Introduction

A schema variant is an object used by schema that can hold a single piece of data that can be reassigned with a new value (And possibly type).

The supported types are:

Type	Description	Function to set
bool	A standard C++ boolean type with true and false values	SchemaVariantSetBool
double	A double precision floating point	SchemaVariantSetNumber
LPCWSTR	A Unicode string	SchemaVariantSetString
void *	Any arbitrary data	SchemaVariantSetPointer

Creating/Destroying

To create a schema variant you call SchemaVariantCreate followed by a call to set some data into it with the appropriate function. Until you have set data into the newly created schema variant the type of the schema variant will be SystemType::Undefined. Calling schema variant functions on undefined schema variants may fail.

When you are finished with a schema variant call SchemaVariantDelete to free the schema variant.

void MakeVariant()
{
	SchemaVariantHandle variant = SchemaVariantCreate();	// Type is SystemType::Undefined
	SchemaVariantSetNumber(variant, 123.45f);				// Type is now SystemType::Number, value 123.45
	
	SchemaVariantDelete(variant);							// Remember to delete the variant when finished
}

Setting/Changing

You can set/change the value and type of a schema variant with the following calls

Function	Description	Resulting type
SchemaVariantSetBool	Sets the schema variant to a boolean value	SystemType::Boolean
SchemaVariantSetNumber	Sets the schema variant to a double value	SystemType::ANumber
SchemaVariantSetString	Sets the schema variant to a string value	SystemType::AString
SchemaVariantSetPointer	Sets the schema variant to a pointer	The user defined type
SchemaVariantSet	Sets a schema variant from another schema variant	Same as source schema variant

void ChangeVariant()
{
	SchemaVariantHandle variant = SchemaVariantCreate();	// Type is SystemType::Undefined
	SchemaVariantSetNumber(variant, 123.45f);				// Type is now SystemType::Number, value 123.45
	
	SchemaVariantSetString(variant, L"Hello World");		// Type is now SystemType::AString
	SchemaVariantDelete(variant);							// Remember to delete the variant when finished
}

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