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POWhich Typesafe Enum in C++ Are You Using?
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  1. POWhich Typesafe Enum in C++ Are You Using?
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    copied!<p>It is common knowledge that built-in enums in C++ are not typesafe. I was wondering which classes implementing typesafe enums are used out there... I myself use the following "bicycle", but it is somewhat verbose and limited:</p> <p>typesafeenum.h:</p> <pre><code>struct TypesafeEnum { // Construction: public: TypesafeEnum(): id (next_id++), name("") {} TypesafeEnum(const std::string&amp; n): id(next_id++), name(n) {} // Operations: public: bool operator == (const TypesafeEnum&amp; right) const; bool operator != (const TypesafeEnum&amp; right) const; bool operator &lt; (const TypesafeEnum&amp; right) const; std::string to_string() const { return name; } // Implementation: private: static int next_id; int id; std::string name; }; </code></pre> <p>typesafeenum.cpp:</p> <pre><code>int TypesafeEnum::next_id = 1; bool TypesafeEnum::operator== (const TypesafeEnum&amp; right) const { return id == right.id; } bool TypesafeEnum::operator!= (const TypesafeEnum&amp; right) const { return !operator== (right); } bool TypesafeEnum::operator&lt; (const TypesafeEnum&amp; right) const { return id &lt; right.id; } </code></pre> <p>Usage:</p> <pre><code>class Dialog { ... struct Result: public TypesafeEnum { static const Result CANCEL("Cancel"); static const Result OK("Ok"); }; Result doModal(); ... }; const Dialog::Result Dialog::Result::OK; const Dialog::Result Dialog::Result::CANCEL; </code></pre> <p><strong>Addition:</strong> I think I should have been more specific about the requirements. I'll try to summarize them:</p> <p>Priority 1: Setting an enum variable to an invalid value should be impossible (a compile-time error) with no exceptions.</p> <p>Priority 2: Converting an enum value to/from an int should be possible with a single explicit function/method call.</p> <p>Priority 3: As compact, elegant and convenient declaration and usage as possible</p> <p>Priority 4: Converting enum values to and from strings.</p> <p>Priority 5: (Nice to have) Possibility to iterate over enum values.</p>
 

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