Re: [Groff] d conditional and autovivification of macros

[Werner LEMBERG]

> When I run the following file in groff, I get the output "tenorsax
> implemented":
>
>   .do tenorsax ext 1
>   .de status
>   .ie d\\$1 \\$1\timplemented
>   .el \\$1\tmissing
>   .br
>   ..
>   .status tenorsax

This is expected behaviour.

> I've been using groff for several years and this behavior is
> unexpected; it appears that groff is autovivifying the tenorsax
> request as some sort of macro because of the do request.  It also
> conflicts with the documentation, which doesn't mention that
> behavior.

It is documented in groff's texinfo manual, section `5.4 Identifiers':

     Unlike many other programming languages, undefined identifiers
  are silently ignored or expanded to nothing.  When `gtroff' finds an
  undefined identifier, it emits a warning, doing the following:

     * If the identifier is a string, macro, or diversion, `gtroff'
       defines it as empty.

     * If the identifier is a number register, `gtroff' defines it
       with a value of 0.

So the main question is why you haven't found this documentation
snippet.  Can you tell me where and what you have searched?  Maybe I
can add some index entries.


   Werner