<> <> <> <<>> DIRECTORY MathExpr USING [EXPR], Rope USING [ROPE], ViewerClasses USING [Viewer]; MathCommunication: CEDAR DEFINITIONS ~ BEGIN EXPR: TYPE ~ MathExpr.EXPR; ROPE: TYPE ~ Rope.ROPE; Viewer: TYPE ~ ViewerClasses.Viewer; Create: PROC[expr: EXPR _ NIL, name: ROPE] RETURNS[Viewer]; <> << containing the expression expr. If expr = NIL, viewer will>> << contain an empty expression "placeholder".>> SetContents: PROC[viewer: Viewer, expr: EXPR]; <> <> << to be expr.>> GetContents: PROC[viewer: Viewer] RETURNS[ROPE]; <> << a format understood by the AlgebraStructures parser.>> END.