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49 lines
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<TITLE>CLHS: System Class BROADCAST-STREAM</TITLE>
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<H1><A REV=MADE HREF="http://www.lispworks.com/"><IMG WIDTH=80 HEIGHT=65 ALT="[LISPWORKS]" SRC="../Graphics/LWSmall.gif" ALIGN=Bottom></A><A REL=TOP HREF="../Front/index.htm"><IMG WIDTH=237 HEIGHT=65 ALT="[Common Lisp HyperSpec (TM)]" SRC="../Graphics/CLHS_Sm.gif" ALIGN=Bottom></A> <A REL=PREV HREF="t_stream.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_stream.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="t_concat.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<A NAME="broadcast-stream"><I>System Class</I> <B>BROADCAST-STREAM</B></A> <P>
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<P>
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<P><B>Class Precedence List:</B><P>
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<P>
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<A REL=DEFINITION HREF="#broadcast-stream"><B>broadcast-stream</B></A>, <A REL=DEFINITION HREF="t_stream.htm#stream"><B>stream</B></A>, <A REL=DEFINITION HREF="t_t.htm#t"><B>t</B></A> <P>
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<P><B>Description:</B><P>
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<P>
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A <A REL=DEFINITION HREF="26_glo_b.htm#broadcast_stream"><I>broadcast stream</I></A> is an <A REL=DEFINITION HREF="26_glo_o.htm#output"><I>output</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>stream</I></A> which has associated with it a set of zero or more <A REL=DEFINITION HREF="26_glo_o.htm#output"><I>output</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>streams</I></A> such that any output sent to the <A REL=DEFINITION HREF="26_glo_b.htm#broadcast_stream"><I>broadcast stream</I></A> gets passed on as output to each of the associated <A REL=DEFINITION HREF="26_glo_o.htm#output"><I>output</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>streams</I></A>. (If a <A REL=DEFINITION HREF="26_glo_b.htm#broadcast_stream"><I>broadcast stream</I></A> has no <I>component streams</I>, then all output to the <A REL=DEFINITION HREF="26_glo_b.htm#broadcast_stream"><I>broadcast stream</I></A> is discarded.) <P>
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The set of operations that may be performed on a <A REL=DEFINITION HREF="26_glo_b.htm#broadcast_stream"><I>broadcast stream</I></A> is the intersection of those for its associated <A REL=DEFINITION HREF="26_glo_o.htm#output"><I>output</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>streams</I></A>. <P>
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Some output operations (e.g., <A REL=DEFINITION HREF="f_terpri.htm#fresh-line"><B>fresh-line</B></A>) return <A REL=DEFINITION HREF="26_glo_v.htm#value"><I>values</I></A> based on the state of the <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>stream</I></A> at the time of the operation. Since these <A REL=DEFINITION HREF="26_glo_v.htm#value"><I>values</I></A> might differ for each of the <I>component streams</I>, it is necessary to describe their return value specifically: <P>
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<P><DL><P>
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<DT>* <A REL=DEFINITION HREF="f_stm_el.htm#stream-element-type"><B>stream-element-type</B></A> returns the value from the last component stream, or <A REL=DEFINITION HREF="t_t.htm#t"><B>t</B></A> if there are no component streams. <P><DD>
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<DT>* <A REL=DEFINITION HREF="f_terpri.htm#fresh-line"><B>fresh-line</B></A> returns the value from the last component stream, or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> if there are no component streams. <P><DD>
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<DT>* The functions <A REL=DEFINITION HREF="f_file_l.htm#file-length"><B>file-length</B></A>, <A REL=DEFINITION HREF="f_file_p.htm#file-position"><B>file-position</B></A>, <A REL=DEFINITION HREF="f_file_s.htm#file-string-length"><B>file-string-length</B></A>, and <A REL=DEFINITION HREF="f_stm_ex.htm#stream-external-format"><B>stream-external-format</B></A> return the value from the last component stream; if there are no component streams, <A REL=DEFINITION HREF="f_file_l.htm#file-length"><B>file-length</B></A> and <A REL=DEFINITION HREF="f_file_p.htm#file-position"><B>file-position</B></A> return <TT>0</TT>, <A REL=DEFINITION HREF="f_file_s.htm#file-string-length"><B>file-string-length</B></A> returns <TT>1</TT>, and <A REL=DEFINITION HREF="f_stm_ex.htm#stream-external-format"><B>stream-external-format</B></A> returns <TT>:default</TT>. <P><DD>
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<DT>* The functions <A REL=DEFINITION HREF="f_stmp.htm#streamp"><B>streamp</B></A> and <A REL=DEFINITION HREF="f_in_stm.htm#output-stream-p"><B>output-stream-p</B></A> always return <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A> for <A REL=DEFINITION HREF="26_glo_b.htm#broadcast_stream"><I>broadcast streams</I></A>. <P><DD>
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<DT>* The functions <A REL=DEFINITION HREF="f_open_s.htm#open-stream-p"><B>open-stream-p</B></A> tests whether the <A REL=DEFINITION HREF="26_glo_b.htm#broadcast_stream"><I>broadcast stream</I></A> is <A REL=DEFINITION HREF="26_glo_o.htm#open"><I>open</I></A>[2], not whether its component streams are <A REL=DEFINITION HREF="26_glo_o.htm#open"><I>open</I></A>. <P><DD>
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<DT>* The functions <A REL=DEFINITION HREF="f_in_stm.htm#input-stream-p"><B>input-stream-p</B></A> and <A REL=DEFINITION HREF="f_intera.htm#interactive-stream-p"><I>interactive-stream-p</I></A> return an <A REL=DEFINITION HREF="26_glo_i.htm#implementation-defined"><I>implementation-defined</I></A>, <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A> value. <P><DD>
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<DT>* For the input operations <A REL=DEFINITION HREF="f_clear_.htm#clear-input"><B>clear-input</B></A> <A REL=DEFINITION HREF="f_listen.htm#listen"><B>listen</B></A>, <A REL=DEFINITION HREF="f_peek_c.htm#peek-char"><B>peek-char</B></A>, <A REL=DEFINITION HREF="f_rd_by.htm#read-byte"><B>read-byte</B></A>, <A REL=DEFINITION HREF="f_rd_c_1.htm#read-char-no-hang"><B>read-char-no-hang</B></A>, <A REL=DEFINITION HREF="f_rd_cha.htm#read-char"><B>read-char</B></A>, <A REL=DEFINITION HREF="f_rd_lin.htm#read-line"><B>read-line</B></A>, and <A REL=DEFINITION HREF="f_unrd_c.htm#unread-char"><B>unread-char</B></A>, the consequences are undefined if the indicated operation is performed. However, an <A REL=DEFINITION HREF="26_glo_i.htm#implementation"><I>implementation</I></A> is permitted to define such a behavior as an <A REL=DEFINITION HREF="26_glo_i.htm#implementation-dependent"><I>implementation-dependent</I></A> extension. <P><DD></DL><P>
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For any output operations not having their return values explicitly specified above or elsewhere in this document, it is defined that the <A REL=DEFINITION HREF="26_glo_v.htm#value"><I>values</I></A> returned by such an operation are the <A REL=DEFINITION HREF="26_glo_v.htm#value"><I>values</I></A> resulting from performing the operation on the last of its <I>component streams</I>; the <A REL=DEFINITION HREF="26_glo_v.htm#value"><I>values</I></A> resulting from performing the operation on all preceding <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>streams</I></A> are discarded. If there are no <I>component streams</I>, the value is <A REL=DEFINITION HREF="26_glo_i.htm#implementation-dependent"><I>implementation-dependent</I></A>. <P>
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<P><B>See Also:</B><P>
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<P>
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<A REL=DEFINITION HREF="f_broadc.htm#broadcast-stream-streams"><B>broadcast-stream-streams</B></A>, <A REL=DEFINITION HREF="f_mk_bro.htm#make-broadcast-stream"><B>make-broadcast-stream</B></A> <P>
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<P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issues</A>, <I>not part of the specification</I>, apply to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss021.htm">BROADCAST-STREAM-RETURN-VALUES:CLARIFY-MINIMALLY</A><LI> <A REL=CHILD HREF="../Issues/iss327.htm">STREAM-ACCESS:ADD-TYPES-ACCESSORS</A><LI> <A REL=CHILD HREF="../Issues/iss351.htm">TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND</A><P></UL><HR>
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