aarch64-linux-gnu-4.9/share/doc/gdb/gdb/Symbols-In-Python.html - toolchains/linux-x86/gcc - Git at Google

 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 <html>
 <!-- Copyright (C) 1988-2015 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 5.2, http://www.gnu.org/software/texinfo/ -->
 <head>
 <title>Debugging with GDB: Symbols In Python</title>

 <meta name="description" content="Debugging with GDB: Symbols In Python">
 <meta name="keywords" content="Debugging with GDB: Symbols 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="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python" rel="next" title="Symbol Tables In Python">
 <link href="Blocks-In-Python.html#Blocks-In-Python" rel="prev" title="Blocks 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="Symbols-In-Python"></a>
 <div class="header">
 <p>
 Next: <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python" accesskey="n" rel="next">Symbol Tables In Python</a>, Previous: <a href="Blocks-In-Python.html#Blocks-In-Python" accesskey="p" rel="prev">Blocks In Python</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> &nbsp; [<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="Python-representation-of-Symbols_002e"></a>
 <h4 class="subsubsection">23.2.2.26 Python representation of Symbols.</h4>

 <a name="index-symbols-in-python"></a>
 <a name="index-gdb_002eSymbol"></a>

 <p><small>GDB</small> represents every variable, function and type as an
 entry in a symbol table.  See <a href="Symbols.html#Symbols">Examining the Symbol Table</a>.
 Similarly, Python represents these symbols in <small>GDB</small> with the
 <code>gdb.Symbol</code> object.
 </p>
 <p>The following symbol-related functions are available in the <code>gdb</code>
 module:
 </p>
 <a name="index-gdb_002elookup_005fsymbol"></a>
 <dl>
 <dt><a name="index-gdb_002elookup_005fsymbol-1"></a>Function: <strong>gdb.lookup_symbol</strong> <em>(name <span class="roman">[</span>, block <span class="roman">[</span>, domain<span class="roman">]]</span>)</em></dt>
 <dd><p>This function searches for a symbol by name.  The search scope can be
 restricted to the parameters defined in the optional domain and block
 arguments.
 </p>
 <p><var>name</var> is the name of the symbol.  It must be a string.  The
 optional <var>block</var> argument restricts the search to symbols visible
 in that <var>block</var>.  The <var>block</var> argument must be a
 <code>gdb.Block</code> object.  If omitted, the block for the current frame
 is used.  The optional <var>domain</var> argument restricts
 the search to the domain type.  The <var>domain</var> argument must be a
 domain constant defined in the <code>gdb</code> module and described later
 in this chapter.
 </p>
 <p>The result is a tuple of two elements.
 The first element is a <code>gdb.Symbol</code> object or <code>None</code> if the symbol
 is not found.
 If the symbol is found, the second element is <code>True</code> if the symbol
 is a field of a method&rsquo;s object (e.g., <code>this</code> in C<tt>++</tt>),
 otherwise it is <code>False</code>.
 If the symbol is not found, the second element is <code>False</code>.
 </p></dd></dl>

 <a name="index-gdb_002elookup_005fglobal_005fsymbol"></a>
 <dl>
 <dt><a name="index-gdb_002elookup_005fglobal_005fsymbol-1"></a>Function: <strong>gdb.lookup_global_symbol</strong> <em>(name <span class="roman">[</span>, domain<span class="roman">]</span>)</em></dt>
 <dd><p>This function searches for a global symbol by name.
 The search scope can be restricted to by the domain argument.
 </p>
 <p><var>name</var> is the name of the symbol.  It must be a string.
 The optional <var>domain</var> argument restricts the search to the domain type.
 The <var>domain</var> argument must be a domain constant defined in the <code>gdb</code>
 module and described later in this chapter.
 </p>
 <p>The result is a <code>gdb.Symbol</code> object or <code>None</code> if the symbol
 is not found.
 </p></dd></dl>

 <p>A <code>gdb.Symbol</code> object has the following attributes:
 </p>
 <dl>
 <dt><a name="index-Symbol_002etype"></a>Variable: <strong>Symbol.type</strong></dt>
 <dd><p>The type of the symbol or <code>None</code> if no type is recorded.
 This attribute is represented as a <code>gdb.Type</code> object.
 See <a href="Types-In-Python.html#Types-In-Python">Types In Python</a>.  This attribute is not writable.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002esymtab"></a>Variable: <strong>Symbol.symtab</strong></dt>
 <dd><p>The symbol table in which the symbol appears.  This attribute is
 represented as a <code>gdb.Symtab</code> object.  See <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python">Symbol Tables In Python</a>.  This attribute is not writable.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002eline"></a>Variable: <strong>Symbol.line</strong></dt>
 <dd><p>The line number in the source code at which the symbol was defined.
 This is an integer.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002ename"></a>Variable: <strong>Symbol.name</strong></dt>
 <dd><p>The name of the symbol as a string.  This attribute is not writable.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002elinkage_005fname"></a>Variable: <strong>Symbol.linkage_name</strong></dt>
 <dd><p>The name of the symbol, as used by the linker (i.e., may be mangled).
 This attribute is not writable.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002eprint_005fname"></a>Variable: <strong>Symbol.print_name</strong></dt>
 <dd><p>The name of the symbol in a form suitable for output.  This is either
 <code>name</code> or <code>linkage_name</code>, depending on whether the user
 asked <small>GDB</small> to display demangled or mangled names.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002eaddr_005fclass"></a>Variable: <strong>Symbol.addr_class</strong></dt>
 <dd><p>The address class of the symbol.  This classifies how to find the value
 of a symbol.  Each address class is a constant defined in the
 <code>gdb</code> module and described later in this chapter.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002eneeds_005fframe"></a>Variable: <strong>Symbol.needs_frame</strong></dt>
 <dd><p>This is <code>True</code> if evaluating this symbol&rsquo;s value requires a frame
 (see <a href="Frames-In-Python.html#Frames-In-Python">Frames In Python</a>) and <code>False</code> otherwise.  Typically,
 local variables will require a frame, but other symbols will not.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002eis_005fargument"></a>Variable: <strong>Symbol.is_argument</strong></dt>
 <dd><p><code>True</code> if the symbol is an argument of a function.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002eis_005fconstant"></a>Variable: <strong>Symbol.is_constant</strong></dt>
 <dd><p><code>True</code> if the symbol is a constant.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002eis_005ffunction"></a>Variable: <strong>Symbol.is_function</strong></dt>
 <dd><p><code>True</code> if the symbol is a function or a method.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002eis_005fvariable"></a>Variable: <strong>Symbol.is_variable</strong></dt>
 <dd><p><code>True</code> if the symbol is a variable.
 </p></dd></dl>

 <p>A <code>gdb.Symbol</code> object has the following methods:
 </p>
 <dl>
 <dt><a name="index-Symbol_002eis_005fvalid"></a>Function: <strong>Symbol.is_valid</strong> <em>()</em></dt>
 <dd><p>Returns <code>True</code> if the <code>gdb.Symbol</code> object is valid,
 <code>False</code> if not.  A <code>gdb.Symbol</code> object can become invalid if
 the symbol it refers to does not exist in <small>GDB</small> any longer.
 All other <code>gdb.Symbol</code> methods will throw an exception if it is
 invalid at the time the method is called.
 </p></dd></dl>

 <dl>
 <dt><a name="index-Symbol_002evalue"></a>Function: <strong>Symbol.value</strong> <em>(<span class="roman">[</span>frame<span class="roman">]</span>)</em></dt>
 <dd><p>Compute the value of the symbol, as a <code>gdb.Value</code>.  For
 functions, this computes the address of the function, cast to the
 appropriate type.  If the symbol requires a frame in order to compute
 its value, then <var>frame</var> must be given.  If <var>frame</var> is not
 given, or if <var>frame</var> is invalid, then this method will throw an
 exception.
 </p></dd></dl>

 <p>The available domain categories in <code>gdb.Symbol</code> are represented
 as constants in the <code>gdb</code> module:
 </p>
 <dl compact="compact">
 <dd><a name="index-SYMBOL_005fUNDEF_005fDOMAIN"></a>
 </dd>
 <dt><code>gdb.SYMBOL_UNDEF_DOMAIN</code>
 <a name="index-gdb_002eSYMBOL_005fUNDEF_005fDOMAIN"></a>
 </dt>
 <dd><p>This is used when a domain has not been discovered or none of the
 following domains apply.  This usually indicates an error either
 in the symbol information or in <small>GDB</small>&rsquo;s handling of symbols.
 </p>
 <a name="index-SYMBOL_005fVAR_005fDOMAIN"></a>
 </dd>
 <dt><code>gdb.SYMBOL_VAR_DOMAIN</code>
 <a name="index-gdb_002eSYMBOL_005fVAR_005fDOMAIN"></a>
 </dt>
 <dd><p>This domain contains variables, function names, typedef names and enum
 type values.
 </p>
 <a name="index-SYMBOL_005fSTRUCT_005fDOMAIN"></a>
 </dd>
 <dt><code>gdb.SYMBOL_STRUCT_DOMAIN</code>
 <a name="index-gdb_002eSYMBOL_005fSTRUCT_005fDOMAIN"></a>
 </dt>
 <dd><p>This domain holds struct, union and enum type names.
 </p>
 <a name="index-SYMBOL_005fLABEL_005fDOMAIN"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LABEL_DOMAIN</code>
 <a name="index-gdb_002eSYMBOL_005fLABEL_005fDOMAIN"></a>
 </dt>
 <dd><p>This domain contains names of labels (for gotos).
 </p>
 <a name="index-SYMBOL_005fVARIABLES_005fDOMAIN"></a>
 </dd>
 <dt><code>gdb.SYMBOL_VARIABLES_DOMAIN</code>
 <a name="index-gdb_002eSYMBOL_005fVARIABLES_005fDOMAIN"></a>
 </dt>
 <dd><p>This domain holds a subset of the <code>SYMBOLS_VAR_DOMAIN</code>; it
 contains everything minus functions and types.
 </p>
 <a name="index-SYMBOL_005fFUNCTIONS_005fDOMAIN"></a>
 </dd>
 <dt><code>gdb.SYMBOL_FUNCTION_DOMAIN</code>
 <a name="index-gdb_002eSYMBOL_005fFUNCTION_005fDOMAIN"></a>
 </dt>
 <dd><p>This domain contains all functions.
 </p>
 <a name="index-SYMBOL_005fTYPES_005fDOMAIN"></a>
 </dd>
 <dt><code>gdb.SYMBOL_TYPES_DOMAIN</code>
 <a name="index-gdb_002eSYMBOL_005fTYPES_005fDOMAIN"></a>
 </dt>
 <dd><p>This domain contains all types.
 </p></dd>
 </dl>

 <p>The available address class categories in <code>gdb.Symbol</code> are represented
 as constants in the <code>gdb</code> module:
 </p>
 <dl compact="compact">
 <dd><a name="index-SYMBOL_005fLOC_005fUNDEF"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_UNDEF</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fUNDEF"></a>
 </dt>
 <dd><p>If this is returned by address class, it indicates an error either in
 the symbol information or in <small>GDB</small>&rsquo;s handling of symbols.
 </p>
 <a name="index-SYMBOL_005fLOC_005fCONST"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_CONST</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fCONST"></a>
 </dt>
 <dd><p>Value is constant int.
 </p>
 <a name="index-SYMBOL_005fLOC_005fSTATIC"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_STATIC</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fSTATIC"></a>
 </dt>
 <dd><p>Value is at a fixed address.
 </p>
 <a name="index-SYMBOL_005fLOC_005fREGISTER"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_REGISTER</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fREGISTER"></a>
 </dt>
 <dd><p>Value is in a register.
 </p>
 <a name="index-SYMBOL_005fLOC_005fARG"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_ARG</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fARG"></a>
 </dt>
 <dd><p>Value is an argument.  This value is at the offset stored within the
 symbol inside the frame&rsquo;s argument list.
 </p>
 <a name="index-SYMBOL_005fLOC_005fREF_005fARG"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_REF_ARG</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fREF_005fARG"></a>
 </dt>
 <dd><p>Value address is stored in the frame&rsquo;s argument list.  Just like
 <code>LOC_ARG</code> except that the value&rsquo;s address is stored at the
 offset, not the value itself.
 </p>
 <a name="index-SYMBOL_005fLOC_005fREGPARM_005fADDR"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_REGPARM_ADDR</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fREGPARM_005fADDR"></a>
 </dt>
 <dd><p>Value is a specified register.  Just like <code>LOC_REGISTER</code> except
 the register holds the address of the argument instead of the argument
 itself.
 </p>
 <a name="index-SYMBOL_005fLOC_005fLOCAL"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_LOCAL</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fLOCAL"></a>
 </dt>
 <dd><p>Value is a local variable.
 </p>
 <a name="index-SYMBOL_005fLOC_005fTYPEDEF"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_TYPEDEF</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fTYPEDEF"></a>
 </dt>
 <dd><p>Value not used.  Symbols in the domain <code>SYMBOL_STRUCT_DOMAIN</code> all
 have this class.
 </p>
 <a name="index-SYMBOL_005fLOC_005fBLOCK"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_BLOCK</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fBLOCK"></a>
 </dt>
 <dd><p>Value is a block.
 </p>
 <a name="index-SYMBOL_005fLOC_005fCONST_005fBYTES"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_CONST_BYTES</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fCONST_005fBYTES"></a>
 </dt>
 <dd><p>Value is a byte-sequence.
 </p>
 <a name="index-SYMBOL_005fLOC_005fUNRESOLVED"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_UNRESOLVED</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fUNRESOLVED"></a>
 </dt>
 <dd><p>Value is at a fixed address, but the address of the variable has to be
 determined from the minimal symbol table whenever the variable is
 referenced.
 </p>
 <a name="index-SYMBOL_005fLOC_005fOPTIMIZED_005fOUT"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_OPTIMIZED_OUT</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fOPTIMIZED_005fOUT"></a>
 </dt>
 <dd><p>The value does not actually exist in the program.
 </p>
 <a name="index-SYMBOL_005fLOC_005fCOMPUTED"></a>
 </dd>
 <dt><code>gdb.SYMBOL_LOC_COMPUTED</code>
 <a name="index-gdb_002eSYMBOL_005fLOC_005fCOMPUTED"></a>
 </dt>
 <dd><p>The value&rsquo;s address is a computed location.
 </p></dd>
 </dl>

 <hr>
 <div class="header">
 <p>
 Next: <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python" accesskey="n" rel="next">Symbol Tables In Python</a>, Previous: <a href="Blocks-In-Python.html#Blocks-In-Python" accesskey="p" rel="prev">Blocks In Python</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> &nbsp; [<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>
	<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
	<html>
	<!-- Copyright (C) 1988-2015 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 5.2, http://www.gnu.org/software/texinfo/ -->
	<head>
	<title>Debugging with GDB: Symbols In Python</title>

	<meta name="description" content="Debugging with GDB: Symbols In Python">
	<meta name="keywords" content="Debugging with GDB: Symbols 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="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python" rel="next" title="Symbol Tables In Python">
	<link href="Blocks-In-Python.html#Blocks-In-Python" rel="prev" title="Blocks 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="Symbols-In-Python"></a>
	<div class="header">
	<p>
	Next: <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python" accesskey="n" rel="next">Symbol Tables In Python</a>, Previous: <a href="Blocks-In-Python.html#Blocks-In-Python" accesskey="p" rel="prev">Blocks 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="Python-representation-of-Symbols_002e"></a>
	<h4 class="subsubsection">23.2.2.26 Python representation of Symbols.</h4>

	<a name="index-symbols-in-python"></a>
	<a name="index-gdb_002eSymbol"></a>

	<p><small>GDB</small> represents every variable, function and type as an
	entry in a symbol table. See <a href="Symbols.html#Symbols">Examining the Symbol Table</a>.
	Similarly, Python represents these symbols in <small>GDB</small> with the
	<code>gdb.Symbol</code> object.
	</p>
	<p>The following symbol-related functions are available in the <code>gdb</code>
	module:
	</p>
	<a name="index-gdb_002elookup_005fsymbol"></a>
	<dl>
	<dt><a name="index-gdb_002elookup_005fsymbol-1"></a>Function: <strong>gdb.lookup_symbol</strong> <em>(name <span class="roman">[</span>, block <span class="roman">[</span>, domain<span class="roman">]]</span>)</em></dt>
	<dd><p>This function searches for a symbol by name. The search scope can be
	restricted to the parameters defined in the optional domain and block
	arguments.
	</p>
	<p><var>name</var> is the name of the symbol. It must be a string. The
	optional <var>block</var> argument restricts the search to symbols visible
	in that <var>block</var>. The <var>block</var> argument must be a
	<code>gdb.Block</code> object. If omitted, the block for the current frame
	is used. The optional <var>domain</var> argument restricts
	the search to the domain type. The <var>domain</var> argument must be a
	domain constant defined in the <code>gdb</code> module and described later
	in this chapter.
	</p>
	<p>The result is a tuple of two elements.
	The first element is a <code>gdb.Symbol</code> object or <code>None</code> if the symbol
	is not found.
	If the symbol is found, the second element is <code>True</code> if the symbol
	is a field of a method’s object (e.g., <code>this</code> in C<tt>++</tt>),
	otherwise it is <code>False</code>.
	If the symbol is not found, the second element is <code>False</code>.
	</p></dd></dl>

	<a name="index-gdb_002elookup_005fglobal_005fsymbol"></a>
	<dl>
	<dt><a name="index-gdb_002elookup_005fglobal_005fsymbol-1"></a>Function: <strong>gdb.lookup_global_symbol</strong> <em>(name <span class="roman">[</span>, domain<span class="roman">]</span>)</em></dt>
	<dd><p>This function searches for a global symbol by name.
	The search scope can be restricted to by the domain argument.
	</p>
	<p><var>name</var> is the name of the symbol. It must be a string.
	The optional <var>domain</var> argument restricts the search to the domain type.
	The <var>domain</var> argument must be a domain constant defined in the <code>gdb</code>
	module and described later in this chapter.
	</p>
	<p>The result is a <code>gdb.Symbol</code> object or <code>None</code> if the symbol
	is not found.
	</p></dd></dl>

	<p>A <code>gdb.Symbol</code> object has the following attributes:
	</p>
	<dl>
	<dt><a name="index-Symbol_002etype"></a>Variable: <strong>Symbol.type</strong></dt>
	<dd><p>The type of the symbol or <code>None</code> if no type is recorded.
	This attribute is represented as a <code>gdb.Type</code> object.
	See <a href="Types-In-Python.html#Types-In-Python">Types In Python</a>. This attribute is not writable.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002esymtab"></a>Variable: <strong>Symbol.symtab</strong></dt>
	<dd><p>The symbol table in which the symbol appears. This attribute is
	represented as a <code>gdb.Symtab</code> object. See <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python">Symbol Tables In Python</a>. This attribute is not writable.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002eline"></a>Variable: <strong>Symbol.line</strong></dt>
	<dd><p>The line number in the source code at which the symbol was defined.
	This is an integer.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002ename"></a>Variable: <strong>Symbol.name</strong></dt>
	<dd><p>The name of the symbol as a string. This attribute is not writable.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002elinkage_005fname"></a>Variable: <strong>Symbol.linkage_name</strong></dt>
	<dd><p>The name of the symbol, as used by the linker (i.e., may be mangled).
	This attribute is not writable.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002eprint_005fname"></a>Variable: <strong>Symbol.print_name</strong></dt>
	<dd><p>The name of the symbol in a form suitable for output. This is either
	<code>name</code> or <code>linkage_name</code>, depending on whether the user
	asked <small>GDB</small> to display demangled or mangled names.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002eaddr_005fclass"></a>Variable: <strong>Symbol.addr_class</strong></dt>
	<dd><p>The address class of the symbol. This classifies how to find the value
	of a symbol. Each address class is a constant defined in the
	<code>gdb</code> module and described later in this chapter.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002eneeds_005fframe"></a>Variable: <strong>Symbol.needs_frame</strong></dt>
	<dd><p>This is <code>True</code> if evaluating this symbol’s value requires a frame
	(see <a href="Frames-In-Python.html#Frames-In-Python">Frames In Python</a>) and <code>False</code> otherwise. Typically,
	local variables will require a frame, but other symbols will not.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002eis_005fargument"></a>Variable: <strong>Symbol.is_argument</strong></dt>
	<dd><p><code>True</code> if the symbol is an argument of a function.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002eis_005fconstant"></a>Variable: <strong>Symbol.is_constant</strong></dt>
	<dd><p><code>True</code> if the symbol is a constant.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002eis_005ffunction"></a>Variable: <strong>Symbol.is_function</strong></dt>
	<dd><p><code>True</code> if the symbol is a function or a method.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002eis_005fvariable"></a>Variable: <strong>Symbol.is_variable</strong></dt>
	<dd><p><code>True</code> if the symbol is a variable.
	</p></dd></dl>

	<p>A <code>gdb.Symbol</code> object has the following methods:
	</p>
	<dl>
	<dt><a name="index-Symbol_002eis_005fvalid"></a>Function: <strong>Symbol.is_valid</strong> <em>()</em></dt>
	<dd><p>Returns <code>True</code> if the <code>gdb.Symbol</code> object is valid,
	<code>False</code> if not. A <code>gdb.Symbol</code> object can become invalid if
	the symbol it refers to does not exist in <small>GDB</small> any longer.
	All other <code>gdb.Symbol</code> methods will throw an exception if it is
	invalid at the time the method is called.
	</p></dd></dl>

	<dl>
	<dt><a name="index-Symbol_002evalue"></a>Function: <strong>Symbol.value</strong> <em>(<span class="roman">[</span>frame<span class="roman">]</span>)</em></dt>
	<dd><p>Compute the value of the symbol, as a <code>gdb.Value</code>. For
	functions, this computes the address of the function, cast to the
	appropriate type. If the symbol requires a frame in order to compute
	its value, then <var>frame</var> must be given. If <var>frame</var> is not
	given, or if <var>frame</var> is invalid, then this method will throw an
	exception.
	</p></dd></dl>

	<p>The available domain categories in <code>gdb.Symbol</code> are represented
	as constants in the <code>gdb</code> module:
	</p>
	<dl compact="compact">
	<dd><a name="index-SYMBOL_005fUNDEF_005fDOMAIN"></a>
	</dd>
	<dt><code>gdb.SYMBOL_UNDEF_DOMAIN</code>
	<a name="index-gdb_002eSYMBOL_005fUNDEF_005fDOMAIN"></a>
	</dt>
	<dd><p>This is used when a domain has not been discovered or none of the
	following domains apply. This usually indicates an error either
	in the symbol information or in <small>GDB</small>’s handling of symbols.
	</p>
	<a name="index-SYMBOL_005fVAR_005fDOMAIN"></a>
	</dd>
	<dt><code>gdb.SYMBOL_VAR_DOMAIN</code>
	<a name="index-gdb_002eSYMBOL_005fVAR_005fDOMAIN"></a>
	</dt>
	<dd><p>This domain contains variables, function names, typedef names and enum
	type values.
	</p>
	<a name="index-SYMBOL_005fSTRUCT_005fDOMAIN"></a>
	</dd>
	<dt><code>gdb.SYMBOL_STRUCT_DOMAIN</code>
	<a name="index-gdb_002eSYMBOL_005fSTRUCT_005fDOMAIN"></a>
	</dt>
	<dd><p>This domain holds struct, union and enum type names.
	</p>
	<a name="index-SYMBOL_005fLABEL_005fDOMAIN"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LABEL_DOMAIN</code>
	<a name="index-gdb_002eSYMBOL_005fLABEL_005fDOMAIN"></a>
	</dt>
	<dd><p>This domain contains names of labels (for gotos).
	</p>
	<a name="index-SYMBOL_005fVARIABLES_005fDOMAIN"></a>
	</dd>
	<dt><code>gdb.SYMBOL_VARIABLES_DOMAIN</code>
	<a name="index-gdb_002eSYMBOL_005fVARIABLES_005fDOMAIN"></a>
	</dt>
	<dd><p>This domain holds a subset of the <code>SYMBOLS_VAR_DOMAIN</code>; it
	contains everything minus functions and types.
	</p>
	<a name="index-SYMBOL_005fFUNCTIONS_005fDOMAIN"></a>
	</dd>
	<dt><code>gdb.SYMBOL_FUNCTION_DOMAIN</code>
	<a name="index-gdb_002eSYMBOL_005fFUNCTION_005fDOMAIN"></a>
	</dt>
	<dd><p>This domain contains all functions.
	</p>
	<a name="index-SYMBOL_005fTYPES_005fDOMAIN"></a>
	</dd>
	<dt><code>gdb.SYMBOL_TYPES_DOMAIN</code>
	<a name="index-gdb_002eSYMBOL_005fTYPES_005fDOMAIN"></a>
	</dt>
	<dd><p>This domain contains all types.
	</p></dd>
	</dl>

	<p>The available address class categories in <code>gdb.Symbol</code> are represented
	as constants in the <code>gdb</code> module:
	</p>
	<dl compact="compact">
	<dd><a name="index-SYMBOL_005fLOC_005fUNDEF"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_UNDEF</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fUNDEF"></a>
	</dt>
	<dd><p>If this is returned by address class, it indicates an error either in
	the symbol information or in <small>GDB</small>’s handling of symbols.
	</p>
	<a name="index-SYMBOL_005fLOC_005fCONST"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_CONST</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fCONST"></a>
	</dt>
	<dd><p>Value is constant int.
	</p>
	<a name="index-SYMBOL_005fLOC_005fSTATIC"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_STATIC</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fSTATIC"></a>
	</dt>
	<dd><p>Value is at a fixed address.
	</p>
	<a name="index-SYMBOL_005fLOC_005fREGISTER"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_REGISTER</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fREGISTER"></a>
	</dt>
	<dd><p>Value is in a register.
	</p>
	<a name="index-SYMBOL_005fLOC_005fARG"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_ARG</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fARG"></a>
	</dt>
	<dd><p>Value is an argument. This value is at the offset stored within the
	symbol inside the frame’s argument list.
	</p>
	<a name="index-SYMBOL_005fLOC_005fREF_005fARG"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_REF_ARG</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fREF_005fARG"></a>
	</dt>
	<dd><p>Value address is stored in the frame’s argument list. Just like
	<code>LOC_ARG</code> except that the value’s address is stored at the
	offset, not the value itself.
	</p>
	<a name="index-SYMBOL_005fLOC_005fREGPARM_005fADDR"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_REGPARM_ADDR</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fREGPARM_005fADDR"></a>
	</dt>
	<dd><p>Value is a specified register. Just like <code>LOC_REGISTER</code> except
	the register holds the address of the argument instead of the argument
	itself.
	</p>
	<a name="index-SYMBOL_005fLOC_005fLOCAL"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_LOCAL</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fLOCAL"></a>
	</dt>
	<dd><p>Value is a local variable.
	</p>
	<a name="index-SYMBOL_005fLOC_005fTYPEDEF"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_TYPEDEF</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fTYPEDEF"></a>
	</dt>
	<dd><p>Value not used. Symbols in the domain <code>SYMBOL_STRUCT_DOMAIN</code> all
	have this class.
	</p>
	<a name="index-SYMBOL_005fLOC_005fBLOCK"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_BLOCK</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fBLOCK"></a>
	</dt>
	<dd><p>Value is a block.
	</p>
	<a name="index-SYMBOL_005fLOC_005fCONST_005fBYTES"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_CONST_BYTES</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fCONST_005fBYTES"></a>
	</dt>
	<dd><p>Value is a byte-sequence.
	</p>
	<a name="index-SYMBOL_005fLOC_005fUNRESOLVED"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_UNRESOLVED</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fUNRESOLVED"></a>
	</dt>
	<dd><p>Value is at a fixed address, but the address of the variable has to be
	determined from the minimal symbol table whenever the variable is
	referenced.
	</p>
	<a name="index-SYMBOL_005fLOC_005fOPTIMIZED_005fOUT"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_OPTIMIZED_OUT</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fOPTIMIZED_005fOUT"></a>
	</dt>
	<dd><p>The value does not actually exist in the program.
	</p>
	<a name="index-SYMBOL_005fLOC_005fCOMPUTED"></a>
	</dd>
	<dt><code>gdb.SYMBOL_LOC_COMPUTED</code>
	<a name="index-gdb_002eSYMBOL_005fLOC_005fCOMPUTED"></a>
	</dt>
	<dd><p>The value’s address is a computed location.
	</p></dd>
	</dl>

	<hr>
	<div class="header">
	<p>
	Next: <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python" accesskey="n" rel="next">Symbol Tables In Python</a>, Previous: <a href="Blocks-In-Python.html#Blocks-In-Python" accesskey="p" rel="prev">Blocks 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>