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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:44:05 +0000 |
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| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:44:05 +0000 |
| commit | d318611dd6f23fcfedd50e9b9e24620b102ba96a (patch) | |
| tree | 8b9eef82ca40fdd5a8deeabf07572074c236095d /doc/groff.html.node/End_002dof_002dinput-Traps.html | |
| parent | Initial commit. (diff) | |
| download | groff-upstream/1.23.0.tar.xz groff-upstream/1.23.0.zip | |
Adding upstream version 1.23.0.upstream/1.23.0upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
| -rw-r--r-- | doc/groff.html.node/End_002dof_002dinput-Traps.html | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/doc/groff.html.node/End_002dof_002dinput-Traps.html b/doc/groff.html.node/End_002dof_002dinput-Traps.html new file mode 100644 index 0000000..4dad1f2 --- /dev/null +++ b/doc/groff.html.node/End_002dof_002dinput-Traps.html @@ -0,0 +1,187 @@ +<!DOCTYPE html> +<html> +<!-- Created by GNU Texinfo 7.0.3, https://www.gnu.org/software/texinfo/ --> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> +<!-- This manual documents GNU troff version 1.23.0. + +Copyright © 1994-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with no +Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A +copy of the license is included in the section entitled "GNU Free +Documentation License". --> +<title>End-of-input Traps (The GNU Troff Manual)</title> + +<meta name="description" content="End-of-input Traps (The GNU Troff Manual)"> +<meta name="keywords" content="End-of-input Traps (The GNU Troff Manual)"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta name="viewport" content="width=device-width,initial-scale=1"> + +<link href="index.html" rel="start" title="Top"> +<link href="Request-Index.html" rel="index" title="Request Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Traps.html" rel="up" title="Traps"> +<link href="Leading-Space-Traps.html" rel="prev" title="Leading Space Traps"> +<style type="text/css"> +<!-- +a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em} +div.example {margin-left: 3.2em} +span.r {font-family: initial; font-weight: normal; font-style: normal} +span:hover a.copiable-link {visibility: visible} +strong.def-name {font-family: monospace; font-weight: bold; font-size: larger} +--> +</style> + + +</head> + +<body lang="en"> +<div class="subsection-level-extent" id="End_002dof_002dinput-Traps"> +<div class="nav-panel"> +<p> +Previous: <a href="Leading-Space-Traps.html" accesskey="p" rel="prev">Leading Space Traps</a>, Up: <a href="Traps.html" accesskey="u" rel="up">Traps</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Request-Index.html" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<h4 class="subsection" id="End_002dof_002dinput-Traps-1">5.28.5 End-of-input Traps</h4> +<a class="index-entry-id" id="index-end_002dof_002dinput-traps"></a> +<a class="index-entry-id" id="index-traps_002c-end_002dof_002dinput"></a> + +<dl class="first-deffn"> +<dt class="deffn" id="index-_002eem"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.em</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002eem'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-em"></a> +<a class="index-entry-id" id="index-setting-end_002dof_002dinput-trap-_0028em_0029"></a> +<a class="index-entry-id" id="index-end_002dof_002dinput-trap_002c-setting-_0028em_0029"></a> +<a class="index-entry-id" id="index-trap_002c-end_002dof_002dinput_002c-setting-_0028em_0029"></a> +<a class="index-entry-id" id="index-end_002dof_002dinput-macro-_0028em_0029"></a> +<a class="index-entry-id" id="index-macro_002c-end_002dof_002dinput-_0028em_0029"></a> +<p>Set a trap at the end of input, calling macro <var class="var">name</var> after the last +line of the last input file has been processed. If no argument is +given, any existing end-of-input trap is removed. +</p> +<p>For example, if the document had to have a section at the bottom of the +last page for someone to approve it, the <code class="code">em</code> request could be +used. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">.de approval +\c +. ne 3v +. sp (\\n[.t]u - 3v) +. in +4i +. lc _ +. br +Approved:\t\a +. sp +Date:\t\t\a +.. +. +.em approval +</pre></div></div> + +<p>The <code class="code">\c</code> in the above example needs explanation. For historical +reasons (compatibility with <abbr class="acronym">AT&T</abbr> <code class="code">troff</code>), the +end-of-input macro exits as soon as it causes a page break if no +partially collected line remains.<a class="footnote" id="DOCF111" href="groff.html_fot.html#FOOT111"><sup>111</sup></a> +</p> +<a class="index-entry-id" id="index-page-break_002c-final"></a> +<a class="index-entry-id" id="index-break_002c-page_002c-final"></a> +<a class="index-entry-id" id="index-page-ejection_002c-of-final-page"></a> +<a class="index-entry-id" id="index-ejection_002c-page_002c-of-final-page"></a> +<p>Let us assume that there is no <code class="code">\c</code> in the above <code class="code">approval</code> +macro, that the page is full, and last output line has been broken with, +say, a <code class="code">br</code> request. Because there is no more room, a <code class="code">ne</code> +request at this point causes a page ejection, which in turn makes +<code class="code">troff</code> exit immediately as just described. In most situations, +this is not desired; people generally want to format the input after +<code class="code">ne</code>. +</p> +<p>To force processing of the whole end-of-input macro independently of +this behavior, it is thus advisable to (invisibly) ensure the existence +of a partially collected line (<code class="code">\c</code>) whenever there is a chance +that a page break can happen. In the above example, invoking the +<code class="code">ne</code> request ensures that there is room for the subsequent +formatted output on the same page, so we need insert <code class="code">\c</code> only +once. +</p> +<p>The next example shows how to append three lines, then start a new page +unconditionally. Since ‘<samp class="samp">.ne 1</samp>’<!-- /@w --> doesn’t give the desired +effect—there is always one line available or we are already at the +beginning of the next page—we temporarily increase the page length by +one line so that we can use ‘<samp class="samp">.ne 2</samp>’<!-- /@w -->. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">.de EM +.pl +1v +\c +.ne 2 +line one +.br +\c +.ne 2 +line two +.br +\c +.ne 2 +line three +.br +.pl -1v +\c +'bp +.. +.em EM +</pre></div></div> + +<p>This specific feature affects only the first potential page break caused +by the end-of-input macro; further page breaks emitted by the macro are +handled normally. +</p> +<p>Another possible use of the <code class="code">em</code> request is to make GNU +<code class="code">troff</code> emit a single large page instead of multiple pages. For +example, one may want to produce a long plain text file for reading +in a terminal or emulator without page footers and headers interrupting +the body of the document. One approach is to set the page length at the +beginning of the document to a very large value to hold all the +text,<a class="footnote" id="DOCF112" href="groff.html_fot.html#FOOT112"><sup>112</sup></a> and +automatically adjust it to the exact height of the document after the +text has been output. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">.de adjust-page-length +. br +. pl \\n[nl]u \" \n[nl]: current vertical position +.. +. +.de single-page-mode +. pl 99999 +. em adjust-page-length +.. +. +.\" Activate the above code if configured. +.if \n[do-continuous-rendering] \ +. single-page-mode +</pre></div></div> + +<p>Since only one end-of-input trap exists and another macro package may +already use it, care must be taken not to break the mechanism. A simple +solution would be to append the above macro to the macro package’s +end-of-input macro using the <code class="code">am</code> request. +</p></dd></dl> + + + +</div> +<hr> +<div class="nav-panel"> +<p> +Previous: <a href="Leading-Space-Traps.html">Leading Space Traps</a>, Up: <a href="Traps.html">Traps</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Request-Index.html" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |