| 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> |
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| 2 | <HTML> |
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| 3 | <HEAD> |
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| 4 | <TITLE>Flushable</TITLE> |
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| 5 | <LINK REL="stylesheet" HREF="../../../../boost.css"> |
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| 6 | <LINK REL="stylesheet" HREF="../theme/iostreams.css"> |
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| 7 | </HEAD> |
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| 8 | <BODY> |
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| 9 | |
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| 10 | <!-- Begin Banner --> |
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| 11 | |
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| 12 | <H1 CLASS="title">Flushable</H1> |
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| 13 | <HR CLASS="banner"> |
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| 14 | |
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| 15 | <!-- End Banner --> |
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| 16 | |
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| 17 | <H2>Description</H2> |
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| 18 | |
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| 19 | <P> |
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| 20 | A Flushable Sink or OutputFilter provides a means for the user to request that all buffered characters be sent downstream. |
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| 21 | </P> |
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| 22 | |
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| 23 | <H2>Refinement of</H2> |
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| 24 | |
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| 25 | <A NAME="types"></A> |
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| 26 | <H2>Associated Types</H2> |
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| 27 | |
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| 28 | <P>Same as <A HREF="filter.html#types">Filter</A> or <A HREF="device.html#types">Device</A>, with the following additional requirement:</P> |
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| 29 | |
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| 30 | <TABLE CELLPADDING="5" BORDER="1"> |
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| 31 | <TR><TD>Category</TD><TD>A type convertible to <A HREF="../guide/traits.html#category_tags"><CODE>flushable_tag</CODE></A></TD></TR> |
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| 32 | </TABLE> |
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| 33 | |
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| 34 | |
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| 35 | <H2>Notation</H2> |
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| 36 | |
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| 37 | <TABLE CELLPADDING="2"> |
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| 38 | <TR><TD><CODE>F</CODE></TD><TD>-</TD><TD>A type which is a model of Flushable</TD></TR> |
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| 39 | <TR><TD><CODE>D</CODE></TD><TD>-</TD><TD>A type which is a model of <A HREF="device.html">Sink</A>, with the same character type as <CODE>F</CODE></TD></TR> |
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| 40 | <TR><TD><CODE>f</CODE></TD><TD>-</TD><TD>Object of type <CODE>F</CODE></TD></TR> |
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| 41 | <TR><TD><CODE>d</CODE></TD><TD>-</TD><TD>Object of type <CODE>D</CODE></TD></TR> |
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| 42 | </TABLE> |
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| 43 | |
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| 44 | <H2>Valid Expressions / Semantics</H2> |
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| 45 | |
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| 46 | <TABLE CELLPADDING="5" BORDER="1"> |
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| 47 | <TR><TH>Expression</TH><TH>Expression Type</TH><TH>Precondition</TH><TH>Semantics</TH></TR> |
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| 48 | <TR> |
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| 49 | <TD> |
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| 50 | <PRE CLASS="plain_code"><CODE><A HREF="../functions/flush.html#flush_device">boost::iostreams::flush</A>(f)</CODE></PRE> |
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| 51 | </TD> |
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| 52 | <TD><CODE>bool</CODE></TD> |
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| 53 | <TD>Category convertible to <A HREF="../guide/traits.html#category_tags"><CODE>device_tag</CODE></A></TD> |
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| 54 | <TD> |
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| 55 | Attempts to send all buffered characters downstream, returning <CODE>true</CODE> unless an error occurs.<A CLASS='footnote_ref' NAME='note_1_ref' HREF='#note_1'><SUP>[1]</SUP></A> |
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| 56 | </TD> |
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| 57 | </TR> |
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| 58 | <TR> |
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| 59 | <TD> |
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| 60 | <PRE CLASS="plain_code"><CODE><A HREF="../functions/flush.html#flush_filter">boost::iostreams::flush</A>(f, d)</CODE></PRE> |
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| 61 | </TD> |
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| 62 | <TD><CODE>bool</CODE></TD> |
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| 63 | <TD>Category convertible to <A HREF="../guide/traits.html#category_tags"><CODE>filter_tag</CODE></A></TD> |
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| 64 | <TD> |
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| 65 | <P> |
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| 66 | Attempts to write all buffered characters to d, returning <CODE>true</CODE> if all buffered characters were written. |
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| 67 | </P> |
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| 68 | </TD> |
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| 69 | </TR> |
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| 70 | </TABLE> |
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| 71 | |
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| 72 | <H2>Exceptions</H2> |
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| 73 | |
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| 74 | <P> |
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| 75 | Errors which occur during the execution of <A CLASS="code" HREF="../functions/flush.html"><CODE>flush</CODE></A> are be indicated by throwing exceptions. Such exceptions are caught and ignored if they occur during the execution of stream or stream buffer destructor. |
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| 76 | </P> |
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| 77 | |
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| 78 | <H2>Models</H2> |
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| 79 | |
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| 80 | <P>Several of the Filters and Devices provided by the Iostreams library are Flushable, but this is an implementation detail.</P> |
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| 81 | |
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| 82 | <HR> |
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| 83 | |
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| 84 | <P> |
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| 85 | <A CLASS='footnote_ref' NAME='note_1' HREF='#note_1_ref'><SUP>[1]</SUP></A>It was noticed late in developement that to be consistent with the policy of reporting errors using exceptions (<I>see</I> <A HREF='../guide/exceptions.html'>Exceptions</A>), <CODE>flush</CODE> should have been specified to return <CODE>void</CODE> when invoked on a Device. Until the specification is changed, Devices should always return <CODE>true</CODE> when flushed. |
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| 86 | </P> |
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| 87 | |
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| 88 | <!-- Begin Footer --> |
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| 89 | |
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| 90 | <HR> |
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| 91 | <P CLASS="copyright">Revised |
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| 92 | <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan --> |
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| 93 | 20 May, 2004 |
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| 94 | <!--webbot bot="Timestamp" endspan i-checksum="38504" --> |
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| 95 | </P> |
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| 96 | |
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| 97 | <P CLASS="copyright">© Copyright <A HREF="http://www.kangaroologic.com" TARGET="_top">Jonathan Turkanis</A>, 2004</P> |
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| 98 | <P CLASS="copyright"> |
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| 99 | Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <A HREF="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>) |
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| 100 | </P> |
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| 101 | |
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| 102 | <!-- End Footer --> |
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| 103 | |
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| 104 | </BODY> |
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