From: Nick Bowler <nbowler@draconx.ca>
Date: Fri, 24 Feb 2012 02:51:26 +0000 (-0500)
Subject: Try to fix explanations of "child" declarators in the manual.
X-Git-Tag: v1~72
X-Git-Url: https://git.draconx.ca/gitweb/cdecl99.git/commitdiff_plain/846e987e42c15064fa078e0b708872f7938ceb09

Try to fix explanations of "child" declarators in the manual.

The "child" relationship between declarators is somwhat unintuitive.
Try to explain it properly in the manual.  It's still probably not too
helpful, but it's certainly better than the outright lies that are in
there currently.
---

diff --git a/doc/man/libcdecl.3 b/doc/man/libcdecl.3
index a4dc5f4..00280f5 100644
--- a/doc/man/libcdecl.3
+++ b/doc/man/libcdecl.3
@@ -167,30 +167,46 @@ struct cdecl_declarator {
 };
 .Ed
 .Pp
-There are five types of declarators, distinguished by the
+With the exception of function parameters (which are handled separately),
+declarators form a chain from
+.Do outermost Dc to Do innermost Dc
+declarator.  This relationship is expressed by the
+.Va child
+struct member, which points to the next innermost declarator in the chain.
+Unfortunately, C's declaration syntax is, in a sense, inside-out.  Thus, one
+needs to follow the chain backwards (from innermost to outermost) to understand
+the semantic relationship between declarators in the chain.  In the next
+section, we will use the word
+.Va parent
+to describe this inverted child relationship: we consider the outermost
+declarator's
+.Va parent
+as the declaration's base type (found amongst the declaration specifiers, e.g.
+.Li int , const unsigned long ,
+etc.)
+
+The five types of declarators, described below, are distinguished by the
 .Va type
-struct member.  The union
-.u
+struct member.  Each declarator (except null declarators) carries additional
+information specific to its type, which corresponds to the members of the union
+.Va u .
+
 contains a member for each declarator type (except null) containing additional
-information.  The possible values are described by the following table.  The
-description of the child member is a lie.
+information.  The possible values are described by the following table.
 .Bl -column ".Dv CDECL_DECL_FUNCTION" ".Em Union Member"
 .It Em Declarator Type     Ta Em Union Member Ta Em Description
 .It Dv CDECL_DECL_NULL     Ta (none)          Ta Declares nothing.  This
-declarator has no
+declarator terminates the declarator chain, and has a NULL
 .Va child .
 .It Dv CDECL_DECL_IDENT    Ta Va ident        Ta Declares an identifier.  This
-declarator has no
+declarator has a NULL
 .Va child .
-.It Dv CDECL_DECL_POINTER  Ta Va pointer      Ta Declares a pointer.  The
-.Va child
-member is interpreted as "pointer to child".
-.It Dv CDECL_DECL_ARRAY    Ta Va array        Ta Declares an array.  The
-.Va child
-member is interpreted as "array of child".
-.It Dv CDECL_DECL_FUNCTION Ta Va function     Ta Declares a function.  The
-.Va child
-member is interpreted as "function returning child".
+.It Dv CDECL_DECL_POINTER  Ta Va pointer      Ta Declares a pointer, as in
+.Do pointer to Va parent Dc
+.It Dv CDECL_DECL_ARRAY    Ta Va array        Ta Declares an array, as in
+.Do array of Va parent Dc
+.It Dv CDECL_DECL_FUNCTION Ta Va function     Ta Declares a function, as in
+.Do function returning Va parent Dc
 .El
 .Ss Terminal Declarators
 Null and identifier declarators have no children and are thus leaf nodes.  A