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POArgument conversion in the presence of function templates
primarykey
Id
18499185
data
AcceptedAnswerId
18637782
AnswerCount
1
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CommentCount
1
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CreationDate
2013-08-28T22:15:59.880
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0
LastActivityDate
2013-09-05T13:32:51.353
LastEditDate
2013-09-05T13:03:51.553
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1543154
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1543154
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0
PostTypeId
1
Score
0
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50
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text
Body
I have a set of function templates that depend on two integers. These need to be instantiated, except that one of the function arguments needs to be converted. A conversion operator is provided for the purpose. However the compiler (VS 2013 express preview) refuses to recognize the possibility of conversion. See the code below. In conversion_op.h <pre><code>template<int N> class Proxy { }; template<int M, int N> void func(const Proxy<M>& p1, const Proxy<N>& p2) { } typedef Proxy<1> SpecialProxy; class Orig { SpecialProxy P; public: operator SpecialProxy() const { return P; } }; </code></pre> In conversion_op.cpp <pre><code>#include "conversion_op.h" //template void func(const SpecialProxy&, const SpecialProxy&); //template void func(const SpecialProxy&, const Proxy<2>&); //template void func(const Proxy<2>&, const SpecialProxy&); //template void func(const Proxy<2>&, const Proxy<2>&); int Test() { Orig a; SpecialProxy p1; Proxy<2> p2; func<1,1>(a, p1); //OK func<1,2>(a, p2); //OK func<1,1>(p1, a); //OK func<2,1>(p2, a); //OK func(a, p1); //Error func(a, p2); //Error func(p1, a); //Error func(p2, a); //Error } </code></pre> The error is: "could not deduce template argument for 'const Proxy &' from 'Orig'. Please see declaration of func." I tried replacing <pre><code>operator SpecialProxy() const; </code></pre> by <pre><code>operator const SpecialProxy&() const; </code></pre> but the error remains the same. Also tried explicitly instantiating the needed function (commented out code in conversion_op.cpp), but no luck. Any insight is appreciated. Thank you.
Tags
<c++><function><templates><arguments><type-conversion>
Title
Argument conversion in the presence of function templates
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1. PO
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1. PO
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1. COHaven't been able to find a solution yet. Can anybody help. Thank You.
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