1<html lang="en"> 2<head> 3<title>Types In Python - Debugging with GDB</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Debugging with GDB"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="Python-API.html#Python-API" title="Python API"> 9<link rel="prev" href="Values-From-Inferior.html#Values-From-Inferior" title="Values From Inferior"> 10<link rel="next" href="Pretty-Printing-API.html#Pretty-Printing-API" title="Pretty Printing API"> 11<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 12<!-- 13Copyright (C) 1988-2013 Free Software Foundation, Inc. 14 15Permission is granted to copy, distribute and/or modify this document 16under the terms of the GNU Free Documentation License, Version 1.3 or 17any later version published by the Free Software Foundation; with the 18Invariant Sections being ``Free Software'' and ``Free Software Needs 19Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,'' 20and with the Back-Cover Texts as in (a) below. 21 22(a) The FSF's Back-Cover Text is: ``You are free to copy and modify 23this GNU Manual. 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It must be a string. 65 66 <p>If <var>block</var> is given, then <var>name</var> is looked up in that scope. 67Otherwise, it is searched for globally. 68 69 <p>Ordinarily, this function will return an instance of <code>gdb.Type</code>. 70If the named type cannot be found, it will throw an exception. 71</p></blockquote></div> 72 73 <p>If the type is a structure or class type, or an enum type, the fields 74of that type can be accessed using the Python <dfn>dictionary syntax</dfn>. 75For example, if <code>some_type</code> is a <code>gdb.Type</code> instance holding 76a structure type, you can access its <code>foo</code> field with: 77 78<pre class="smallexample"> bar = some_type['foo'] 79</pre> 80 <p><code>bar</code> will be a <code>gdb.Field</code> object; see below under the 81description of the <code>Type.fields</code> method for a description of the 82<code>gdb.Field</code> class. 83 84 <p>An instance of <code>Type</code> has the following attributes: 85 86<div class="defun"> 87— Variable: <b>Type.code</b><var><a name="index-Type_002ecode-1804"></a></var><br> 88<blockquote><p>The type code for this type. The type code will be one of the 89<code>TYPE_CODE_</code> constants defined below. 90</p></blockquote></div> 91 92<div class="defun"> 93— Variable: <b>Type.sizeof</b><var><a name="index-Type_002esizeof-1805"></a></var><br> 94<blockquote><p>The size of this type, in target <code>char</code> units. Usually, a 95target's <code>char</code> type will be an 8-bit byte. However, on some 96unusual platforms, this type may have a different size. 97</p></blockquote></div> 98 99<div class="defun"> 100— Variable: <b>Type.tag</b><var><a name="index-Type_002etag-1806"></a></var><br> 101<blockquote><p>The tag name for this type. The tag name is the name after 102<code>struct</code>, <code>union</code>, or <code>enum</code> in C and C<tt>++</tt>; not all 103languages have this concept. If this type has no tag name, then 104<code>None</code> is returned. 105</p></blockquote></div> 106 107 <p>The following methods are provided: 108 109<div class="defun"> 110— Function: <b>Type.fields</b> ()<var><a name="index-Type_002efields-1807"></a></var><br> 111<blockquote><p>For structure and union types, this method returns the fields. Range 112types have two fields, the minimum and maximum values. Enum types 113have one field per enum constant. Function and method types have one 114field per parameter. The base types of C<tt>++</tt> classes are also 115represented as fields. If the type has no fields, or does not fit 116into one of these categories, an empty sequence will be returned. 117 118 <p>Each field is a <code>gdb.Field</code> object, with some pre-defined attributes: 119 <dl> 120<dt><code>bitpos</code><dd>This attribute is not available for <code>static</code> fields (as in 121C<tt>++</tt> or Java). For non-<code>static</code> fields, the value is the bit 122position of the field. For <code>enum</code> fields, the value is the 123enumeration member's integer representation. 124 125 <br><dt><code>name</code><dd>The name of the field, or <code>None</code> for anonymous fields. 126 127 <br><dt><code>artificial</code><dd>This is <code>True</code> if the field is artificial, usually meaning that 128it was provided by the compiler and not the user. This attribute is 129always provided, and is <code>False</code> if the field is not artificial. 130 131 <br><dt><code>is_base_class</code><dd>This is <code>True</code> if the field represents a base class of a C<tt>++</tt> 132structure. This attribute is always provided, and is <code>False</code> 133if the field is not a base class of the type that is the argument of 134<code>fields</code>, or if that type was not a C<tt>++</tt> class. 135 136 <br><dt><code>bitsize</code><dd>If the field is packed, or is a bitfield, then this will have a 137non-zero value, which is the size of the field in bits. Otherwise, 138this will be zero; in this case the field's size is given by its type. 139 140 <br><dt><code>type</code><dd>The type of the field. This is usually an instance of <code>Type</code>, 141but it can be <code>None</code> in some situations. 142</dl> 143 </p></blockquote></div> 144 145<div class="defun"> 146— Function: <b>Type.array</b> (<var>n1 </var><span class="roman">[</span><var>, n2</var><span class="roman">]</span>)<var><a name="index-Type_002earray-1808"></a></var><br> 147<blockquote><p>Return a new <code>gdb.Type</code> object which represents an array of this 148type. If one argument is given, it is the inclusive upper bound of 149the array; in this case the lower bound is zero. If two arguments are 150given, the first argument is the lower bound of the array, and the 151second argument is the upper bound of the array. An array's length 152must not be negative, but the bounds can be. 153</p></blockquote></div> 154 155<div class="defun"> 156— Function: <b>Type.vector</b> (<var>n1 </var><span class="roman">[</span><var>, n2</var><span class="roman">]</span>)<var><a name="index-Type_002evector-1809"></a></var><br> 157<blockquote><p>Return a new <code>gdb.Type</code> object which represents a vector of this 158type. If one argument is given, it is the inclusive upper bound of 159the vector; in this case the lower bound is zero. If two arguments are 160given, the first argument is the lower bound of the vector, and the 161second argument is the upper bound of the vector. A vector's length 162must not be negative, but the bounds can be. 163 164 <p>The difference between an <code>array</code> and a <code>vector</code> is that 165arrays behave like in C: when used in expressions they decay to a pointer 166to the first element whereas vectors are treated as first class values. 167</p></blockquote></div> 168 169<div class="defun"> 170— Function: <b>Type.const</b> ()<var><a name="index-Type_002econst-1810"></a></var><br> 171<blockquote><p>Return a new <code>gdb.Type</code> object which represents a 172<code>const</code>-qualified variant of this type. 173</p></blockquote></div> 174 175<div class="defun"> 176— Function: <b>Type.volatile</b> ()<var><a name="index-Type_002evolatile-1811"></a></var><br> 177<blockquote><p>Return a new <code>gdb.Type</code> object which represents a 178<code>volatile</code>-qualified variant of this type. 179</p></blockquote></div> 180 181<div class="defun"> 182— Function: <b>Type.unqualified</b> ()<var><a name="index-Type_002eunqualified-1812"></a></var><br> 183<blockquote><p>Return a new <code>gdb.Type</code> object which represents an unqualified 184variant of this type. That is, the result is neither <code>const</code> nor 185<code>volatile</code>. 186</p></blockquote></div> 187 188<div class="defun"> 189— Function: <b>Type.range</b> ()<var><a name="index-Type_002erange-1813"></a></var><br> 190<blockquote><p>Return a Python <code>Tuple</code> object that contains two elements: the 191low bound of the argument type and the high bound of that type. If 192the type does not have a range, <span class="sc">gdb</span> will raise a 193<code>gdb.error</code> exception (see <a href="Exception-Handling.html#Exception-Handling">Exception Handling</a>). 194</p></blockquote></div> 195 196<div class="defun"> 197— Function: <b>Type.reference</b> ()<var><a name="index-Type_002ereference-1814"></a></var><br> 198<blockquote><p>Return a new <code>gdb.Type</code> object which represents a reference to this 199type. 200</p></blockquote></div> 201 202<div class="defun"> 203— Function: <b>Type.pointer</b> ()<var><a name="index-Type_002epointer-1815"></a></var><br> 204<blockquote><p>Return a new <code>gdb.Type</code> object which represents a pointer to this 205type. 206</p></blockquote></div> 207 208<div class="defun"> 209— Function: <b>Type.strip_typedefs</b> ()<var><a name="index-Type_002estrip_005ftypedefs-1816"></a></var><br> 210<blockquote><p>Return a new <code>gdb.Type</code> that represents the real type, 211after removing all layers of typedefs. 212</p></blockquote></div> 213 214<div class="defun"> 215— Function: <b>Type.target</b> ()<var><a name="index-Type_002etarget-1817"></a></var><br> 216<blockquote><p>Return a new <code>gdb.Type</code> object which represents the target type 217of this type. 218 219 <p>For a pointer type, the target type is the type of the pointed-to 220object. For an array type (meaning C-like arrays), the target type is 221the type of the elements of the array. For a function or method type, 222the target type is the type of the return value. For a complex type, 223the target type is the type of the elements. For a typedef, the 224target type is the aliased type. 225 226 <p>If the type does not have a target, this method will throw an 227exception. 228</p></blockquote></div> 229 230<div class="defun"> 231— Function: <b>Type.template_argument</b> (<var>n </var><span class="roman">[</span><var>, block</var><span class="roman">]</span>)<var><a name="index-Type_002etemplate_005fargument-1818"></a></var><br> 232<blockquote><p>If this <code>gdb.Type</code> is an instantiation of a template, this will 233return a new <code>gdb.Type</code> which represents the type of the 234<var>n</var>th template argument. 235 236 <p>If this <code>gdb.Type</code> is not a template type, this will throw an 237exception. Ordinarily, only C<tt>++</tt> code will have template types. 238 239 <p>If <var>block</var> is given, then <var>name</var> is looked up in that scope. 240Otherwise, it is searched for globally. 241</p></blockquote></div> 242 243 <p>Each type has a code, which indicates what category this type falls 244into. The available type categories are represented by constants 245defined in the <code>gdb</code> module: 246 247 248<a name="index-TYPE_005fCODE_005fPTR-1819"></a> 249<a name="index-gdb_002eTYPE_005fCODE_005fPTR-1820"></a> 250<dl><dt><code>gdb.TYPE_CODE_PTR</code><dd>The type is a pointer. 251 252 <p><a name="index-TYPE_005fCODE_005fARRAY-1821"></a><a name="index-gdb_002eTYPE_005fCODE_005fARRAY-1822"></a><br><dt><code>gdb.TYPE_CODE_ARRAY</code><dd>The type is an array. 253 254 <p><a name="index-TYPE_005fCODE_005fSTRUCT-1823"></a><a name="index-gdb_002eTYPE_005fCODE_005fSTRUCT-1824"></a><br><dt><code>gdb.TYPE_CODE_STRUCT</code><dd>The type is a structure. 255 256 <p><a name="index-TYPE_005fCODE_005fUNION-1825"></a><a name="index-gdb_002eTYPE_005fCODE_005fUNION-1826"></a><br><dt><code>gdb.TYPE_CODE_UNION</code><dd>The type is a union. 257 258 <p><a name="index-TYPE_005fCODE_005fENUM-1827"></a><a name="index-gdb_002eTYPE_005fCODE_005fENUM-1828"></a><br><dt><code>gdb.TYPE_CODE_ENUM</code><dd>The type is an enum. 259 260 <p><a name="index-TYPE_005fCODE_005fFLAGS-1829"></a><a name="index-gdb_002eTYPE_005fCODE_005fFLAGS-1830"></a><br><dt><code>gdb.TYPE_CODE_FLAGS</code><dd>A bit flags type, used for things such as status registers. 261 262 <p><a name="index-TYPE_005fCODE_005fFUNC-1831"></a><a name="index-gdb_002eTYPE_005fCODE_005fFUNC-1832"></a><br><dt><code>gdb.TYPE_CODE_FUNC</code><dd>The type is a function. 263 264 <p><a name="index-TYPE_005fCODE_005fINT-1833"></a><a name="index-gdb_002eTYPE_005fCODE_005fINT-1834"></a><br><dt><code>gdb.TYPE_CODE_INT</code><dd>The type is an integer type. 265 266 <p><a name="index-TYPE_005fCODE_005fFLT-1835"></a><a name="index-gdb_002eTYPE_005fCODE_005fFLT-1836"></a><br><dt><code>gdb.TYPE_CODE_FLT</code><dd>A floating point type. 267 268 <p><a name="index-TYPE_005fCODE_005fVOID-1837"></a><a name="index-gdb_002eTYPE_005fCODE_005fVOID-1838"></a><br><dt><code>gdb.TYPE_CODE_VOID</code><dd>The special type <code>void</code>. 269 270 <p><a name="index-TYPE_005fCODE_005fSET-1839"></a><a name="index-gdb_002eTYPE_005fCODE_005fSET-1840"></a><br><dt><code>gdb.TYPE_CODE_SET</code><dd>A Pascal set type. 271 272 <p><a name="index-TYPE_005fCODE_005fRANGE-1841"></a><a name="index-gdb_002eTYPE_005fCODE_005fRANGE-1842"></a><br><dt><code>gdb.TYPE_CODE_RANGE</code><dd>A range type, that is, an integer type with bounds. 273 274 <p><a name="index-TYPE_005fCODE_005fSTRING-1843"></a><a name="index-gdb_002eTYPE_005fCODE_005fSTRING-1844"></a><br><dt><code>gdb.TYPE_CODE_STRING</code><dd>A string type. Note that this is only used for certain languages with 275language-defined string types; C strings are not represented this way. 276 277 <p><a name="index-TYPE_005fCODE_005fBITSTRING-1845"></a><a name="index-gdb_002eTYPE_005fCODE_005fBITSTRING-1846"></a><br><dt><code>gdb.TYPE_CODE_BITSTRING</code><dd>A string of bits. It is deprecated. 278 279 <p><a name="index-TYPE_005fCODE_005fERROR-1847"></a><a name="index-gdb_002eTYPE_005fCODE_005fERROR-1848"></a><br><dt><code>gdb.TYPE_CODE_ERROR</code><dd>An unknown or erroneous type. 280 281 <p><a name="index-TYPE_005fCODE_005fMETHOD-1849"></a><a name="index-gdb_002eTYPE_005fCODE_005fMETHOD-1850"></a><br><dt><code>gdb.TYPE_CODE_METHOD</code><dd>A method type, as found in C<tt>++</tt> or Java. 282 283 <p><a name="index-TYPE_005fCODE_005fMETHODPTR-1851"></a><a name="index-gdb_002eTYPE_005fCODE_005fMETHODPTR-1852"></a><br><dt><code>gdb.TYPE_CODE_METHODPTR</code><dd>A pointer-to-member-function. 284 285 <p><a name="index-TYPE_005fCODE_005fMEMBERPTR-1853"></a><a name="index-gdb_002eTYPE_005fCODE_005fMEMBERPTR-1854"></a><br><dt><code>gdb.TYPE_CODE_MEMBERPTR</code><dd>A pointer-to-member. 286 287 <p><a name="index-TYPE_005fCODE_005fREF-1855"></a><a name="index-gdb_002eTYPE_005fCODE_005fREF-1856"></a><br><dt><code>gdb.TYPE_CODE_REF</code><dd>A reference type. 288 289 <p><a name="index-TYPE_005fCODE_005fCHAR-1857"></a><a name="index-gdb_002eTYPE_005fCODE_005fCHAR-1858"></a><br><dt><code>gdb.TYPE_CODE_CHAR</code><dd>A character type. 290 291 <p><a name="index-TYPE_005fCODE_005fBOOL-1859"></a><a name="index-gdb_002eTYPE_005fCODE_005fBOOL-1860"></a><br><dt><code>gdb.TYPE_CODE_BOOL</code><dd>A boolean type. 292 293 <p><a name="index-TYPE_005fCODE_005fCOMPLEX-1861"></a><a name="index-gdb_002eTYPE_005fCODE_005fCOMPLEX-1862"></a><br><dt><code>gdb.TYPE_CODE_COMPLEX</code><dd>A complex float type. 294 295 <p><a name="index-TYPE_005fCODE_005fTYPEDEF-1863"></a><a name="index-gdb_002eTYPE_005fCODE_005fTYPEDEF-1864"></a><br><dt><code>gdb.TYPE_CODE_TYPEDEF</code><dd>A typedef to some other type. 296 297 <p><a name="index-TYPE_005fCODE_005fNAMESPACE-1865"></a><a name="index-gdb_002eTYPE_005fCODE_005fNAMESPACE-1866"></a><br><dt><code>gdb.TYPE_CODE_NAMESPACE</code><dd>A C<tt>++</tt> namespace. 298 299 <p><a name="index-TYPE_005fCODE_005fDECFLOAT-1867"></a><a name="index-gdb_002eTYPE_005fCODE_005fDECFLOAT-1868"></a><br><dt><code>gdb.TYPE_CODE_DECFLOAT</code><dd>A decimal floating point type. 300 301 <p><a name="index-TYPE_005fCODE_005fINTERNAL_005fFUNCTION-1869"></a><a name="index-gdb_002eTYPE_005fCODE_005fINTERNAL_005fFUNCTION-1870"></a><br><dt><code>gdb.TYPE_CODE_INTERNAL_FUNCTION</code><dd>A function internal to <span class="sc">gdb</span>. This is the type used to represent 302convenience functions. 303</dl> 304 305 <p>Further support for types is provided in the <code>gdb.types</code> 306Python module (see <a href="gdb_002etypes.html#gdb_002etypes">gdb.types</a>). 307 308 </body></html> 309 310