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DEC-10 compatibility input/output
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<H3 CLASS="subsection"><A NAME="htoc171">7.16</A> DEC-10 compatibility input/output</H3><UL>
<LI><A HREF="gprolog039.html#toc134">Introduction</A>
<LI><A HREF="gprolog039.html#toc135"><TT>see/1</TT>,
<TT>tell/1</TT>,
<TT>append/1</TT></A>
<LI><A HREF="gprolog039.html#toc136"><TT>seeing/1</TT>,
<TT>telling/1</TT></A>
<LI><A HREF="gprolog039.html#toc137"><TT>seen/0</TT>,
<TT>told/0</TT></A>
<LI><A HREF="gprolog039.html#toc138"><TT>get0/1</TT>,
<TT>get/1</TT>,
<TT>skip/1</TT></A>
<LI><A HREF="gprolog039.html#toc139"><TT>put/1</TT>,
<TT>tab/1</TT></A>
</UL>
<A NAME="toc134"></A>
<H4 CLASS="subsubsection"><A NAME="htoc172">7.16.1</A> Introduction</H4>
The DEC-10 Prolog I/O predicates manipulate streams implicitly since they
only refer to current input/output streams (section <A HREF="gprolog033.html#Introduction:(Streams)">7.10.1</A>).
The current input and output streams are initially set to
<TT>user_input</TT> and <TT>user_output</TT> respectively. The predicate
<TT>see/1</TT>
(resp. <TT>tell/1</TT>, <TT>append/1</TT>) can be used for setting the
current input (resp. output) stream to newly opened streams for
particular files. The predicate <TT>seen/0</TT>
(resp. <TT>told/0</TT>) close the current input (resp. output) stream,
and resets it to the standard input (resp. output). The predicate
<TT>seeing/1</TT> (resp. <TT>telling/1</TT>) is used for retrieving
the file name associated with the current input (resp. output)
stream. The file name <TT>user</TT> stands for the standard input or
output, depending on context (<TT>user_input</TT> and
<TT>user_output</TT> can also be used). The DEC-10 Prolog I/O predicates
are only provided for compatibility, they are now obsolete and
their use is discouraged. The predicates for explicit stream manipulation
should be used instead (section <A HREF="gprolog033.html#Streams">7.10</A>).<BR>
<BR>
<A NAME="toc135"></A>
<H4 CLASS="subsubsection"><A NAME="htoc173">7.16.2</A> <TT>see/1</TT>,
<TT>tell/1</TT>,
<TT>append/1</TT></H4>
<B>Templates</B>
<DL CLASS="list" COMPACT="compact"><DT CLASS="dt-list"><DD CLASS="dd-list"><TT>
see(+source_sink)<BR>
see(+stream)<BR>
tell(+source_sink)<BR>
tell(+stream)<BR>
append(+source_sink)<BR>
append(+stream)</TT></DL>
<B>Description</B><BR>
<BR>
<TT>see(FileName)</TT> sets the current input stream to <TT>FileName</TT>.
If there is a stream opened by <TT>see/1</TT> associated with the same
<TT>FileName</TT> already, then it becomes the current input stream.
Otherwise, <TT>FileName</TT> is opened for reading and becomes the current
input stream.<BR>
<BR>
<TT>tell(FileName)</TT> sets the current output stream to <TT>FileName</TT>.
If there is a stream opened by <TT>tell/1</TT> associated with the same
<TT>FileName</TT> already, then it becomes the current output stream.
Otherwise, <TT>FileName</TT> is opened for writing and becomes the current
output stream.<BR>
<BR>
<TT>append(FileName)</TT> like <TT>tell/1</TT> but
<TT>FileName</TT> is opened for writing + append.<BR>
<BR>
A stream-term (obtained with any other built-in predicate) can also be
provided as <TT>FileName</TT> to these predicates.<BR>
<BR>
<B>Errors</B><BR>
<BR>
See errors associated with <TT>open/4</TT> (section <A HREF="gprolog033.html#open/4">7.10.6</A>).<BR>
<BR>
<B>Portability</B><BR>
<BR>
GNU Prolog predicates.<BR>
<BR>
<A NAME="toc136"></A>
<H4 CLASS="subsubsection"><A NAME="htoc174">7.16.3</A> <TT>seeing/1</TT>,
<TT>telling/1</TT></H4>
<B>Templates</B>
<DL CLASS="list" COMPACT="compact"><DT CLASS="dt-list"><DD CLASS="dd-list"><TT>
seeing(?source_sink)<BR>
telling(?source_sink)</TT></DL>
<B>Description</B><BR>
<BR>
<TT>seeing(FileName)</TT> succeeds if <TT>FileName</TT> unifies
with the name of the current input file, if it was opened by
<TT>see/1</TT>; else with the current input stream-term, if this is not
<TT>user_input</TT>, otherwise with
<TT>user</TT>. <BR>
<BR>
<TT>telling(FileName)</TT> succeeds if <TT>FileName</TT> unifies with the
name of the current output file, if it was opened by <TT>tell/1</TT> or
<TT>append/1</TT>; else with the current output stream-term, if this is not
<TT>user_output</TT>, otherwise with <TT>user</TT>. <BR>
<BR>
<B>Errors</B><BR>
<BR>
None.<BR>
<BR>
<B>Portability</B><BR>
<BR>
GNU Prolog predicates.<BR>
<BR>
<A NAME="toc137"></A>
<H4 CLASS="subsubsection"><A NAME="htoc175">7.16.4</A> <TT>seen/0</TT>,
<TT>told/0</TT></H4>
<B>Templates</B>
<DL CLASS="list" COMPACT="compact"><DT CLASS="dt-list"><DD CLASS="dd-list"><TT>
seen<BR>
told</TT></DL>
<B>Description</B><BR>
<BR>
<TT>seen</TT> closes the current input, and resets it to
<TT>user_input</TT>.<BR>
<BR>
<TT>told</TT> closes the current output, and resets it to
<TT>user_output</TT>.<BR>
<BR>
<B>Errors</B><BR>
<BR>
None.<BR>
<BR>
<B>Portability</B><BR>
<BR>
GNU Prolog predicates.<BR>
<BR>
<A NAME="toc138"></A>
<H4 CLASS="subsubsection"><A NAME="htoc176">7.16.5</A> <TT>get0/1</TT>,
<TT>get/1</TT>,
<TT>skip/1</TT></H4>
<B>Templates</B>
<DL CLASS="list" COMPACT="compact"><DT CLASS="dt-list"><DD CLASS="dd-list"><TT>
get0(?in_character_code)<BR>
get(?in_character_code)<BR>
skip(+character_code)</TT></DL>
<B>Description</B><BR>
<BR>
<TT>get0(Code)</TT> succeeds if <TT>Code</TT> unifies with the next
character code read from the current input stream. Thus it is equivalent to
<TT>get_code(Code)</TT> (section <A HREF="gprolog035.html#get-char/2">7.12.1</A>).<BR>
<BR>
<TT>get(Code)</TT> succeeds if <TT>Code</TT> unifies with the next character
code read from the current input stream that is not a layout character.<BR>
<BR>
<TT>skip(Code)</TT> skips just past the next character code <TT>Code</TT>
from the current input stream.<BR>
<BR>
<B>Errors</B><BR>
<BR>
See errors for <TT>get_code/2</TT> (section <A HREF="gprolog035.html#get-char/2">7.12.1</A>).<BR>
<BR>
<B>Portability</B><BR>
<BR>
GNU Prolog predicates.<BR>
<BR>
<A NAME="toc139"></A>
<H4 CLASS="subsubsection"><A NAME="htoc177">7.16.6</A> <TT>put/1</TT>,
<TT>tab/1</TT></H4>
<B>Templates</B>
<DL CLASS="list" COMPACT="compact"><DT CLASS="dt-list"><DD CLASS="dd-list"><TT>
put(+character_code)<BR>
tab(+evaluable)</TT></DL>
<B>Description</B><BR>
<BR>
<TT>put(Code)</TT> writes the character whose code is <TT>Code</TT> onto the
current output stream. It is equivalent to <TT>put_code(Code)</TT>
(section <A HREF="gprolog035.html#put-char/2">7.12.5</A>).<BR>
<BR>
<TT>tab(N)</TT> writes <TT>N</TT> spaces onto the current output
stream. <TT>N</TT> may be an arithmetic expression.<BR>
<BR>
<B>Errors</B><BR>
<BR>
See errors for <TT>put_code/2</TT> (section <A HREF="gprolog035.html#put-char/2">7.12.5</A>) and for arithmetic
expressions (section <A HREF="gprolog029.html#Evaluation-of-an-arithmetic-expression">7.6.1</A>).<BR>
<BR>
<B>Portability</B><BR>
<BR>
GNU Prolog predicates.<BR>
<BR>
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Copyright (C) 1999-2007 Daniel Diaz
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