>>>>> "Enrico" == Enrico Forestieri <[EMAIL PROTECTED]> writes:
Enrico> Now, when \csname is used to define a command for the first
Enrico> time, this command is made equivalent to \relax until it is
Enrico> redefined.
Ahh, I did not know that \csname...\endcsname could define the macro
if it did not exist...
Enrico> For example, one could define such a thing:
Enrico> \def\ifundefined#1{\expandafter\ifx\csname#1\endcsname\relax}
Enrico> to do something like \ifundefined{foo}...\else...\fi (This is
Enrico> exercise 7.7 in the TeXbook).
But in this case \ifundefined is non-const (in the c++ sense), isn't it?
Enrico> Moral is that you have to define \endXXX only if you have to
Enrico> actually do something when the environment XXX ends.
OK.
JMarc
