ponder::Value Class Reference

Variant class which is used to wrap values in the Ponder system. More...

#include <value.hpp>

Public Member Functions
	Value ()
	Default constructor, constructs a null value.
template<typename T >
	Value (const T &val)
	Construct the value from a variable of type T. More...
	Value (const Value &other)
	Copy constructor. More...
	Value (Value &&other)
	Move constructor. More...
void	operator= (const Value &other)
	Assignment operator. More...
ValueKind	kind () const
	Return the Ponder runtime kind of the value. More...
template<typename T >
T	to () const
	Convert the value to the type T. More...
template<typename T >
T &	ref ()
	Get a reference to the value data contained. More...
template<typename T >
const T &	cref () const
	Get a const reference to the value data contained. More...
template<typename T >
bool	isCompatible () const
	Check if the stored value can be converted to a type T. More...
template<typename T >
T::result_type	visit (T visitor) const
	Visit the value with a unary visitor. More...
template<typename T >
T::result_type	visit (T visitor, const Value &other) const
	Visit the value and another one with a binary visitor. More...
bool	operator== (const Value &other) const
	Operator == to compare equality between two values. More...
bool	operator!= (const Value &other) const
	Operator != to compare equality between two values. More...
bool	operator< (const Value &other) const
	Operator < to compare two values. More...
bool	operator> (const Value &other) const
	Operator > to compare two values. More...
bool	operator<= (const Value &other) const
	Operator <= to compare two values. More...
bool	operator>= (const Value &other) const
	Operator >= to compare two values. More...

Static Public Attributes
static const Value	nothing
	Special Value instance representing an empty value.

Detailed Description

Variant class which is used to wrap values in the Ponder system.

The Value class can store any type of variable, and supports conversion to any type compatible with the stored type.

ponder::Value v1 = true;
ponder::Value v2 = 10;
ponder::Value v3 = "24.5";
ponder::Value v4 = myObject;
 
bool        b = v1; // b == true
String      s = v2; // s == "10"
float       f = v3; // f == 24.5
MyObject    o = v4; // o == myObject

It also supports unary and binary visitation for type-safe processing depending on the stored type.

Remarks

The set of supported types can be extended by specializing the ponder_ext::ValueMapper template.

See also

ValueVisitor, ponder_ext::ValueMapper

Constructor & Destructor Documentation

Value() [1/3]

template<typename T >

ponder::Value::Value

(

const T &

val

)

Construct the value from a variable of type T.

Parameters

val	Value to store

Value() [2/3]

ponder::Value::Value

(

const Value &

other

)

Copy constructor.

Parameters

other

Value to copy

Value() [3/3]

ponder::Value::Value

(

Value &&

other

)

Move constructor.

Parameters

other

Value to move

Member Function Documentation

cref()

template<typename T >

const T& ponder::Value::cref

(

)

const

Get a const reference to the value data contained.

Get a const reference to the contained value of type T. The user is responsible for ensuring that the type passed is correct. See ref() for a const reference, or to() to convert the value.

Returns

A const reference to the contained data.

isCompatible()

template<typename T >

bool ponder::Value::isCompatible

(

)

const

Check if the stored value can be converted to a type T.

If this function returns true, then calling to<T>() or operator T() will succeed.

Returns

True if conversion is possible, false otherwise

kind()

ValueKind ponder::Value::kind

(

)

const

Return the Ponder runtime kind of the value.

Returns

Type of the value

operator!=()

bool ponder::Value::operator!= ( const Value &  other ) const

inline

Operator != to compare equality between two values.

See also

operator==

Returns

True if both values are not the same, false otherwise

operator<()

bool ponder::Value::operator<

(

const Value &

other

)

const

Operator < to compare two values.

Parameters

other

Value to compare with this

Returns

True if this < other

operator<=()

bool ponder::Value::operator<= ( const Value &  other ) const

inline

Operator <= to compare two values.

Parameters

other

Value to compare with this

Returns

True if this <= other

operator=()

void ponder::Value::operator=

(

const Value &

other

)

Assignment operator.

Parameters

other

Value to assign to this

operator==()

bool ponder::Value::operator==

(

const Value &

other

)

const

Operator == to compare equality between two values.

Two values are equal if their Ponder type and value are equal. It uses the == operator of the stored type.

Parameters

other

Value to compare with this

Returns

True if both values are the same, false otherwise

operator>()

bool ponder::Value::operator> ( const Value &  other ) const

inline

Operator > to compare two values.

Parameters

other

Value to compare with this

Returns

True if this > other

operator>=()

bool ponder::Value::operator>= ( const Value &  other ) const

inline

Operator >= to compare two values.

Parameters

other

Value to compare with this

Returns

True if this >= other

ref()

template<typename T >

T& ponder::Value::ref

(

)

Get a reference to the value data contained.

Get a reference to the contained value of type T. The user is responsible for ensuring that the type passed is correct. See cref() for a non-const reference, or to() to convert the value.

Returns

A non-const reference to the contained data.

to()

template<typename T >

T ponder::Value::to

(

)

const

Convert the value to the type T.

Convert the value contained to the type provided. An exception is throw if the target type is not compatible. The value returned will be a copy. See ref() and cref() for referencing the internal data.

Returns

Value converted to T

Exceptions

BadType

the stored value is not convertible to T

visit() [1/2]

template<typename T >

T::result_type ponder::Value::visit

(

T

visitor

)

const

Visit the value with a unary visitor.

Using this function allows to dispatch an operation depending on the stored type.

Parameters

visitor

Visitor to apply (must inherit from ValueVisitor<type_to_return>)

Returns

Value returned by the visitor

visit() [2/2]

template<typename T >

T::result_type ponder::Value::visit	(	T	visitor,
		const Value &	other
	)		const

Visit the value and another one with a binary visitor.

Using this function allows to dispatch a binary operation depending on the stored type of both values.

Parameters

visitor	Visitor to apply (must inherit from ValueVisitor<type_to_return>)
other	Other value to visit

Returns

Value returned by the visitor

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The documentation for this class was generated from the following file:

• include/ponder/value.hpp