toolchain/share/doc/gdb/Pretty_002dPrinter-Introduc...

90 lines
4.2 KiB
HTML

<html lang="en">
<head>
<title>Pretty-Printer Introduction - Debugging with GDB</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="Debugging with GDB">
<meta name="generator" content="makeinfo 4.13">
<link title="Top" rel="start" href="index.html#Top">
<link rel="up" href="Pretty-Printing.html#Pretty-Printing" title="Pretty Printing">
<link rel="next" href="Pretty_002dPrinter-Example.html#Pretty_002dPrinter-Example" title="Pretty-Printer Example">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<!--
Copyright (C) 1988-2019 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 the
Invariant Sections being ``Free Software'' and ``Free Software Needs
Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,''
and with the Back-Cover Texts as in (a) below.
(a) The FSF's Back-Cover Text is: ``You are free to copy and modify
this GNU Manual. Buying copies from GNU Press supports the FSF in
developing GNU and promoting software freedom.''
-->
<meta http-equiv="Content-Style-Type" content="text/css">
<style type="text/css"><!--
pre.display { font-family:inherit }
pre.format { font-family:inherit }
pre.smalldisplay { font-family:inherit; font-size:smaller }
pre.smallformat { font-family:inherit; font-size:smaller }
pre.smallexample { font-size:smaller }
pre.smalllisp { font-size:smaller }
span.sc { font-variant:small-caps }
span.roman { font-family:serif; font-weight:normal; }
span.sansserif { font-family:sans-serif; font-weight:normal; }
--></style>
</head>
<body>
<div class="node">
<a name="Pretty-Printer-Introduction"></a>
<a name="Pretty_002dPrinter-Introduction"></a>
<p>
Next:&nbsp;<a rel="next" accesskey="n" href="Pretty_002dPrinter-Example.html#Pretty_002dPrinter-Example">Pretty-Printer Example</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="Pretty-Printing.html#Pretty-Printing">Pretty Printing</a>
<hr>
</div>
<h4 class="subsection">10.9.1 Pretty-Printer Introduction</h4>
<p>When <span class="sc">gdb</span> prints a value, it first sees if there is a pretty-printer
registered for the value. If there is then <span class="sc">gdb</span> invokes the
pretty-printer to print the value. Otherwise the value is printed normally.
<p>Pretty-printers are normally named. This makes them easy to manage.
The &lsquo;<samp><span class="samp">info pretty-printer</span></samp>&rsquo; command will list all the installed
pretty-printers with their names.
If a pretty-printer can handle multiple data types, then its
<dfn>subprinters</dfn> are the printers for the individual data types.
Each such subprinter has its own name.
The format of the name is <var>printer-name</var>;<var>subprinter-name</var>.
<p>Pretty-printers are installed by <dfn>registering</dfn> them with <span class="sc">gdb</span>.
Typically they are automatically loaded and registered when the corresponding
debug information is loaded, thus making them available without having to
do anything special.
<p>There are three places where a pretty-printer can be registered.
<ul>
<li>Pretty-printers registered globally are available when debugging
all inferiors.
<li>Pretty-printers registered with a program space are available only
when debugging that program.
See <a href="Progspaces-In-Python.html#Progspaces-In-Python">Progspaces In Python</a>, for more details on program spaces in Python.
<li>Pretty-printers registered with an objfile are loaded and unloaded
with the corresponding objfile (e.g., shared library).
See <a href="Objfiles-In-Python.html#Objfiles-In-Python">Objfiles In Python</a>, for more details on objfiles in Python.
</ul>
<p>See <a href="Selecting-Pretty_002dPrinters.html#Selecting-Pretty_002dPrinters">Selecting Pretty-Printers</a>, for further information on how
pretty-printers are selected,
<p>See <a href="Writing-a-Pretty_002dPrinter.html#Writing-a-Pretty_002dPrinter">Writing a Pretty-Printer</a>, for implementing pretty printers
for new types.
</body></html>