Nested Class Definitions Question

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2 total messages Started by Desmond Dsouza Sat, 05 Jan 1991 02:13

#779

Author: Desmond Dsouza
Date: Sat, 05 Jan 1991 02:13

36 lines
1515 bytes

Is it legal to forward declare a class nested in another class?
I believe the following is illegal in C++? If so, why? It is a
useful form of modularity.

class PRINTING_SYS {
  class PRINTER;      // Nested class forward declaration
  class PRINT_QUEUE;  //  "  
public:
  spool();
};

class PRINTING_SYS::PRINTER { ... };
class PRINTING_SYS::PRINT_QUEUE { ... };

According to the ARM:
p. 164
"Except for historical reasons, a class declaration would have been called
a class definition"
i.e. class A {...}; is called a class declaration.

p. 185: "A class may be declared within another class"

p. 187: "Member functions and static data members of a nested class
can be defined in the global scope"

Putting these 3 together it seems that nested class (forward)
declarations are not legal.

---
Desmond.
--

-------------------------------------------------------------------------------
 Desmond D'Souza, MCC CAD Program | ARPA: dsouza@mcc.com | Phone: [512] 338-3324
 Box 200195, Austin, TX 78720 | UUCP: {uunet,harvard,gatech,pyramid}!cs.utexas.edu!milano!cadillac!dsouza

DISCONTINUING comp.std.c++ (was: Nested Class Definitions Question)

#791

Author: Ron Guilmette
Date: Sun, 20 Jan 1991 10:20

29 lines
1557 bytes

In article <DSOUZA.91Jan4201341@optima.cad.mcc.com> dsouza@optima.cad.mcc.com (Desmond Dsouza) writes:
+
+Is it legal to forward declare a class nested in another class?
+I believe the following is illegal in C++? If so, why? It is a
+useful form of modularity.
+
+class PRINTING_SYS {
+  class PRINTER;      // Nested class forward declaration
+  class PRINT_QUEUE;  //  "  
+public:
+  spool();
+};
+
+class PRINTING_SYS::PRINTER { ... };
+class PRINTING_SYS::PRINT_QUEUE { ... };

I have now seen numerous messages posted to this newsgroup which did not
belong here, however I have yet to see any response whatsoever to this
very valid question about a significant C++ standards issue.

What's the problem?  Is there really such a total disinterest in C++
standards issues by readers of usenet news?  Should this newsgroup
be disbanded due to lack of interest?

-- 

// Ron Guilmette  -  C++ Entomologist
// Internet: rfg@ncd.com      uucp: ...uunet!lupine!rfg
// Motto:  If it sticks, force it.  If it breaks, it needed replacing anyway.

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