[texhax] environment from command

[Philip Taylor (Webmaster, Ret'd)]

Barbara Sánta wrote:
> Hi, an elementary question, but I couldn't find the answer: how could
> I define an environment from a command such that an argument of it be
> inside the environment.
>
> Example:
>
> given the next command:
> \command{fix first argument}{variable second arg}{fix third arg}
>
> Construct the next environment:
> \begin{environment}
>    variable second arg
> \end{environment}

Looking at both this and the more recent messages, I have
to confess that I don't really understand what you are
trying to accomplish.  What are "fix first argument" and
"fix second argument", and if they are fixed, why do they
need to appear at all, and how is the expansion intended
to know which environment is to be used ?

Philip Taylor