parameter.h File Reference

macro for using C++11 enum class as DMLC parameter More...

#include <dmlc/parameter.h>
#include <xgboost/base.h>
#include <string>
#include <type_traits>

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Classes
struct	xgboost::XGBoostParameter< Type >

Namespaces
	xgboost
	namespace of xgboost

Macros
#define	DECLARE_FIELD_ENUM_CLASS(EnumClass)
	Specialization of FieldEntry for enum class (backed by int) More...

Detailed Description

macro for using C++11 enum class as DMLC parameter

Copyright 2018 by Contributors

Author

Hyunsu Philip Cho

Macro Definition Documentation

DECLARE_FIELD_ENUM_CLASS

#define DECLARE_FIELD_ENUM_CLASS

(

EnumClass

)

Value:

namespace dmlc {  \
namespace parameter {  \
template <>  \
class FieldEntry<EnumClass> : public FieldEntry<int> {  \
 public:  \
  FieldEntry<EnumClass>() {  \
    static_assert(  \
      std::is_same<int, typename std::underlying_type<EnumClass>::type>::value,  \
      "enum class must be backed by int");  \
    is_enum_ = true;  \
  }  \
  using Super = FieldEntry<int>;  \
  void Set(void *head, const std::string &value) const override {  \
    Super::Set(head, value);  \
  }  \
  inline FieldEntry<EnumClass>& add_enum(const std::string &key, EnumClass value) {  \
    Super::add_enum(key, static_cast<int>(value));  \
    return *this;  \
  }  \
  inline FieldEntry<EnumClass>& set_default(const EnumClass& default_value) {  \
    default_value_ = static_cast<int>(default_value);  \
    has_default_ = true;  \
    return *this;  \
  }  \
  inline void Init(const std::string &key, void *head, EnumClass& ref) {  /* NOLINT */  \
    Super::Init(key, head, *reinterpret_cast<int*>(&ref));  \
  }  \
};  \
}  /* namespace parameter */  \
}  /* namespace dmlc */

Specialization of FieldEntry for enum class (backed by int)

Use this macro to use C++11 enum class as DMLC parameters

Usage:

// enum class must inherit from int type
enum class Foo : int {
  kBar = 0, kFrog = 1, kCat = 2, kDog = 3
};
 
// This line is needed to prevent compilation error
DECLARE_FIELD_ENUM_CLASS(Foo);
 
// Now define DMLC parameter as usual;
//   enum classes can now be members.
struct MyParam : dmlc::Parameter<MyParam> {
  Foo foo;
  DMLC_DECLARE_PARAMETER(MyParam) {
    DMLC_DECLARE_FIELD(foo)
      .set_default(Foo::kBar)
      .add_enum("bar", Foo::kBar)
      .add_enum("frog", Foo::kFrog)
      .add_enum("cat", Foo::kCat)
      .add_enum("dog", Foo::kDog);
  }
};
 
DMLC_REGISTER_PARAMETER(MyParam);