[dev-context] Error handling in modules?

[Taco Hoekwater]

Brooks Moses wrote:
> Hi!
> 
> In LaTeX, there is a \PackageError macro for reporting errors from 
> packages -- basically, it's just a standard way of creating a TeX-like 
> error message, with a user-defined text, and the standard "?" prompt 
> waiting for user intervention.
> 
> Is there a similarly standard way for producing error messages in 
> ConTeXt modules?

The normal approach in ConTeXt is to use the messaging system for a
nice looking warning, then call the \wait macro if the user's immediate
attention is really, really needed. No calls on \errmessage and \errhelp
are made except in third-party bits.

I used to do stuf like this:

\startmessages all
    library: brooks
    title: brooks
    1: -- (warning)
    2: -- ! (error)
    3: -- ! (fatal)
\stopmessages

\def\warning#1{\showmessage{brooks}{1}{#1}}
\def\error#1{\showmessage{brooks}{2}{#1}\wait }
\def\fatal#1{\showmessage{brooks}{3}{#1}\batchmode \wait }


Cheers, Taco