aaron Hill wrote:
> > > Hi David,
> > >
> > > Correct me if I am wrong, but the second definition is ***not***
> > > usable as a
> > > function.  That is, it cannot accept a parameter for customizing the
> > > markup.  Unless `\etc` is something magical that is undocumented, the
> > > resulting `\doubleBox` would have to be a complete idea.
> >
> > (See ***correction*** above.)
> >
> > I hate email sometimes... No ability to edit when you make a dumb
> > typing mistake.  Sorry.
>
> I don't understand what you consider "not a function" though.  It is a
> function with constrained form, but a function nevertheless since it
> takes a text/markup parameter.

There are likely many pedants who would say that functions strictly have 
non-zero arity, but that is neither here nor there.

The snippet you mentioned does not work as-is on 2.19.81, so I was 
curious if there was something new going on with how to define 
functions.  As I originally suspected `\etc` was nothing more than a 
placeholder for other, actual markup, your suggested definition of 
`\doubleBox` ultimately becomes a fixed, parameter-less construct.  That 
is, you could not say `c\doubleBox foo`, which is what Urs was trying to 
achieve.  Is there something potentially unsound about using 
define-event-function to that end?

-- Aaron Hill