NAME

std::messages::open,std::messages::do_open - std::messages::open,std::messages::do_open

Synopsis

Defined in header <locale>
public:
catalog open( const std::basic_string<char>& name, const std::locale& loc ) (1)
const;
protected:
virtual catalog do_open( const std::basic_string<char>& name, const (2)
std::locale& loc ) const;

1) Public member function, calls the protected virtual member function do_open of
the most derived class.

2) Obtains a value of type catalog (inherited from std::messages_base), which can be
passed to get() to retrieve messages from the message catalog named by name. This
value is usable until passed to close().

Parameters

name - name of the message catalog to open
a locale object that provides additional facets that may be required to read
loc - messages from the catalog, such as std::codecvt to perform wide/multibyte
conversions

Return value

The non-negative value of type catalog that can be used with get() and close().
Returns a negative value if the catalog could not be opened.

Notes

On POSIX systems, this function call usually translates to a call to catopen(). In
GNU libstdc++, it calls textdomain.

The actual catalog location is implementation-defined: for the catalog "sed"
(message catalogs installed with the Unix utility 'sed') in German locale, for
example, the file opened by this function call may be
/usr/lib/nls/msg/de_DE/sed.cat, /usr/lib/locale/de_DE/LC_MESSAGES/sed.cat, or
/usr/share/locale/de/LC_MESSAGES/sed.mo.

Example

The following example demonstrated retrieval of messages: on a typical GNU/Linux
system it reads from /usr/share/locale/de/LC_MESSAGES/sed.mo

// Run this code

#include <iostream>
#include <locale>

int main()
{
std::locale loc("de_DE.utf8");
std::cout.imbue(loc);
auto& facet = std::use_facet<std::messages<char>>(loc);
auto cat = facet.open("sed", loc);
if(cat < 0 )
std::cout << "Could not open german \"sed\" message catalog\n";
else
std::cout << "\"No match\" in German: "
<< facet.get(cat, 0, 0, "No match") << '\n'
<< "\"Memory exhausted\" in German: "
<< facet.get(cat, 0, 0, "Memory exhausted") << '\n';
facet.close(cat);
}

Possible output:

"No match" in German: Keine Übereinstimmung
"Memory exhausted" in German: Speicher erschöpft