Re: global variables - an alternate approach

From:

Paul Bibbings <paul.bibbings@gmail.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Sat, 13 Feb 2010 17:24:28 CST

Message-ID:

<87fx54ddio.fsf@gmail.com>

forums_mp@hotmail.com writes:

For starters the emphasis is on 'global' variables common to muliple
translation units

Coding standard states that global variables should be defined as
static variables' within a class at public scope. One instance of
this class should exist and the recommendation is to use the singleton
design patten. IOW:

//common_data_b.h
# ifndef COMMON_DATA_B_H
# define COMMON_DATA_B_H

#include <iostream>
class common_data_b {
public :
   static int const a = 5 ;
   static const double pi ;
   static
   common_data_b& intance() {
     static common_data_b cd_b;
     return cd_b;
   }
};
#endif

Having not come across this `idiom' before, I have to say that at the
outset I'm a little unsure about it too. I'm trying to figure (albeit
with a very tired head on) what the advantage of the singleton pattern
gives here, in returning a reference to a single static instance of an
object whose only purpose is to expose two public static data members,
access to which do not require instantiation of common_data_b at all.
Or am I just /too/ tired today?

Regards

Paul Bibbings

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