Re: [Boost-users] Non-boost c++ novice help

From: Matt Davies (matt.davies_at_[hidden])
Date: 2006-02-16 11:22:57

I don't think it is the appropriate place.

You need to make it static as well to be in the class:

static const uint64_t mask = 0x12345678

Cheers,
Matt Davies
Rockstar Leeds

-----Original Message-----
From: boost-users-bounces_at_[hidden]
[mailto:boost-users-bounces_at_[hidden]] On Behalf Of Perry Smith
Sent: 16 February 2006 15:43
To: boost-users_at_[hidden]
Subject: [Boost-users] Non-boost c++ novice help

If this is not an appropriate list for this question, please let me  
know.

The books tell me to prefer const to #defines -- but where do you put  
them to have the right scope and not take up space in the object?

What I'd like to have is:

class register {
   void set_mask() { reg |= mask; }

private:
     uint64_t reg;
const uint64_t mask = 0x12345678;
};

But the compiler will not let me do this and even if it did,the mask  
would take up physical space.  I don't want mask (or reg) to be  
visable outside of the class and I want the compiler to use mask as a  
compile time constant that does not consume space after the compile.

I vaguely know about namespace but if I put this inside a namespace,  
then I have to do:

namespace hardware {

const mask = 0x12345678;

class register {
   void set_mask() { reg |= mask; }

private:
     uint64_t reg;
};

};

// .. define a register

hardware::register doddy;

and "mask" is not really private -- just obscured.  I can still do:

int i = hardware::mask;

This just feels like I've taken a wrong turn somewhere.  How would  
this be "properly" done?

Thanks,
Perry

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