Node: Macro protection, Previous: Recursion, Up: Macro features



Protecting macros against redefinition

Normally an FWEB macro can be redefined at will. The example

     @m PI 3.14159
     @m PI (-3)
     

is permissible, but probably not a good idea. If you want to ensure that a crucial macro definition is never redefined inadvertently, say @m!, as in

     @m! PI 3.14159
     

That is called protecting the macro.

FWEB's built-in functions and macros (beginning with $) are protected by default; see Protection. To override that protection, use the command-line options -Tb (-Tb; for built-in functions) or -Tm (-Tm; for macros).