Accessing global constants

This is a discussion on Accessing global constants within the C++ Programming forums, part of the General Programming Boards category; Do you guys think it's a good idea to always use :: before global constants, even if it's not necessary? ...

  1. #1
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    Accessing global constants

    Do you guys think it's a good idea to always use :: before global constants, even if it's not necessary? I like it because it makes it clear that you are using a global variable, and it prevents you from accidentally using a local variable instead by mistake. I've seen some people prefix global variables with g_, but then you might as well use :: in my opinion.

    Then again, the same thing could be said for always using this-> to access member data, which a lot of people probably find to be quite ugly.

  2. #2
    Captain Crash brewbuck's Avatar
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    That sounds like a terrible idea. Why should you deliberate ignore the benefits of namespaces? Namespaces were introduced precisely BECAUSE of name conflicts between globally visible symbols. Placing all global symbols in :: renders namespaces useless.

    If you have a hard time remembering that some variable is global, you could A) improve your memory, B) modify the name with a prefix or suffix, or C) eliminate the need for the global variable.
    Code:
    //try
    //{
    	if (a) do { f( b); } while(1);
    	else   do { f(!b); } while(1);
    //}

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    Quote Originally Posted by brewbuck View Post
    Placing all global symbols in :: renders namespaces useless.
    How is that? If you have a variable x in A then use A::x instead.

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    I would not say that it renders namespaces useless, but rather, it fails to make good use of namespaces.
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    I'm not writing code that will used by anyone else, so I don't care about polluting the global namespace.

    How exactly does it fail to make good use of namespaces then?

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    C++ Witch laserlight's Avatar
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    Quote Originally Posted by Memloop
    I'm not writing code that will used by anyone else, so I don't care about polluting the global namespace.

    How exactly does it fail to make good use of namespaces then?
    You are dumping names in the global namespace. If you are fine with that, so be it, it is your problem when you eventually realise your lack of foresight.
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    Using globals should be pretty rare, so if you find yourself using them enough to feel you need some sort of convention for them, then you are probably over using them.
    It is too clear and so it is hard to see.
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    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by Memloop View Post
    I'm not writing code that will used by anyone else, so I don't care about polluting the global namespace.

    How exactly does it fail to make good use of namespaces then?
    You perform the way you practice. Practice like nobody will ever find value in your code, and your code will always be valueless.
    Code:
    //try
    //{
    	if (a) do { f( b); } while(1);
    	else   do { f(!b); } while(1);
    //}

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    The only reason I could see for using namespaces in this particular case is if I'm linking against some poorly written library that is polluting the global namespace with commonly used names.

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    Malum in se abachler's Avatar
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    Quote Originally Posted by Memloop View Post
    Do you guys think it's a good idea to always use :: before global constants, even if it's not necessary? I like it because it makes it clear that you are using a global variable, and it prevents you from accidentally using a local variable instead by mistake. I've seen some people prefix global variables with g_, but then you might as well use :: in my opinion.

    Then again, the same thing could be said for always using this-> to access member data, which a lot of people probably find to be quite ugly.
    :: is ugly and bad form. I would fire anyone that used it, well, I'd give them a talking to first, and if they kept it up I'd fire them.

    I try to minimize my use of globals, if I need a lot of them, I use a global struct to contain them all. Then I only have to extern a single object to have access to all my global variables.
    Until you can build a working general purpose reprogrammable computer out of basic components from radio shack, you are not fit to call yourself a programmer in my presence. This is cwhizard, signing off.

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    Quote Originally Posted by abachler View Post
    I use a global struct to contain them all.
    Is that global struct in a namespace? Otherwise, I don't see why accessing it with :: is bad form. It's a clear indication that the struct is indeed global. And if you're using it in a namespace, couldn't you just nest another namespace called "globals" or something within the main namespace instead of using a struct? The only difference would be using globals::constant instead of globals.constant.

    As far as I can tell there's no practical difference between prefixing your global variables with g_ and using ::. If there is, please enlighten me.

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