4.2 Changing behaviors of macros

To rename the existing macro names, use \rename

\rename{name}{new-name}

which defines a new macro whose name is new-name, and set the macro name to void.

Each macro has a stack space to hold some different definitions. It is possible to redefine a macro temporarily, reverting to the previous definition at a later time. This is done with the builtins \pushdef and \popdef:

\pushdef{name}{parameters}{expansion} \popdef{name}

These macros work in a stack-like fashion. A macro is temporarily redefined with \pushdef, which replaces an existing definition of name, while saving the previous definition, before the new one is installed. If there is no previous definition, \pushdef behaves exactly like \define. As a matter of fact, \define is simply an alias to \pushdef.

If you want to disable a macro temporarily, you can use \pushdef and \popdef in combination:

\define\nop{}{} => \pushdef\foo{}{\nop} => \foo => \popdef\foo => \foo =>Hello world.