[RESOLVED] Template Horrors
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  1. #1
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    [RESOLVED] Template Horrors

    It seems all my problems involve templates. Anyways, my problem is whenever and wherever I put:
    Code:
    std::vector<T>::iterator iter;
    I get the compiler error:
    error: expected ';' before 'iter'

    I've tried putting the above code directly in a template method of a template class and directly as a member of the same class in it's definition. Each time I get the same error where it occures. I feel stupid because I think I'm missing something very fundamental here. Can anyone help? Thanks.
    Intel Core Duo Macbook w/ Mac OS 10.5.6
    gcc 4.2.1 (i386-apple-darwin9.1.0) and Xcode 3.1.1

  2. #2
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    Re: Template Horrors

    My guess is that you need to disambiguate with typename since the nested name iterator depends on T, which is presumably the template parameter. For example:
    Code:
    typename std::vector<T>::iterator iter;
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  3. #3
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    Re: Template Horrors

    Would you mind elaborating a bit on this? I'm not sure what this will do.
    Intel Core Duo Macbook w/ Mac OS 10.5.6
    gcc 4.2.1 (i386-apple-darwin9.1.0) and Xcode 3.1.1

  4. #4
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    Re: Template Horrors

    We need to see the bigger context in which that's being used. Is this inside another template class? etc... Post all relevant code.

    gg

  5. #5
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    Re: Template Horrors

    Well, I don't think much of it is very relevant, but here you go:
    Code:
    template<class T> class SomeClass
    {
    public:
        void someMethod (void)
        {
            ...
            std::vector<T>::iterator iter;   // I get the error everywhere. Whether I put it here...
            ...
        }
    protected:
        std::vector<T>::iterator iter;   // .. Or here, it doesn't matter
    };
    Edit:
    It looks like laserlight was right, because it will work now. It's just that I don't understand why I needed to do that.
    Intel Core Duo Macbook w/ Mac OS 10.5.6
    gcc 4.2.1 (i386-apple-darwin9.1.0) and Xcode 3.1.1

  6. #6
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    Re: Template Horrors

    Quote Originally Posted by Etherous
    It's just that I don't understand why I needed to do that.
    Because std::vector<T>::iterator can be interpreted as a non-type name (e.g., a variable name) or as a type name, and the rules say that it should be interpreted as a non-type name by default.
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  7. #7
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    Re: Template Horrors

    Quote Originally Posted by laserlight View Post
    Because std::vector<T>::iterator can be interpreted as a non-type name (e.g., a variable name) or as a type name, and the rules say that it should be interpreted as a non-type name by default.
    Okay, this is making more sense. For anyone else with this problem, I just stumbled on a good bit of reading that explains this very well:
    http://pages.cs.wisc.edu/~driscoll/typename.html
    Last edited by Etherous; March 21st, 2009 at 03:23 PM.
    Intel Core Duo Macbook w/ Mac OS 10.5.6
    gcc 4.2.1 (i386-apple-darwin9.1.0) and Xcode 3.1.1

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