#include <coherence/util/Optional.hpp>
Inherits Object, and PortableObject.
If a value is present, isPresent() will return true and get() will return the value.
Public Types | |
typedef spec::Handle | Handle |
Optional Handle definition. | |
typedef spec::View | View |
Optional View definition. | |
typedef spec::Holder | Holder |
Optional Holder definition. | |
Public Member Functions | |
virtual Object::Holder | get () const |
Return the object value. | |
virtual bool | isPresent () const |
Return true if there is a value present, otherwise false. | |
virtual Object::Holder | orElse (Object::Holder oh) const |
Return value if present, otherwise, the given object. | |
virtual void | readExternal (PofReader::Handle hIn) |
virtual void | writeExternal (PofWriter::Handle hOut) const |
virtual bool | equals (Object::View v) const |
virtual size32_t | hashCode () const |
Return a hash code value for the Object. This method is supported for the benefit of hash-based containers.
The general contract of
The default implementation is identity based.
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virtual TypedHandle < const String > | toString () const |
Output a human-readable description of this Object to the given stream. Note that when overriding this method the return type must be TypedHandle<const String> rather then String::View. These two types are assignment compatible but not equivalent and declaring the override with String::View will not be a compatible override. coherence::lang::operator<<(std::ostream, Object::View) is defined and will call into the toString method, to output Objects. If a managed String object is desired, the COH_TO_STRING macro can be used to build up a String from streamable contents and is generally how toString() will be implemented.
Object::View vKey = ... Object::View vValue = ... std::cout << vKey << " = " << vValue << std::endl; String::View vs = COH_TO_STRING(vKey << " = " << vValue); The COH_TO_STRING macro is also the most common way to implement the toString method. For example:
virtual TypedHandle<const String> Person::toString() const { return COH_TO_STRING("Name: " << f_sName << " SSN: " << f_nSSN); }
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Static Public Member Functions | |
static Optional::View | empty () |
Return an Optional instance with NULL object value. | |
static Optional::View | of (Object::Holder oh) |
Return an Optional instance with the given object value. | |
static Optional::View | ofNullable (Object::Holder oh) |
Return an Optional instance with the given value, if non-NULL. | |
static Optional::View | emptyInstance () |
Return an empty Optional instance. | |
Protected Member Functions | |
Optional () | |
Default constructor. |
static Optional::View empty | ( | ) | [static] |
static Optional::View of | ( | Object::Holder | oh | ) | [static] |
static Optional::View ofNullable | ( | Object::Holder | oh | ) | [static] |
virtual Object::Holder get | ( | ) | const [virtual] |
Return the object value.
virtual bool isPresent | ( | ) | const [virtual] |
Return true if there is a value present, otherwise false.
virtual Object::Holder orElse | ( | Object::Holder | oh | ) | const [virtual] |
Return value if present, otherwise, the given object.
oh | the default object value to return |
static Optional::View emptyInstance | ( | ) | [static] |