Changeset bfd7b30 for doc/theses/andrew_beach_MMath

Timestamp:

Aug 12, 2021, 8:07:39 AM (3 years ago)

Author:

Peter A. Buhr <pabuhr@…>

Branches:

ADT, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

93d0ed3

Parents:

b42d0ea

Message:

add virtual type examples and figure

Location:

doc/theses/andrew_beach_MMath

Files:

• features.tex (modified) (2 diffs)
• vtable.fig (added)

doc/theses/andrew_beach_MMath/features.tex

@@ -130 +130 @@
 
 \section{Virtuals}
+\label{s:Virtuals}
 Virtual types and casts are not part of \CFA's EHM nor are they required for
 an EHM.
 However, one of the best ways to support an exception hierarchy
 is via a virtual hierarchy and dispatch system.
-
 Ideally, the virtual system should have been part of \CFA before the work
 on exception handling began, but unfortunately it was not.
@@ -149 +149 @@
 number of children.
 Any type that belongs to any of these trees is called a virtual type.
-
+For example, the following hypothetical syntax creates two virtual-type trees.
+\begin{flushleft}
+\lstDeleteShortInline@
+\begin{tabular}{@{\hspace{20pt}}l@{\hspace{20pt}}l}
+\begin{cfa}
+vtype V0, V1(V0), V2(V0);
+vtype W0, W1(W0), W2(W1);
+\end{cfa}
+&
+\raisebox{-0.6\totalheight}{\input{vtable}}
+\end{tabular}
+\lstMakeShortInline@
+\end{flushleft}
 % A type's ancestors are its parent and its parent's ancestors.
 % The root type has no ancestors.
 % A type's descendants are its children and its children's descendants.
-
-Every virtual type also has a list of virtual members. Children inherit
+Every virtual type also has a pointer to a virtual table with list of virtual members. Children inherit
 their parent's list of virtual members but may add new members to it.
-It is important to note that these are virtual members, not virtual methods
-of object-orientated programming, and can be of any type.
+For example,
+\begin{cfa}
+vtable W0 | { int ?<?( int, int ); int ?+?( int, int ); }
+vtable W1 | { int w, int ?==?( int, int ); int ?-?( int, int ); }
+\end{cfa}
+creates a virtual table for @W0@ initialized with the matching @<@ and @+@
+operations visible at this declaration.  Similarly, @W1@ is initialized with
+@<@ and @+@ from the inheritance with @W0@, plus the @==@ and @-@ operations
+visible at this declaration. It is important to note that these are virtual
+members, not virtual methods of object-orientated programming, and can be of
+any type.
 
 \PAB{Need to look at these when done.