--- freem/doc/freem.texi 2025/05/02 15:16:36 1.37 +++ freem/doc/freem.texi 2025/05/02 20:01:12 1.38 @@ -4751,10 +4751,63 @@ The effect of this is that the operation @cindex variables, local @cindex local variables +@section Local Variables Overview + +FreeM @emph{local variables} have the same data structure as global variables, but are scoped to a single FreeM process, and stored in memory. + +Each local comprises three elements: + +@itemize @bullet +@item +An alphabetic name beginning with a letter or a percent sign (@code{%}) +@item +Optionally, one or more comma-delimited subscripts, enclosed in parentheses +@item +A value of up to 255 characters in length +@end itemize + +@node Creating Local Variables +@section Creating Local Variables +@cindex local variables, creating + +To create a local variable, use the @code{SET} command: + +@example +SET MYLOCAL("foo","bar")="this is the data value" +@end example + +@node Removing Local Variables +@section Removing Local Variables +@cindex local variables, removing + +To remove an entire local variable, you can use the @code{KILL} command with the unsubscripted name of the variable: + +@example +KILL MYLOCAL +@end example + +If you only want to remove part of a local variable, i.e., beginning at a certain subscript level, use the @code{KILL} command with a subscripted name: + +@example +KILL MYLOCAL("foo") +@end example + +This will remove only the @code{"foo"} subscript and all of its children. + +If you only want to remove the data value at a specific subscript level, leaving the subscript itself intact, use @code{KVALUE}: + +@example +KVALUE MYLOCAL("foo") +@end example + @node Scoping @chapter Scoping @cindex scoping +By default, FreeM local variables and their values are scoped to the entire process, meaning that any function or subroutine can access and modify their values. This can lead to pernicious bugs. + +M provides the @code{NEW} command to work around these issues. When @code{NEW} is called with a local variable as its argument, FreeM will scope the variable to the process stack frame in which the @code{NEW} command occured. When exiting the stack frame (i.e. with the @code{QUIT} command), FreeM will restore the variable to its value prior to being @code{NEW}ed. + @node Decision Constructs @chapter Decision Constructs @cindex decision constructs