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<h5 class="subsubsection">23.2.2.17 Python representation of Symbols.</h5>
<p><a name="index-symbols-in-python-1841"></a><a name="index-gdb_002eSymbol-1842"></a>
<span class="sc">gdb</span> 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 <span class="sc">gdb</span> with the
<code>gdb.Symbol</code> object.
<p>The following symbol-related functions are available in the <code>gdb</code>
module:
<p><a name="index-gdb_002elookup_005fsymbol-1843"></a>
<div class="defun">
&mdash; Function: <b>lookup_symbol</b><var> name </var>[<var>block</var>] [<var>domain</var>]<var><a name="index-lookup_005fsymbol-1844"></a></var><br>
<blockquote><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><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. 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></blockquote></div>
<p>A <code>gdb.Symbol</code> object has the following attributes:
<dl>
<div class="defun">
&mdash; Instance Variable of Symbol: <b>symtab</b><var><a name="index-symtab-1845"></a></var><br>
<blockquote> <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></blockquote></div>
<div class="defun">
&mdash; Instance Variable of Symbol: <b>name</b><var><a name="index-name-1846"></a></var><br>
<blockquote> <p>The name of the symbol as a string. This attribute is not writable.
</p></blockquote></div>
<div class="defun">
&mdash; Instance Variable of Symbol: <b>linkage_name</b><var><a name="index-linkage_005fname-1847"></a></var><br>
<blockquote> <p>The name of the symbol, as used by the linker (i.e., may be mangled).
This attribute is not writable.
</p></blockquote></div>
<div class="defun">
&mdash; Instance Variable of Symbol: <b>print_name</b><var><a name="index-print_005fname-1848"></a></var><br>
<blockquote> <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 <span class="sc">gdb</span> to display demangled or mangled names.
</p></blockquote></div>
<div class="defun">
&mdash; Instance Variable of Symbol: <b>addr_class</b><var><a name="index-addr_005fclass-1849"></a></var><br>
<blockquote> <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></blockquote></div>
<div class="defun">
&mdash; Instance Variable of Symbol: <b>is_argument</b><var><a name="index-is_005fargument-1850"></a></var><br>
<blockquote> <p><code>True</code> if the symbol is an argument of a function.
</p></blockquote></div>
<div class="defun">
&mdash; Instance Variable of Symbol: <b>is_constant</b><var><a name="index-is_005fconstant-1851"></a></var><br>
<blockquote> <p><code>True</code> if the symbol is a constant.
</p></blockquote></div>
<div class="defun">
&mdash; Instance Variable of Symbol: <b>is_function</b><var><a name="index-is_005ffunction-1852"></a></var><br>
<blockquote> <p><code>True</code> if the symbol is a function or a method.
</p></blockquote></div>
<div class="defun">
&mdash; Instance Variable of Symbol: <b>is_variable</b><var><a name="index-is_005fvariable-1853"></a></var><br>
<blockquote> <p><code>True</code> if the symbol is a variable.
</p></blockquote></div>
</dl>
<p>The available domain categories in <code>gdb.Symbol</code> are represented
as constants in the <code>gdb</code> module:
<a name="index-SYMBOL_005fUNDEF_005fDOMAIN-1854"></a>
<a name="index-gdb_002eSYMBOL_005fUNDEF_005fDOMAIN-1855"></a>
<dl><dt><code>SYMBOL_UNDEF_DOMAIN</code><dd>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 <span class="sc">gdb</span>'s handling of symbols.
<a name="index-SYMBOL_005fVAR_005fDOMAIN-1856"></a><a name="index-gdb_002eSYMBOL_005fVAR_005fDOMAIN-1857"></a><br><dt><code>SYMBOL_VAR_DOMAIN</code><dd>This domain contains variables, function names, typedef names and enum
type values.
<a name="index-SYMBOL_005fSTRUCT_005fDOMAIN-1858"></a><a name="index-gdb_002eSYMBOL_005fSTRUCT_005fDOMAIN-1859"></a><br><dt><code>SYMBOL_STRUCT_DOMAIN</code><dd>This domain holds struct, union and enum type names.
<a name="index-SYMBOL_005fLABEL_005fDOMAIN-1860"></a><a name="index-gdb_002eSYMBOL_005fLABEL_005fDOMAIN-1861"></a><br><dt><code>SYMBOL_LABEL_DOMAIN</code><dd>This domain contains names of labels (for gotos).
<a name="index-SYMBOL_005fVARIABLES_005fDOMAIN-1862"></a><a name="index-gdb_002eSYMBOL_005fVARIABLES_005fDOMAIN-1863"></a><br><dt><code>SYMBOL_VARIABLES_DOMAIN</code><dd>This domain holds a subset of the <code>SYMBOLS_VAR_DOMAIN</code>; it
contains everything minus functions and types.
<a name="index-SYMBOL_005fFUNCTIONS_005fDOMAIN-1864"></a><a name="index-gdb_002eSYMBOL_005fFUNCTIONS_005fDOMAIN-1865"></a><br><dt><code>SYMBOL_FUNCTION_DOMAIN</code><dd>This domain contains all functions.
<a name="index-SYMBOL_005fTYPES_005fDOMAIN-1866"></a><a name="index-gdb_002eSYMBOL_005fTYPES_005fDOMAIN-1867"></a><br><dt><code>SYMBOL_TYPES_DOMAIN</code><dd>This domain contains all types.
</dl>
<p>The available address class categories in <code>gdb.Symbol</code> are represented
as constants in the <code>gdb</code> module:
<a name="index-SYMBOL_005fLOC_005fUNDEF-1868"></a>
<a name="index-gdb_002eSYMBOL_005fLOC_005fUNDEF-1869"></a>
<dl><dt><code>SYMBOL_LOC_UNDEF</code><dd>If this is returned by address class, it indicates an error either in
the symbol information or in <span class="sc">gdb</span>'s handling of symbols.
<a name="index-SYMBOL_005fLOC_005fCONST-1870"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fCONST-1871"></a><br><dt><code>SYMBOL_LOC_CONST</code><dd>Value is constant int.
<a name="index-SYMBOL_005fLOC_005fSTATIC-1872"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fSTATIC-1873"></a><br><dt><code>SYMBOL_LOC_STATIC</code><dd>Value is at a fixed address.
<a name="index-SYMBOL_005fLOC_005fREGISTER-1874"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fREGISTER-1875"></a><br><dt><code>SYMBOL_LOC_REGISTER</code><dd>Value is in a register.
<a name="index-SYMBOL_005fLOC_005fARG-1876"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fARG-1877"></a><br><dt><code>SYMBOL_LOC_ARG</code><dd>Value is an argument. This value is at the offset stored within the
symbol inside the frame's argument list.
<a name="index-SYMBOL_005fLOC_005fREF_005fARG-1878"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fREF_005fARG-1879"></a><br><dt><code>SYMBOL_LOC_REF_ARG</code><dd>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.
<a name="index-SYMBOL_005fLOC_005fREGPARM_005fADDR-1880"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fREGPARM_005fADDR-1881"></a><br><dt><code>SYMBOL_LOC_REGPARM_ADDR</code><dd>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.
<a name="index-SYMBOL_005fLOC_005fLOCAL-1882"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fLOCAL-1883"></a><br><dt><code>SYMBOL_LOC_LOCAL</code><dd>Value is a local variable.
<a name="index-SYMBOL_005fLOC_005fTYPEDEF-1884"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fTYPEDEF-1885"></a><br><dt><code>SYMBOL_LOC_TYPEDEF</code><dd>Value not used. Symbols in the domain <code>SYMBOL_STRUCT_DOMAIN</code> all
have this class.
<a name="index-SYMBOL_005fLOC_005fBLOCK-1886"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fBLOCK-1887"></a><br><dt><code>SYMBOL_LOC_BLOCK</code><dd>Value is a block.
<a name="index-SYMBOL_005fLOC_005fCONST_005fBYTES-1888"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fCONST_005fBYTES-1889"></a><br><dt><code>SYMBOL_LOC_CONST_BYTES</code><dd>Value is a byte-sequence.
<a name="index-SYMBOL_005fLOC_005fUNRESOLVED-1890"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fUNRESOLVED-1891"></a><br><dt><code>SYMBOL_LOC_UNRESOLVED</code><dd>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.
<a name="index-SYMBOL_005fLOC_005fOPTIMIZED_005fOUT-1892"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fOPTIMIZED_005fOUT-1893"></a><br><dt><code>SYMBOL_LOC_OPTIMIZED_OUT</code><dd>The value does not actually exist in the program.
<a name="index-SYMBOL_005fLOC_005fCOMPUTED-1894"></a><a name="index-gdb_002eSYMBOL_005fLOC_005fCOMPUTED-1895"></a><br><dt><code>SYMBOL_LOC_COMPUTED</code><dd>The value's address is a computed location.
</dl>
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