Tools.h++ Manual

104011 Tandem Computers Incorporated 4-3
4
The Standard C Library provides, with <locale.h> , some facilities to
accommodate differences in currency, number, date, and time formats, but it is
maddeningly incomplete. It offers no help for conversion from strings to these
types, and is practically impossible to use if you must do conversions
involving two or more locales. Common time zone facilities (such as those
defined in POSIX.1) are similarly limited, usually offering no way to compute
wall clock time for other locations, or even for the following year in the same
location.
4.1 RWLocale and RWZone
Tools.h++ addresses these problems with the abstract classes RWLocale and
RWZone . If you have used RWDate you have used RWLocale already, perhaps
unknowingly. Every time you convert a date or time to or from a string, a
default argument carries along a RWLocale reference. This is a reference to a
global instance of the class RWLocaleDefault (derived from RWLocale )
which was created at program startup. To use RWLocale explicitly, construct
your own instance and pass it in place of the default. Similarly, when you
manipulate times, a default RWZone reference is passed along, but you can
substitute your own.
You can also install your own instance of RWLocale or RWZone as the global
default. You can even install your RWLocale instance in a stream (this is
called “imbuing the stream”) so that dates and times inserted on (or extracted
from) that stream are formatted (or parsed) accordingly, without any special
arguments.
Let us look at how all this works, with some examples. Here are the header
files we will use:
#incluce <assert.h>
#include <rw/rstream.h>
#include <rw/cstring.h>
#include <rw/locale.h>
#include <rw/rwdate.h>
#include <rw/rwtime.h>