Structure and Participants

bbllxfalse bbllyfalse bburxfalse bburyfalse heightfalse widthfalse rheightfalse rwidthfalse p@sbbllxp@sbblly p@sbburxp@sbbury p@sheightp@swidth p@srheightp@srwidth p@sfile p@scost10 sc prologfilefalse postlogfilefalse clipfalse psdopsfiga:=figure=graphics/epgeneral.eps,width=8.5cm setparmspsfiga, @bbfalse @bbllx @bbtrue @bblly @bbtrue @bburx @bbtrue @bbury @bbtrue @bb @stream=p@sfile @bbtrue @eoftrue `%=12

@stream to @in 200=@in @stream @eoffalse bbtest200 @bbmatch@eoffalse@cull200 @eof `%=14 @bb -bb-error

203=p@sbburx 204=p@sbbury 203 by -p@sbbllx 204 by -p@sbblly bbw203 bbh204 @height @width

240=bbw 241=bbh 100=240 100 by 241 101=100 101 by 241 240 by -101 240 by 10 101=240 101 by 241 102=101 102 by 241 240 by -102 240 by 10 102=240 102 by 241 200=p@sheight205=0 201=200 201 by 100 205 by 201 201=200 201 by 10 201 by 101 205 by 201 201=200 201 by 100 201 by 102 205 by 201 result205 p@swidthresult

@width 240=bbh 241=bbw 100=240 100 by 241 101=100 101 by 241 240 by -101 240 by 10 101=240 101 by 241 102=101 102 by 241 240 by -102 240 by 10 102=240 102 by 241 200=p@swidth205=0 201=200 201 by 100 205 by 201 201=200 201 by 10 201 by 101 205 by 201 201=200 201 by 100 201 by 102 205 by 201 result205 p@sheightresult

p@sheightbbh p@swidthbbw

@rheight p@srheightp@sheight @rwidth p@srwidthp@swidth p@scost<psdraft

@clip

@prologfile

@postlogfile

to p@srheight true sp to p@srwidth true sp

to p@srheight true sp

to p@srwidth true sp

p@sfile

• Common (Dumpable)

  • This abstract class forms the base of the external, parallel hierarchy and defines the interface(s) whose behaviors will be polymorphically projected and used by clients.
• ConcreteCommon<ConcreteType> (ConcreteDumpable)

  • This parameterized subclass of Common implements the interface(s) defined in Common. A typical implementation will simply forward the call to the appropriate SignatureAdapter template function.
• SignatureAdapter::request<ConcreteType> (::dump<>)

  • The template function adapter forwards requests to the object. In some cases, e.g., where the signature of specificRequest is consistent, this feature may not be needed. However, if specificRequest has different signatures within several Concrete classes, the SignatureAdapter can be used to insulate ConcreteCommon from the differences.
• ConcreteType

  • The ConcreteType classes define specificRequest operations that perform the desired tasks. Although Concrete classes need not be related by inheritance, the External Polymorphism pattern allows you to treat all or some of their methods polymorphically.