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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gdb/Xmethods-In-Python.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
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diff --git a/share/doc/gdb/Xmethods-In-Python.html b/share/doc/gdb/Xmethods-In-Python.html new file mode 100644 index 0000000..e92f26f --- /dev/null +++ b/share/doc/gdb/Xmethods-In-Python.html @@ -0,0 +1,131 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 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 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." --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>Debugging with GDB: Xmethods In Python</title> + +<meta name="description" content="Debugging with GDB: Xmethods In Python"> +<meta name="keywords" content="Debugging with GDB: Xmethods In Python"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Python-API.html#Python-API" rel="up" title="Python API"> +<link href="Xmethod-API.html#Xmethod-API" rel="next" title="Xmethod API"> +<link href="Unwinding-Frames-in-Python.html#Unwinding-Frames-in-Python" rel="previous" title="Unwinding Frames in Python"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Xmethods-In-Python"></a> +<div class="header"> +<p> +Next: <a href="Xmethod-API.html#Xmethod-API" accesskey="n" rel="next">Xmethod API</a>, Previous: <a href="Unwinding-Frames-in-Python.html#Unwinding-Frames-in-Python" accesskey="p" rel="previous">Unwinding Frames in Python</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Xmethods-In-Python-1"></a> +<h4 class="subsubsection">23.3.2.13 Xmethods In Python</h4> +<a name="index-xmethods-in-Python"></a> + +<p><em>Xmethods</em> are additional methods or replacements for existing +methods of a C<tt>++</tt> class. This feature is useful for those cases +where a method defined in C<tt>++</tt> source code could be inlined or +optimized out by the compiler, making it unavailable to <small>GDB</small>. +For such cases, one can define an xmethod to serve as a replacement +for the method defined in the C<tt>++</tt> source code. <small>GDB</small> will +then invoke the xmethod, instead of the C<tt>++</tt> method, to +evaluate expressions. One can also use xmethods when debugging +with core files. Moreover, when debugging live programs, invoking an +xmethod need not involve running the inferior (which can potentially +perturb its state). Hence, even if the C<tt>++</tt> method is available, it +is better to use its replacement xmethod if one is defined. +</p> +<p>The xmethods feature in Python is available via the concepts of an +<em>xmethod matcher</em> and an <em>xmethod worker</em>. To +implement an xmethod, one has to implement a matcher and a +corresponding worker for it (more than one worker can be +implemented, each catering to a different overloaded instance of the +method). Internally, <small>GDB</small> invokes the <code>match</code> method of a +matcher to match the class type and method name. On a match, the +<code>match</code> method returns a list of matching <em>worker</em> objects. +Each worker object typically corresponds to an overloaded instance of +the xmethod. They implement a <code>get_arg_types</code> method which +returns a sequence of types corresponding to the arguments the xmethod +requires. <small>GDB</small> uses this sequence of types to perform +overload resolution and picks a winning xmethod worker. A winner +is also selected from among the methods <small>GDB</small> finds in the +C<tt>++</tt> source code. Next, the winning xmethod worker and the +winning C<tt>++</tt> method are compared to select an overall winner. In +case of a tie between a xmethod worker and a C<tt>++</tt> method, the +xmethod worker is selected as the winner. That is, if a winning +xmethod worker is found to be equivalent to the winning C<tt>++</tt> +method, then the xmethod worker is treated as a replacement for +the C<tt>++</tt> method. <small>GDB</small> uses the overall winner to invoke the +method. If the winning xmethod worker is the overall winner, then +the corresponding xmethod is invoked via the <code>__call__</code> method +of the worker object. +</p> +<p>If one wants to implement an xmethod as a replacement for an +existing C<tt>++</tt> method, then they have to implement an equivalent +xmethod which has exactly the same name and takes arguments of +exactly the same type as the C<tt>++</tt> method. If the user wants to +invoke the C<tt>++</tt> method even though a replacement xmethod is +available for that method, then they can disable the xmethod. +</p> +<p>See <a href="Xmethod-API.html#Xmethod-API">Xmethod API</a>, for API to implement xmethods in Python. +See <a href="Writing-an-Xmethod.html#Writing-an-Xmethod">Writing an Xmethod</a>, for implementing xmethods in Python. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="Xmethod-API.html#Xmethod-API" accesskey="n" rel="next">Xmethod API</a>, Previous: <a href="Unwinding-Frames-in-Python.html#Unwinding-Frames-in-Python" accesskey="p" rel="previous">Unwinding Frames in Python</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |