fail to compile. The reason is that the TeX macro language, unlike most programming languages, allows nothing but letters in macro names. There are a number of techniques for defining a macro with a name like\newcommand{\cul8r}{Goodbye!}
\
cul8r
. Unfortunately, none of the techniques is particularly
good:
\
csname
\dots\
endcsname
to define and invoke the
macro:
\expandafter\newcommand\csname cul8r\endcsname{Goodbye!} I said, ``\csname cul8r\endcsname''.
\newcommand{\DefineRemark}[2]{% \expandafter\newcommand\csname rmk-#1\endcsname{#2}% } \newcommand{\Remark}[1]{\csname rmk-#1\endcsname} ... \DefineRemark{cul8r}{Goodbye!} ... \Remark{cul8r}
8
” is a letter:
\catcode`8 = 11 \newcommand{\cul8r}{Goodbye!} I said, ``\cul8r''.
\
cul8r
can be used directly
8
” (such as
numbers or dimensions; so
\
setlength{\
paperwidth
}{8in}
tells us:
! Missing number, treated as zero. <to be read again> 8
\
cul
which must always be followed by
“8r
”:
\def\cul8r{Goodbye!} I said, ``\cul8r''.
\
cul8r
can be used directly
\
cul
is followed by anything other
than “8r
”, with a confusing diagnostic —
\
cul99
produces:
(which would confuse someone who hadn’t even realised there was a definition of! Use of \cul doesn't match its definition. <*> \cul9 9
\
cul
in the document).
\
cul
, if any;
as a result, the technique cannot be used to define both a
\
cul8r
and, say, a \
cul123
macro in the same
document.
@
” within the names of internal macros to hide them
from the user and thereby prevent naming conflicts. To this end,
LaTeX automatically treats “@
” as a letter while
processing classes and packages and as a non-letter while processing
the user’s document. The key to this technique is the separation:
internally a non-letter is used for macro names, and the user doesn’t
see anything of it, while the status remains “frozen” in all the
definitions created within the class or package. See
\
@
and @
in macro names for
more information.
Note that analogous use of technique 3 in this example would give us
which works, but rather defeats the object of the exercise. (\begingroup \catcode`8 = 11 \gdef\cul8r{Goodbye!} \gdef\later{\cul8r} \endgroup I said, ``\later''.
\
later
has the “frozen” catcode for ‘8’, even though the value
has reverted to normal by the time it’s used; note, also, the use of
the primitive command \
gdef
, since \
newcommand
can’t make a
macro that’s available outside the group.)
Recommendation: Either choose another mechanism (such as
\
DefineRemark
above), or choose another name for your macro, one
that contains only ordinary letters. A common approach is to use
roman numerals in place of arabic ones:
which rather spoils the intent of the joke implicit in the example\newcommand{\culVIIIr}{Goodbye!}
\
cul8r
!
This answer was added: 2009-06-03
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=linmacnames