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POdefining hash in tr1 for a template class
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2011-01-23T11:25:06.463
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2011-01-24T05:20:34.663
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2011-01-24T05:20:34.663
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I have the class Gateway. I need to store object of this class in a hash table (using tr1::unordered_set). I've used both the unorderd_set and the class Gateway in another context and they work fine, yet I can't figure how to put a gateway in a unordered set because I can't define its <code>hash</code> function in tr1's namespace. I've tried: (and many other variants) <pre><code>namespace std { namespace tr1 { template<> <typename T> inline size_t hash<(typename Gateway<T>)>::operator()(Gateway<T> gT) const { return gT.getCore()->hash(); //!DOESN't WORK } } </code></pre> The compiler says the this (<code>typename Gateway<T></code>) is wrong. If i take the <code>()</code> off, it assumes the <code>>></code> in the end of <code>hash<typename Gateway<T>>()</code> is the output stream. While in the past i've done this <pre><code>namespace std { namespace tr1 { template<> inline size_t hash<Board>::operator()(Board b) const { return b.hash(); //!WORKS FINE } } } </code></pre> Can anyone shed some light on the problem? Update Thanks for the answer yet there is still a problem The compiler says invalid use of incomplete type <code>struct std::tr1::hash<></code> This sort of error happens when we use the class without its complete definition, yet the class is fully defined before the declaration. I've already used this without templates in a very similar fashion without a problem.
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defining hash in tr1 for a template class
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1. CO`hash<typename Gateway<T>>()` you need a space between `>` characters. c++0x fixes this
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2. COI had a similar issue, following the example at http://en.cppreference.com/w/cpp/utility/hash saved me ;)
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