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From: ljz@fxgrp.UUCP (Lloyd Zusman)
Newsgroups: comp.lang.c
Subject: Re: Question on structures
Message-ID: <150@fxgrp.UUCP>
Date: Sun, 8-Nov-87 14:24:27 EST
Article-I.D.: fxgrp.150
Posted: Sun Nov  8 14:24:27 1987
Date-Received: Tue, 10-Nov-87 04:06:30 EST
References: <1025@phoenix.Princeton.EDU> <3022@bunker.UUCP>
Reply-To: ljz@fxgrp.UUCP (Lloyd Zusman)
Followup-To: <3022@bunker.UUCP> garys@bunker.UUCP (Gary M. Samuelson)
Organization: Master Byte Software
Lines: 66
Keywords: Sturctures records

In article <3022@bunker.UUCP> garys@bunker.UUCP (Gary M. Samuelson) writes:
>In article <1025@phoenix.Princeton.EDU> asjoshi@phoenix.UUCP (Amit S. Joshi) writes:
>>I have gotten really tired of typing things like a.b.c.d etc  to refer to
>>elements of a structure ...

There have been several suggestions, most of them involving the use of
#define's for the higher-order structure elements (i.e., "#define foo a.b.c",
thereby causing foo.d to refer to the a.b.c.d element).  But I came up
with a slightly different approach you might want to try ...

#define WITH(Name, Type, Struct)  { Type *Name = &(Struct);
#define ENDWITH                   }

Assume these three macros are defined.  The following program fragment
illustrates how they can be used ...

struct baz {
	int a;
	int b;
	int c;
};

struct bar {
	struct baz i;
	struct baz j;
	struct baz k;
};

struct foo {
	struct bar x;
	struct bar y;
	struct bar z;
};

struct foo p;
struct foo q;
struct foo r;

   .
   .
   .

	WITH (X, struct baz, p.z.i)
		X->a = 1;
		X->b = 2;
		X->c = 3;
	ENDWITH

The above 5 lines translate to

	{ struct baz *X = &(p.z.i);
		X->a = 1;
		X->b = 2;
		X->c = 3;
	}

This is a variation of another method I saw here on the net.  I do it this
way so that you still have a WITH-like environment and the WITH section is
in a separate block of code wherein you can define local variables, etc.

If #define's could be nested within other #define's, you could get rid of
one or two of the arguments to the WITH macro.  Oh well.

-- 
Lloyd Zusman, Master Byte Software, Los Gatos, California
"We take things well in hand."
...!ames!fxgrp!ljz