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注意

Further utility functions can be found in the maxon::DataTypeLib .

Conversion

The maxon::DataType object is used to register and apply specific conversions from and to the defined data type.

• maxon::DataType::AddConversion() : Registers a conversion delegate function from the source type to this maxon::DataType .
• maxon::DataType::Convert() : Converts the source value to the target value.
• maxon::DataType::IsCastableFrom() : Returns true if the given maxon::DataType can be cast into the data type.
• maxon::DataType::IsCastableTo() : Returns true if the data type can be cast in to the given maxon::DataType .

Available conversion types are:

• maxon::CONVERSION_FLAGS::IDENTITY: The conversion contains an identity conversion such as from Vector to Color.
• maxon::CONVERSION_FLAGS::NARROWING : The conversion is a narrowing conversion. The conversion may not always be possible (such as converting a negative maxon::Int 到 maxon::UInt ), then it returns an error.
• maxon::CONVERSION_FLAGS::WIDENING_LOSSY : The conversion is a widening conversion which is always possible, but it might result in loss of precision (a maxon::Float64 can't represent all bits of an maxon::Int64 ).
• maxon::CONVERSION_FLAGS::WIDENING_LOSSLESS : The conversion is a lossless widening conversion.
• maxon::CONVERSION_FLAGS::EXPANDING : The conversion contains a expanding conversion such as from a scalar to a vector.
• maxon::CONVERSION_FLAGS::REDUCING : The conversion contains a reducing conversion such as from a vector to a scalar.

// add conversion maxon::DataType::AddConversion<maxon::Vector, IntegerTriplet>( maxon::CONVERSION_FLAGS::WIDENING_LOSSY , []( maxon::Vector & dest, const IntegerTriplet& src ) -> maxon::Result<void> { dest. x = maxon::Float ( src ._a); dest. y = maxon::Float ( src ._b); dest. z = maxon::Float ( src ._c); return maxon::OK ; }) iferr_return ;

// convert

// prepare data IntegerTriplet triplet; triplet._a = 10; triplet._b = 20; triplet._c = 30;

// get DataType const maxon::DataType dt = maxon::GetDataType<maxon::Vector>(); if (dt) { // convert maxon::Vector vec; maxon::Generic* const generic = reinterpret_cast< maxon::Generic* > (&vec); const maxon::ConstDataPtr ptr = maxon::ConstDataPtr (triplet); const maxon::CONVERSION_FLAGS ignore = maxon::CONVERSION_FLAGS::NONE ; dt. 转换 (* generic , ptr, ignore) iferr_return ; DiagnosticOutput ( "Vector: @" , vec); }

DataType Comparison

Two maxon:DataType objects can be compared using the "==" operator or with some more sophisticated functions:

• maxon::DataType::IsBaseOfOrSame() : Returns true if this type is a base type of the given maxon::DataType .
• maxon::DataType::IsSimilar() : Returns true if this type is similar to the given maxon::DataType .

Value Comparison

使用 maxon::DataType object it is also possible two compare two object of this data type:

• maxon::DataType::IsEqual() : Returns true if the two given objects are equal.
• maxon::DataType::Compare() : Returns the compare result of the two given objects.
• maxon::DataType::GetHashCode() : Returns a hash value for the given object.

Construct

The maxon::DataType object can be used to create new object instances of the define type:

• maxon::DataType::Create(): Returns a new instance of the type.
• maxon::DataType::Construct() : Creates multiple instances of the type.
• maxon::DataType::MoveConstruct(): Moves constructs multiple instances of the type.
• maxon::DataType::Destruct() : Destroys multiple instances of the type.
• maxon::DataType::MoveFrom(): Moves multiple instances of the type to a target location.
• maxon::DataType::CopyFrom(): Copies multiple instances of the type to the target location.

// compare to legit data types const maxon::DataType int_dt = maxon::GetDataType<maxon::Int>(); const maxon::DataType uint_dt = maxon::GetDataType<maxon::UInt>(); const maxon::Bool isIntDataType = dt == int_dt; const maxon::Bool isUIntDataType = dt == uint_dt; if (!(isIntDataType || isUIntDataType)) return maxon::UnexpectedError( MAXON_SOURCE_LOCATION , "Template function used with invalid type." _s);

// create numbers dt-> Construct (mem, 0, count); return maxon::OK ; }

Interfaces

Also interfaces are registered as a maxon::DataType .

• maxon::DataType::GetImplementation(): Returns the interface implementation of this type.
• maxon::DataType::GetInterfaces(): Returns the interfaces of this object type.

Disc I/O

Data stored in an object of a given maxon::DataType can be written to a file. How this is done is described by a maxon::DataSerializeInterface 对象。

• maxon::DataType::DescribeIO() : Describes all elements of this data type for I/O operations.

特性

The maxon::DataType object gives access to various properties of the described data type:

• maxon::DataType::ToString() : Returns a maxon::String of the data type name.
• maxon::DataType::GetId() : Returns the unique maxon::Id for the data type.

The maxon::DataType object also provides information on the type of data:

• maxon::DataType::GetSize() : Returns the size of values of the data type.
• maxon::DataType::GetAlignment() : Returns the alignment of values of the data type.
• maxon::DataType::GetValueKind() : Returns the kind of values of this data type. See maxon::VALUEKIND .
• maxon::DataType::CheckValueKind() : Returns true if the data type is of the given maxon::VALUEKIND .

It is possible to register a data type using MAXON_DATATYPE_REGISTER_STRUCT . This will inform Cinema 4D about public members of the type. The maxon::DataType object can be used to list these public members.

• maxon::DataType::GetTupleType() : Returns the underlying tuple type of this data type.
• maxon::DataType::GetTypeArguments() : Returns the member names for the underlying structure type.

另请参阅 maxon::TypeArguments and maxon::Member .

// check if structure if (kind & maxon::VALUEKIND::STRUCT ) { const maxon::TupleDataType tupleData = dt. GetTupleType (); if (tupleData) { const maxon::TypeArguments & args = tupleData. GetTypeArguments ();

// loop through all members for ( maxon::Int i = 0; i < args. count ; ++i) { const maxon::Member member = args. args [i]; const maxon::Id memberName = member. name ; const maxon::DataType memberType = member. type ; DiagnosticOutput ( "Member @ (@)" , memberName, memberType); } } }

延伸阅读

• 数据 & 算法
• MAXON Data Type
• Data Manual