| <HTML> |
| <HEAD> |
| <TITLE>A Phone Number Formatting Facet Class</TITLE> |
| <LINK REL=StyleSheet HREF="../rw.css" TYPE="text/css" TITLE="Apache stdcxx Stylesheet"></HEAD> |
| <BODY BGCOLOR=#FFFFFF> |
| <A HREF="26-2.html"><IMG SRC="images/bprev.gif" WIDTH=20 HEIGHT=21 ALT="Previous file" BORDER=O></A><A HREF="noframes.html"><IMG SRC="images/btop.gif" WIDTH=56 HEIGHT=21 ALT="Top of Document" BORDER=O></A><A HREF="booktoc.html"><IMG SRC="images/btoc.gif" WIDTH=56 HEIGHT=21 ALT="Contents" BORDER=O></A><A HREF="tindex.html"><IMG SRC="images/bindex.gif" WIDTH=56 HEIGHT=21 ALT="Index page" BORDER=O></A><A HREF="26-4.html"><IMG SRC="images/bnext.gif" WIDTH=25 HEIGHT=21 ALT="Next file" BORDER=O></A><DIV CLASS="DOCUMENTNAME"><B>Apache C++ Standard Library User's Guide</B></DIV> |
| <H2>26.3 A Phone Number Formatting Facet Class</H2> |
| <P>Now that we have locales and facets in C++, we can encapsulate the locale-dependent parsing and formatting of telephone numbers into a new facet class. Let's focus on formatting in this example. We call the new facet class <SAMP>phone_put</SAMP>, analogous to <SAMP>time_put</SAMP>, <SAMP>money_put</SAMP>, etc.</P> |
| <A NAME="idx589"><!></A> |
| <P>The <SAMP>phone_put</SAMP> facet class serves solely as a base class for facet classes that actually implement the locale-dependent formatting. The relationship of class <SAMP>phone_put</SAMP> to the other facet classes is illustrated in <A HREF="26-3.html#Figure 13">Figure 13</A>:</P> |
| <A NAME="idx590"><!></A> |
| <H4><A NAME="Figure 13">Figure 13: The relationship of the phone_put facet to the implementing facets</A></H4> |
| |
| <P><IMG SRC="images/stdlibug-Locales11.gif" WIDTH=555 HEIGHT=226></P> |
| <A NAME="idx591"><!></A> |
| <P>Here is a first tentative declaration of the new facet class <SAMP>phone_put</SAMP>:</P> |
| |
| <UL><PRE> |
| class phone_put: public std::locale::facet { // 1 |
| public: |
| static std::locale::id id; // 2 |
| typedef std::string string_type; |
| |
| phone_put (std::size_t refs = 0) |
| : std::locale::facet (refs) { } // 3 |
| |
| string_type put (const string_type &cntryName, |
| const string_type &areaCode, |
| const string_type &extension) const; // 4 |
| }; |
| |
| </PRE></UL> |
| <TABLE CELLPADDING="3"> |
| |
| <TR VALIGN="top"><TD><SAMP>//1</SAMP></TD><TD>Derive from the base class <SAMP>std::locale::facet</SAMP>, so that a locale object is able to maintain instances of our new phone facet class. |
| <TR VALIGN="top"><TD><SAMP>//2</SAMP></TD><TD>New base facet classes need to define a static data member <SAMP>id</SAMP> of type <SAMP>std::locale::id</SAMP>. |
| <TR VALIGN="top"><TD><SAMP>//3</SAMP></TD><TD>Define a constructor that takes the reference count that is handed over to the base class. |
| <TR VALIGN="top"><TD><SAMP>//4</SAMP></TD><TD>Define a function <SAMP>put()</SAMP> that does the actual formatting. |
| </TABLE> |
| |
| <BR> |
| <HR> |
| <A HREF="26-2.html"><IMG SRC="images/bprev.gif" WIDTH=20 HEIGHT=21 ALT="Previous file" BORDER=O></A><A HREF="noframes.html"><IMG SRC="images/btop.gif" WIDTH=56 HEIGHT=21 ALT="Top of Document" BORDER=O></A><A HREF="booktoc.html"><IMG SRC="images/btoc.gif" WIDTH=56 HEIGHT=21 ALT="Contents" BORDER=O></A><A HREF="tindex.html"><IMG SRC="images/bindex.gif" WIDTH=56 HEIGHT=21 ALT="Index page" BORDER=O></A><A HREF="26-4.html"><IMG SRC="images/bnext.gif" WIDTH=20 HEIGHT=21 ALT="Next file" BORDER=O></A> |
| |
| <!-- Google Analytics tracking code --> |
| <script src="http://www.google-analytics.com/urchin.js" type="text/javascript"> |
| </script> |
| <script type="text/javascript"> |
| _uacct = "UA-1775151-1"; |
| urchinTracker(); |
| </script> |
| <!-- end of Google Analytics tracking code --> |
| |
| </BODY> |
| </HTML> |
