Newsgroups: comp.os.msdos.djgpp
From: Peter Berdeklis <peter AT atmosp DOT physics DOT utoronto DOT ca>
Subject: Re: Problem with fstreams... 
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Date: Sat, 6 Sep 1997 14:16:28 GMT
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On 3 Sep 1997, Paul Derbyshire wrote:
> How do the enum elements BINARY and so forth become members of ios, as in
> ios::, and not of some enum? Normally the :: thing only applies to member
> functions and instance variables, not to enums. Is the enum actually
> inside the class? Can a class contain structs and subclasses actually
> inside itself so they are only defined in the scope of the class, for
> naming purposes?

The enums in ios are defined within the class.  As a result the enums only
exist within the class' namespace and you have to use explicit scoping to
use them, as in ios::bin.  Note that binary is still a member of an 
enum, called open_mode.

Any class, structure or enum contained inside another exists only inside
the namespace of the surrounding class.  Therefore, it is possible to do
the following: 

struct outside {
	struct inside {
		struct way_inside {
			static int static_data;
			int data;
		} w_ins;
	} ins;
} test_struct;


To get access to the variables static_data and data you would use, resp.:

outside::inside::way_inside::static_data = 1;
test_struct.ins.w_ins = 1;

To create instances of the inner classes you do the following:

outside::inside test_ins;
outside::inside::way_inside test_wins;

---------------
Peter Berdeklis
Dept. of Physics, Univ. of Toronto