Tools for in-place construction

#include "dcmtk/ofstd/ofutil.h"

Tools for in-place construction of objects, e.g. certain OFvariant alternatives.

Type Definitions
typedef unspecified	OFin_place_t
	A type for tagging an in-place constructor as such. More...
template<typename T>
typedef unspecified	OFin_place_type_t(T)
	A type for tagging an in-place constructor for a certain type as such. More...
template<size_t I>
typedef unspecified	OFin_place_index_t(I)
	A type for tagging an in-place constructor based on a certain index as such. More...

Global Constants
OFin_place_t	OFin_place
	A constant of type OFin_place_t that may be used for in-place construction. More...
template<typename T>
OFin_place_type_t(T)	OFin_place<T>
	A constant of type OFin_place_type_t(T) that may be used for in-place construction. More...
template<size_t I>
OFin_place_index_t(I)	OFin_place<I>
	A constant of type OFin_place_index_t(I) that may be used for in-place construction. More...

Type Definition Documentation

typedef unspecified OFin_place_t

A type for tagging an in-place constructor as such.

Usage Example:

template<typename T>
class Wrapper
{
public:
  // Will copy construct the wrapped value from a T.
  Wrapper( const T& t );
 
  // Will in-place construct the value from the given arguments,
  // calling T( arguments... ) internally, without unnecessary
  // copies.
  template<typename... Arguments>
  Wrapper( OFin_place_t, Arguments... arguments );
 
private:
  // ... wrapper implementation ...
};

template<typename T>

typedef unspecified OFin_place_type_t(T)

A type for tagging an in-place constructor for a certain type as such.

Template Parameters

T the type this in-pace constructor handles, i.e. the type that will be constructed.

Note

Pre C++11 compilers do not support alias templates, therefore, OFin_place_type_t is implemented using preprocessor macros internally. This is why you need to use curved brackets instead of angled ones.

Usage Example:

template<typename A,typename B>
class Union
{
public:
  // Will copy construct the wrapped value as an A from a.
  Union( const A& a );
 
  // Will copy construct the wrapped value as a B from b.
  Union( const B& b );
 
  // Will in-place construct the value as an A from the given
  // arguments, calling A( arguments... ) internally, without
  // unnecessary copies.
  template<typename... Arguments>
  Union( OFin_place_type_t(A), Arguments... arguments );
 
  // Will in-place construct the value as a B from the given
  // arguments, calling B( arguments... ) internally, without
  // unnecessary copies.
  template<typename... Arguments>
  Union( OFin_place_type_t(B), Arguments... arguments );
 
private:
  // ... union implementation ...
};

template<size_t I>

typedef unspecified OFin_place_index_t(I)

A type for tagging an in-place constructor for a certain index as such.

Template Parameters

I the index this in-pace constructor handles, i.e. the zero based index of the type that will be constructed.

Note

Pre C++11 compilers do not support alias templates, therefore, OFin_place_index_t is implemented using preprocessor macros internally. This is why you need to use curved brackets instead of angled ones.

Usage Example:

template<typename A,typename B>
class Union
{
public:
  // Will copy construct the wrapped value as an A from a.
  Union( const A& a );
 
  // Will copy construct the wrapped value as a B from b.
  Union( const B& b );
 
  // Will in-place construct the value as an A from the given
  // arguments, calling A( arguments... ) internally, without
  // unnecessary copies.
  // This will even work if A and B refer to the same type.
  template<typename... Arguments>
  Union( OFin_place_index_t(0), Arguments... arguments );
 
  // Will in-place construct the value as a B from the given
  // arguments, calling B( arguments... ) internally, without
  // unnecessary copies.
  // This will even work if A and B refer to the same type.
  template<typename... Arguments>
  Union( OFin_place_index_t(1), Arguments... arguments );
 
private:
  // ... union implementation ...
};

Global Constant Documentation

OFin_place_t OFin_place

A constant of type OFin_place_t that may be used for in-place construction.

Remarks

OFin_place is actually an overloaded function, but instead of calling it (which one should never do), its address is used as a tag, since the type of its address differs depending on which overload and template parameters are used. See http://en.cppreference.com/w/cpp/utility/in_place for more information.

Usage Example:

template<typename T>
class Wrapper; // see OFin_place_t example
// ...
// will construct an OFString and then copy construct the value in the wrapper
Wrapper<OFString>( "Hello World" );
// will in-place construct the value in the wrapper
Wrapper<OFString>( OFin_place, "Hello World" );
// this also works with multiple arguments:
// will take only the fist five characters of the const char*
Wrapper<OFString>( OFin_place, "Hello World", 5 );

template<typename T>

OFin_place_type_t(T) OFin_place<T>

A constant of type OFin_place_type_t(T) that may be used for in-place construction.

Template Parameters

T the type for selecting an in-pace constructor, i.e. the type that will be constructed.

Remarks

OFin_place is actually an overloaded function, but instead of calling it (which one should never do), its address is used as a tag, since the type of its address differs depending on which overload and template parameters are used. See http://en.cppreference.com/w/cpp/utility/in_place for more information.

Usage Example:

template<typename A,typename B>
class Union; // see OFin_place_type_t example
// ...
// will construct an OFString and then copy construct the value inside the union
Union<int,OFString>( OFString( "Hello World" ) );
// will in-place construct an OFString value inside the union
// with only the fist five characters
Union<int,OFString>( OFin_place<OFString>, "Hello World", 5 );
// will construct an integer value inside the union by casting
// the address of the character array constant to int
Union<int,OFString>( OFin_place<int>, "Hello World" );

template<size_t I>

OFin_place_index_t(I) OFin_place<I>

A constant of type OFin_place_index_t(I) that may be used for in-place construction.

Template Parameters

I the index for selecting an in-pace constructor, i.e. the zero based index of the type that will be constructed.

Remarks

OFin_place is actually an overloaded function, but instead of calling it (which one should never do), its address is used as a tag, since the type of its address differs depending on which overload and template parameters are used. See http://en.cppreference.com/w/cpp/utility/in_place for more information.

Usage Example:

template<typename A,typename B>
class Union; // see OFin_place_index_t example
// ...
// error, cannot determine which constructor shall be used,
// since both take an int
Union<int,int>( 3 );
// will in-place construct an int value inside the union
// tagging it as an A
Union<int,int>( OFin_place<0>, 3 );
// will in-place construct an int value inside the union
// tagging it as a B
Union<int,int>( OFin_place<1>, 3 );