using group

control structure

using group ((group-name (&group-name)*)|#implied)


The groups used by a rule or action can be changed "temporarily" by the using group prefix. The new groups are only in effect during the action that follows. After the action ends, the previous groups are returned to active status.

If the active set of groups is changed by next group is while within an action prefixed by using group, the groups activated by the next group is action are only effective until the end of the action prefixed by using group.

This example illustrates the use of the using group prefix with the submit action. This use allows a programmer to apply a different set of find rules to the submitted text than those find rules which are currently being used at this point in the program:

  find "\table{" [ \ "}"]+ => file-name "}"
    using group table-processing
      submit file file-name

The #implied group cannot be combined with other groups in using group prefixes, because it would have no effect. The rules in the #implied group are always active, whether or not they are mentioned. using group #implied is a way of deactivating all of the programmer-defined groups in the program.

The following syntactic variations are permitted:

  • The keyword and can be used to replace "&".
  • The list of group-names can be placed in parentheses to improve readability.

Related Syntax
Related Concepts