messages Class

The latest version of this topic can be found at messages Class.

The template class describes an object that can serve as a locale facet to retrieve localized messages from a catalog of internationalized messages for a given locale.

Currently, while the messages class is implemented, there are no messages.

Syntax

template <class CharType>  
class messages : public messages_base;

Parameters

CharType
The type used within a program to encode characters in a locale.

Remarks

As with any locale facet, the static object ID has an initial stored value of zero. The first attempt to access its stored value stores a unique positive value in id.

This facet basically opens a catalog of messages defined in the base class messages_base, retrieves the information required, and closes the catalog.

Constructors

Typedefs

Member Functions

Requirements

Header: <locale>

Namespace: std

messages::char_type

A character type that is used display messages.

typedef CharType char_type;

Remarks

The type is a synonym for the template parameter CharType.

messages::close

Closes the message catalog.

void close(catalog _Catval) const;

Parameters

_Catval
The catalog to be closed.

Remarks

The member function calls do_close(_ Catval).

messages::do_close

A virtual function called to lose the message catalog.

virtual void do_close(catalog _Catval) const;

Parameters

_Catval
The catalog to be closed.

Remarks

The protected member function closes the message catalog _Catval, which must have been opened by an earlier call to do_open.

_Catval must be obtained from a previously opened catalog that is not closed.

Example

See the example for close, which calls do_close.

messages::do_get

A virtual function called to retrieve the message catalog.

virtual string_type do_get(
    catalog _Catval,
    int _Set,
    int _Message,
    const string_type& _Dfault) const;

Parameters

_Catval
The identification value specifying the message catalog to be searched.

_Set
The first identified used to locate a message in a message catalog.

_Message
The second identified used to locate a message in a message catalog.

_Dfault
The string to be returned on failure.

Return Value

It returns a copy of _Dfault on failure. Otherwise, it returns a copy of the specified message sequence.

Remarks

The protected member function tries to obtain a message sequence from the message catalog _Catval. It may make use of _Set, _Message, and _Dfault in doing so.

Example

See the example for get, which calls do_get.

messages::do_open

A virtual function called to open the message catalog.

virtual catalog do_open(
    const string& _Catname,
    const locale& _Loc) const;

Parameters

_Catname
The name of the catalog to be searched.

_Loc
The locale being searched for in the catalog.

Return Value

It returns a value that compares less than zero on failure. Otherwise, the returned value can be used as the first argument on a later call to get.

Remarks

The protected member function tries to open a message catalog whose name is _Catname. It may make use of the locale _Loc in doing so

The return value should be used as the argument on a later call to close.

Example

See the example for open, which calls do_open.

messages::get

Retrieves the message catalog.

string_type get(
    catalog _CatVal,
    int _Set,
    int _Message,
    const string_type& _Dfault) const;

Parameters

_Catval
The identification value specifying the message catalog to be searched.

_Set
The first identified used to locate a message in a message catalog.

_Message
The second identified used to locate a message in a message catalog.

_Dfault
The string to be returned on failure.

Return Value

It returns a copy of _Dfault on failure. Otherwise, it returns a copy of the specified message sequence.

Remarks

The member function returns do_get( _Catval, _Set, _Message, _Dfault).

messages::messages

The message facet constructor function.

explicit messages(
    size_t _Refs = 0);

protected: messages(
    const char* _Locname,
    size_t _Refs = 0);

Parameters

_Refs
Integer value used to specify the type of memory management for the object.

_Locname
The name of the locale.

Remarks

The possible values for the _Refs parameter and their significance are:

• 0: The lifetime of the object is managed by the locales that contain it.

• 1: The lifetime of the object must be manually managed.

• > 0: These values are not defined.

No direct examples are possible, because the destructor is protected.

The constructor initializes its base object with locale::facet( _Refs).

messages::open

Opens the message catalog.

catalog open(
    const string& _Catname,
    const locale& _Loc) const;

Parameters

_Catname
The name of the catalog to be searched.

_Loc
The locale being searched for in the catalog.

Return Value

It returns a value that compares less than zero on failure. Otherwise, the returned value can be used as the first argument on a later call to get.

Remarks

The member function returns do_open( _Catname, _Loc).

messages::string_type

A type that describes a string of type basic_string containing characters of type CharType.

typedef basic_string<CharType, Traits, Allocator> string_type;

Remarks

The type describes a specialization of template class basic_string whose objects can store copies of the message sequences.

See Also

<locale>
messages_base Class
Thread Safety in the C++ Standard Library