KILL Command¶
Material prepared from M Programming Book (Page 78) [WALTERS1997] and GT.M Programmer’s Guide
KILL [:bool] var1[,var2][,(ex1,ex2)]
Description¶
KILL, at its most basic level, deletes variables specified in its arguments.
KILL is optionally used with an exclusive list, or a conditional, or on multiple arguments. Additionally, it may be used with no arguments to delete all local variables.
KILLing an undefined variable has no effect.
Arguments¶
-var1,var2,...
Specifies the local variable(s) to be deleted.
Example:
SET A=1,B=2
KILL A,B
SET C=3
KILL C
*Local variables A and B (and then C) will be deleted, and will return undefined if referenced*
-:bool
An optional true/false expression. If true, the kill command will execute. If false, nothing happens.
Example:
SET A=1,B=1
KILL:A=1 B
KILL:A=2 A
*A=1 evaluates true, so B is deleted. Then, A=2 evaluates false, so A is not deleted*
-ex1,ex2
Optionally, an exclusive list (list of variables in parentheses) can be provided. Those variables in the exclusion list will be preserved, while every other variable is deleted. In the event of a variable appearing in the exclusive list and argument list (ex. KILL (A,B),A), its exclusive property is ignored, and it is KILLed.
Example:
SET A=1,B=2,C=3
KILL (A,B)
*A and B are kept, and the remaining variable C is deleted*