Order of template specializations

[Thomas Matthews]

Hi,

I have a templated class field:
template <typename Value_Type>
class Field
{
public:
Value_Type value;
};

I want to load the value member from an std::istream.
I want to use a special algorithm for string fields,
but the extraction operators for all others.

My question is: does the overloaded function have
to be declared before the template version?

void LoadField(Field <string>& sf, istream & inp)
{
// ...
}

template <typename Value_Type>
void LoadField(Field <Value_Type>& vf, istream & inp)
{
// ...
}

I would like to create specializations for the
Field<string> and place them in a different
translation unit than the one in which Field is
defined.

The idea is that when somebody wants a Field<double>
they don't get all the function declarations for
Field<string>.

This example was simplified from my actual code.
My actual design is:
Field
^
|
Typed_Field (template)
^
|
Sortable_Typed_ Field

typedef Sortable_Typed_ Field<int> Integer_Field;
typedef Sortable_Typed_ Field<string> String_Field;

--
Thomas Matthews

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[Rob Williscroft]

Thomas Matthews wrote in news:73t%b.5013 7$hd3.31340
@newssvr33.news .prodigy.com:

Hi,

I have a templated class field:
template <typename Value_Type>
class Field
{
public:
Value_Type value;
};

I want to load the value member from an std::istream.
I want to use a special algorithm for string fields,
but the extraction operators for all others.

My question is: does the overloaded function have
to be declared before the template version?

No, but it needs to be declared in all TU's that might use it.
void LoadField(Field <string>& sf, istream & inp)
{
// ...
}

template <typename Value_Type>
void LoadField(Field <Value_Type>& vf, istream & inp)
{
// ...
}

I would like to create specializations for the
Field<string> and place them in a different
translation unit than the one in which Field is
defined.
If they're overloads of fully explicit specialization' s then
declare them in a header, and define them elsewhere.

The idea is that when somebody wants a Field<double>
they don't get all the function declarations for
Field<string>.

Just in case:

- A declaration:

int f();

- A Defenition (also a declaration):

int f()
{
}

They need to see all possible declaration's but not all
defenition's.

Rob.
--
http://www.victim-prime.dsl.pipex.com/