ActiveVarTrace - tcl/tkコードリーディング

概要

トレースがアクティブの時、トレースが削除されたときに必要

ソース

/*
 * When a variable trace is active (i.e. its associated procedure is
 * executing) one of the following structures is linked into a list associated
 * with the variable's interpreter. The information in the structure is needed
 * in order for Tcl to behave reasonably if traces are deleted while traces
 * are active.
 */

typedef struct ActiveVarTrace {
    struct Var *varPtr;		/* Variable that's being traced. */
    struct ActiveVarTrace *nextPtr; 
			/* Next in list of all active variable traces
			 * for the interpreter, or NULL if no more. */
    VarTrace *nextTracePtr;	/* Next trace to check after current trace
				 * procedure returns; if this trace gets
				 * deleted, must update pointer to avoid using
				 * free'd memory. */
} ActiveVarTrace;