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Date: Wed, 26 Aug 2009 16:49:05 +0200
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] Coding style,
	C++ compatible code (was Re: [Qemu-devel]
	[PATCH 02/22] eepro100: cast a void * makes no sense)
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To: Stefan Weil <weil@mail.berlios.de>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Markus Armbruster <armbru@redhat.com>, qemu-devel@nongnu.org

   Hi,

> Why don't we declare structures like this: typedef struct { ... } T;?
> I suggest this to be the new coding style for structure declarations
> because it is shorter, C++ compatible and unambiguous.

There are quite a few cases where this will simply not work.  They 
usually use a slightly different declaration style though:

typedef struct T T;
struct T {
   /* stuff here */
};

Reasons why this is used/needed:

(1) structs pointing to each other, like this:

typedef struct A A;
typedef struct B B;

struct A {
   B *b;
};
struct B {
   A *a;
};

(2) keep the struct private, let others pass around pointers
     to the struct in a typesafe way though:

header file:

typedef struct T T;
T* get_foo(args);
int do_something_with_foo(T*);

source file:

struct T {
   /* stuff here */
};

cheers,
   Gerd