proc(n)                      Tcl ( )                      proc(n)



     _________________________________________________________________

     NAME
          proc - Create a Tcl procedure

     SYNOPSIS
          proc name args body
     _________________________________________________________________


     DESCRIPTION
          The proc command creates a new  Tcl  procedure  named  name,
          replacing  any  existing command or procedure there may have
          been by that name.  Whenever the new command is invoked, the
          contents  of  body  will be executed by the Tcl interpreter.
          Args specifies the formal arguments to  the  procedure.   It
          consists  of  a list, possibly empty, each of whose elements
          specifies one argument.  Each argument specifier is  also  a
          list  with  either  one  or  two fields.  If there is only a
          single field in the specifier then it is  the  name  of  the
          argument;  if  there  are  two fields, then the first is the
          argument name and the second is its default value.

          When name is invoked a local variable will  be  created  for
          each  of  the  formal  arguments to the procedure; its value
          will be the value of corresponding argument in the  invoking
          command  or  the  argument's  default value.  Arguments with
          default  values  need  not  be  specified  in  a   procedure
          invocation.   However, there must be enough actual arguments
          for all the formal arguments that don't have  defaults,  and
          there  must not be any extra actual arguments.  There is one
          special case to permit procedures with variable  numbers  of
          arguments.   If  the last formal argument has the name args,
          then a  call  to  the  procedure  may  contain  more  actual
          arguments than the procedure has formals.  In this case, all
          of the actual arguments starting at the one  that  would  be
          assigned  to  args  are combined into a list (as if the list
          command had been used); this combined value is  assigned  to
          the local variable args.

          When body is being executed, variable names  normally  refer
          to  local  variables,  which  are created automatically when
          referenced and deleted  when  the  procedure  returns.   One
          local  variable  is  automatically  created  for each of the
          procedure's  arguments.   Global  variables  can   only   be
          accessed  by  invoking  the  global  command  or  the  upvar
          command.

          The proc command returns an empty string.  When a  procedure
          is  invoked,  the  procedure's  return  value  is  the value
          specified in a return command.   If  the  procedure  doesn't
          execute  an  explicit  return,  then its return value is the



     Page 1                                         (printed 11/11/93)






     proc(n)                      Tcl ( )                      proc(n)



          value of the last command executed in the procedure's  body.
          If  an error occurs while executing the procedure body, then
          the procedure-as-a-whole will return that same error.


     KEYWORDS
          argument, procedure
















































     Page 2                                         (printed 11/11/93)