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HELP CHAINFROM J. Gibson 1981 R. Barrett, January 1986 chainfrom(<procedure1 | call stack length>, <procedure2>) CHAINFROM takes two arguments. 1. a target procedure to chain to, or a call stack length (e.g. the result of *CALLSTACKLENGTH) implicitly identifying a target procedure. (procedure 1) 2. a procedure to run. (procedure 2) When CHAINFROM is called, the calling stack is unwound to the first argument. From there a CHAIN is made to the second argument, which is always a procedure. When the (if) the second procedure finishes, control unwinds up the calling stack, as normal. The first argument may be either an actual procedure (in which case exiting terminates on reaching a call of the given procedure), or a call stack length as returned by *CALLSTACKLENGTH (in which case exiting terminates when the call stack length is equal or less than the given length). -- RELATED DOCUMENTATION ---------------------------------------------- Other non-standard control structures: HELP *CHAIN, *CHAINTO, *EXITTO, *EXITFROM, *CATCH, *JUMPOUT HELP *CALLER - identifies a single caller at a specified level HELP *INTERRUPT - On POP-11 interrupt procedures HELP *CONTROL - for a summary of control structures in POP-11 REF *PROCEDURE - details of the nature of procedures in POP-11 --- C.all/help/chainfrom ----------------------------------------------- --- Copyright University of Sussex 1987. All rights reserved. ----------