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<title>Debugging with GDB: Types In Guile</title>
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<a name="Types-In-Guile"></a>
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<div class="header">
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<p>
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Next: <a href="Guile-Pretty-Printing-API.html#Guile-Pretty-Printing-API" accesskey="n" rel="next">Guile Pretty Printing API</a>, Previous: <a href="Arithmetic-In-Guile.html#Arithmetic-In-Guile" accesskey="p" rel="previous">Arithmetic In Guile</a>, Up: <a href="Guile-API.html#Guile-API" accesskey="u" rel="up">Guile 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>
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</div>
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<hr>
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<a name="Types-In-Guile-1"></a>
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<h4 class="subsubsection">23.3.3.7 Types In Guile</h4>
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<a name="index-types-in-guile"></a>
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<a name="index-guile_002c-working-with-types"></a>
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<a name="index-_003cgdb_003atype_003e"></a>
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<p><small>GDB</small> represents types from the inferior in objects of type
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<code><gdb:type></code>.
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</p>
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<p>The following type-related procedures are provided by the
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<code>(gdb)</code> module.
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</p>
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<dl>
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<dt><a name="index-type_003f"></a>Scheme Procedure: <strong>type?</strong> <em>object</em></dt>
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<dd><p>Return <code>#t</code> if <var>object</var> is an object of type <code><gdb:type></code>.
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Otherwise return <code>#f</code>.
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</p></dd></dl>
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<dl>
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<dt><a name="index-lookup_002dtype"></a>Scheme Procedure: <strong>lookup-type</strong> <em>name <span class="roman">[</span>#:block block<span class="roman">]</span></em></dt>
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<dd><p>This function looks up a type by its <var>name</var>, which must be a string.
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</p>
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<p>If <var>block</var> is given, it is an object of type <code><gdb:block></code>,
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and <var>name</var> is looked up in that scope.
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Otherwise, it is searched for globally.
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</p>
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<p>Ordinarily, this function will return an instance of <code><gdb:type></code>.
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If the named type cannot be found, it will throw an exception.
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</p></dd></dl>
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<dl>
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<dt><a name="index-type_002dcode"></a>Scheme Procedure: <strong>type-code</strong> <em>type</em></dt>
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<dd><p>Return the type code of <var>type</var>. The type code will be one of the
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<code>TYPE_CODE_</code> constants defined below.
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</p></dd></dl>
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<dl>
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<dt><a name="index-type_002dtag"></a>Scheme Procedure: <strong>type-tag</strong> <em>type</em></dt>
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<dd><p>Return the tag name of <var>type</var>. The tag name is the name after
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<code>struct</code>, <code>union</code>, or <code>enum</code> in C and C<tt>++</tt>; not all
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languages have this concept. If this type has no tag name, then
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<code>#f</code> is returned.
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</p></dd></dl>
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<dl>
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<dt><a name="index-type_002dname"></a>Scheme Procedure: <strong>type-name</strong> <em>type</em></dt>
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<dd><p>Return the name of <var>type</var>.
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If this type has no name, then <code>#f</code> is returned.
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</p></dd></dl>
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<dl>
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<dt><a name="index-type_002dprint_002dname"></a>Scheme Procedure: <strong>type-print-name</strong> <em>type</em></dt>
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<dd><p>Return the print name of <var>type</var>.
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This returns something even for anonymous types.
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For example, for an anonymous C struct <code>"struct {...}"</code> is returned.
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</p></dd></dl>
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<dl>
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<dt><a name="index-type_002dsizeof"></a>Scheme Procedure: <strong>type-sizeof</strong> <em>type</em></dt>
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<dd><p>Return the size of this type, in target <code>char</code> units. Usually, a
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target’s <code>char</code> type will be an 8-bit byte. However, on some
|
unusual platforms, this type may have a different size.
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</p></dd></dl>
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<dl>
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<dt><a name="index-type_002dstrip_002dtypedefs"></a>Scheme Procedure: <strong>type-strip-typedefs</strong> <em>type</em></dt>
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<dd><p>Return a new <code><gdb:type></code> that represents the real type of <var>type</var>,
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after removing all layers of typedefs.
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</p></dd></dl>
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<dl>
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<dt><a name="index-type_002darray"></a>Scheme Procedure: <strong>type-array</strong> <em>type n1 <span class="roman">[</span>n2<span class="roman">]</span></em></dt>
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<dd><p>Return a new <code><gdb:type></code> object which represents an array of this
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type. If one argument is given, it is the inclusive upper bound of
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the array; in this case the lower bound is zero. If two arguments are
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given, the first argument is the lower bound of the array, and the
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second argument is the upper bound of the array. An array’s length
|
must not be negative, but the bounds can be.
|
</p></dd></dl>
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|
<dl>
|
<dt><a name="index-type_002dvector"></a>Scheme Procedure: <strong>type-vector</strong> <em>type n1 <span class="roman">[</span>n2<span class="roman">]</span></em></dt>
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<dd><p>Return a new <code><gdb:type></code> object which represents a vector of this
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type. If one argument is given, it is the inclusive upper bound of
|
the vector; in this case the lower bound is zero. If two arguments are
|
given, the first argument is the lower bound of the vector, and the
|
second argument is the upper bound of the vector. A vector’s length
|
must not be negative, but the bounds can be.
|
</p>
|
<p>The difference between an <code>array</code> and a <code>vector</code> is that
|
arrays behave like in C: when used in expressions they decay to a pointer
|
to the first element whereas vectors are treated as first class values.
|
</p></dd></dl>
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|
<dl>
|
<dt><a name="index-type_002dpointer"></a>Scheme Procedure: <strong>type-pointer</strong> <em>type</em></dt>
|
<dd><p>Return a new <code><gdb:type></code> object which represents a pointer to
|
<var>type</var>.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-type_002drange"></a>Scheme Procedure: <strong>type-range</strong> <em>type</em></dt>
|
<dd><p>Return a list of two elements: the low bound and high bound of <var>type</var>.
|
If <var>type</var> does not have a range, an exception is thrown.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-type_002dreference"></a>Scheme Procedure: <strong>type-reference</strong> <em>type</em></dt>
|
<dd><p>Return a new <code><gdb:type></code> object which represents a reference to
|
<var>type</var>.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-type_002dtarget"></a>Scheme Procedure: <strong>type-target</strong> <em>type</em></dt>
|
<dd><p>Return a new <code><gdb:type></code> object which represents the target type
|
of <var>type</var>.
|
</p>
|
<p>For a pointer type, the target type is the type of the pointed-to
|
object. For an array type (meaning C-like arrays), the target type is
|
the type of the elements of the array. For a function or method type,
|
the target type is the type of the return value. For a complex type,
|
the target type is the type of the elements. For a typedef, the
|
target type is the aliased type.
|
</p>
|
<p>If the type does not have a target, this method will throw an
|
exception.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-type_002dconst"></a>Scheme Procedure: <strong>type-const</strong> <em>type</em></dt>
|
<dd><p>Return a new <code><gdb:type></code> object which represents a
|
<code>const</code>-qualified variant of <var>type</var>.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-type_002dvolatile"></a>Scheme Procedure: <strong>type-volatile</strong> <em>type</em></dt>
|
<dd><p>Return a new <code><gdb:type></code> object which represents a
|
<code>volatile</code>-qualified variant of <var>type</var>.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-type_002dunqualified"></a>Scheme Procedure: <strong>type-unqualified</strong> <em>type</em></dt>
|
<dd><p>Return a new <code><gdb:type></code> object which represents an unqualified
|
variant of <var>type</var>. That is, the result is neither <code>const</code> nor
|
<code>volatile</code>.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-type_002dnum_002dfields"></a>Scheme Procedure: <strong>type-num-fields</strong></dt>
|
<dd><p>Return the number of fields of <code><gdb:type></code> <var>type</var>.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-type_002dfields"></a>Scheme Procedure: <strong>type-fields</strong> <em>type</em></dt>
|
<dd><p>Return the fields of <var>type</var> as a list.
|
For structure and union types, <code>fields</code> has the usual meaning.
|
Range types have two fields, the minimum and maximum values. Enum types
|
have one field per enum constant. Function and method types have one
|
field per parameter. The base types of C<tt>++</tt> classes are also
|
represented as fields. If the type has no fields, or does not fit
|
into one of these categories, an empty list will be returned.
|
See <a href="#Fields-of-a-type-in-Guile">Fields of a type in Guile</a>.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-make_002dfield_002diterator"></a>Scheme Procedure: <strong>make-field-iterator</strong> <em>type</em></dt>
|
<dd><p>Return the fields of <var>type</var> as a <gdb:iterator> object.
|
See <a href="Iterators-In-Guile.html#Iterators-In-Guile">Iterators In Guile</a>.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-type_002dfield"></a>Scheme Procedure: <strong>type-field</strong> <em>type field-name</em></dt>
|
<dd><p>Return field named <var>field-name</var> in <var>type</var>.
|
The result is an object of type <code><gdb:field></code>.
|
See <a href="#Fields-of-a-type-in-Guile">Fields of a type in Guile</a>.
|
If the type does not have fields, or <var>field-name</var> is not a field
|
of <var>type</var>, an exception is thrown.
|
</p>
|
<p>For example, if <code>some-type</code> is a <code><gdb:type></code> instance holding
|
a structure type, you can access its <code>foo</code> field with:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(define bar (type-field some-type "foo"))
|
</pre></div>
|
|
<p><code>bar</code> will be a <code><gdb:field></code> object.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-type_002dhas_002dfield_003f"></a>Scheme Procedure: <strong>type-has-field?</strong> <em>type name</em></dt>
|
<dd><p>Return <code>#t</code> if <code><gdb:type></code> <var>type</var> has field named <var>name</var>.
|
Otherwise return <code>#f</code>.
|
</p></dd></dl>
|
|
<p>Each type has a code, which indicates what category this type falls
|
into. The available type categories are represented by constants
|
defined in the <code>(gdb)</code> module:
|
</p>
|
<dl compact="compact">
|
<dt><code>TYPE_CODE_PTR</code>
|
<a name="index-TYPE_005fCODE_005fPTR-1"></a>
|
</dt>
|
<dd><p>The type is a pointer.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_ARRAY</code>
|
<a name="index-TYPE_005fCODE_005fARRAY-1"></a>
|
</dt>
|
<dd><p>The type is an array.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_STRUCT</code>
|
<a name="index-TYPE_005fCODE_005fSTRUCT-1"></a>
|
</dt>
|
<dd><p>The type is a structure.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_UNION</code>
|
<a name="index-TYPE_005fCODE_005fUNION-1"></a>
|
</dt>
|
<dd><p>The type is a union.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_ENUM</code>
|
<a name="index-TYPE_005fCODE_005fENUM-1"></a>
|
</dt>
|
<dd><p>The type is an enum.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_FLAGS</code>
|
<a name="index-TYPE_005fCODE_005fFLAGS-1"></a>
|
</dt>
|
<dd><p>A bit flags type, used for things such as status registers.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_FUNC</code>
|
<a name="index-TYPE_005fCODE_005fFUNC-1"></a>
|
</dt>
|
<dd><p>The type is a function.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_INT</code>
|
<a name="index-TYPE_005fCODE_005fINT-1"></a>
|
</dt>
|
<dd><p>The type is an integer type.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_FLT</code>
|
<a name="index-TYPE_005fCODE_005fFLT-1"></a>
|
</dt>
|
<dd><p>A floating point type.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_VOID</code>
|
<a name="index-TYPE_005fCODE_005fVOID-1"></a>
|
</dt>
|
<dd><p>The special type <code>void</code>.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_SET</code>
|
<a name="index-TYPE_005fCODE_005fSET-1"></a>
|
</dt>
|
<dd><p>A Pascal set type.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_RANGE</code>
|
<a name="index-TYPE_005fCODE_005fRANGE-1"></a>
|
</dt>
|
<dd><p>A range type, that is, an integer type with bounds.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_STRING</code>
|
<a name="index-TYPE_005fCODE_005fSTRING-1"></a>
|
</dt>
|
<dd><p>A string type. Note that this is only used for certain languages with
|
language-defined string types; C strings are not represented this way.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_BITSTRING</code>
|
<a name="index-TYPE_005fCODE_005fBITSTRING-1"></a>
|
</dt>
|
<dd><p>A string of bits. It is deprecated.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_ERROR</code>
|
<a name="index-TYPE_005fCODE_005fERROR-1"></a>
|
</dt>
|
<dd><p>An unknown or erroneous type.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_METHOD</code>
|
<a name="index-TYPE_005fCODE_005fMETHOD-1"></a>
|
</dt>
|
<dd><p>A method type, as found in C<tt>++</tt>.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_METHODPTR</code>
|
<a name="index-TYPE_005fCODE_005fMETHODPTR-1"></a>
|
</dt>
|
<dd><p>A pointer-to-member-function.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_MEMBERPTR</code>
|
<a name="index-TYPE_005fCODE_005fMEMBERPTR-1"></a>
|
</dt>
|
<dd><p>A pointer-to-member.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_REF</code>
|
<a name="index-TYPE_005fCODE_005fREF-1"></a>
|
</dt>
|
<dd><p>A reference type.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_CHAR</code>
|
<a name="index-TYPE_005fCODE_005fCHAR-1"></a>
|
</dt>
|
<dd><p>A character type.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_BOOL</code>
|
<a name="index-TYPE_005fCODE_005fBOOL-1"></a>
|
</dt>
|
<dd><p>A boolean type.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_COMPLEX</code>
|
<a name="index-TYPE_005fCODE_005fCOMPLEX-1"></a>
|
</dt>
|
<dd><p>A complex float type.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_TYPEDEF</code>
|
<a name="index-TYPE_005fCODE_005fTYPEDEF-1"></a>
|
</dt>
|
<dd><p>A typedef to some other type.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_NAMESPACE</code>
|
<a name="index-TYPE_005fCODE_005fNAMESPACE-1"></a>
|
</dt>
|
<dd><p>A C<tt>++</tt> namespace.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_DECFLOAT</code>
|
<a name="index-TYPE_005fCODE_005fDECFLOAT-1"></a>
|
</dt>
|
<dd><p>A decimal floating point type.
|
</p>
|
</dd>
|
<dt><code>TYPE_CODE_INTERNAL_FUNCTION</code>
|
<a name="index-TYPE_005fCODE_005fINTERNAL_005fFUNCTION-1"></a>
|
</dt>
|
<dd><p>A function internal to <small>GDB</small>. This is the type used to represent
|
convenience functions (see <a href="Convenience-Funs.html#Convenience-Funs">Convenience Funs</a>).
|
</p></dd>
|
</dl>
|
|
<p>Further support for types is provided in the <code>(gdb types)</code>
|
Guile module (see <a href="Guile-Types-Module.html#Guile-Types-Module">Guile Types Module</a>).
|
</p>
|
<a name="Fields-of-a-type-in-Guile"></a><p>Each field is represented as an object of type <code><gdb:field></code>.
|
</p>
|
<p>The following field-related procedures are provided by the
|
<code>(gdb)</code> module:
|
</p>
|
<dl>
|
<dt><a name="index-field_003f"></a>Scheme Procedure: <strong>field?</strong> <em>object</em></dt>
|
<dd><p>Return <code>#t</code> if <var>object</var> is an object of type <code><gdb:field></code>.
|
Otherwise return <code>#f</code>.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-field_002dname"></a>Scheme Procedure: <strong>field-name</strong> <em>field</em></dt>
|
<dd><p>Return the name of the field, or <code>#f</code> for anonymous fields.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-field_002dtype"></a>Scheme Procedure: <strong>field-type</strong> <em>field</em></dt>
|
<dd><p>Return the type of the field. This is usually an instance of
|
<code><gdb:type></code>, but it can be <code>#f</code> in some situations.
|
</p></dd></dl>
|
|
<dl>
|
<dt><a name="index-field_002denumval"></a>Scheme Procedure: <strong>field-enumval</strong> <em>field</em></dt>
|
<dd><p>Return the enum value represented by <code><gdb:field></code> <var>field</var>.
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</p></dd></dl>
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<dl>
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<dt><a name="index-field_002dbitpos"></a>Scheme Procedure: <strong>field-bitpos</strong> <em>field</em></dt>
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<dd><p>Return the bit position of <code><gdb:field></code> <var>field</var>.
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This attribute is not available for <code>static</code> fields (as in
|
C<tt>++</tt>).
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</p></dd></dl>
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<dl>
|
<dt><a name="index-field_002dbitsize"></a>Scheme Procedure: <strong>field-bitsize</strong> <em>field</em></dt>
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<dd><p>If the field is packed, or is a bitfield, return the size of
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<code><gdb:field></code> <var>field</var> in bits. Otherwise, zero is returned;
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in which case the field’s size is given by its type.
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</p></dd></dl>
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<dl>
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<dt><a name="index-field_002dartificial_003f"></a>Scheme Procedure: <strong>field-artificial?</strong> <em>field</em></dt>
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<dd><p>Return <code>#t</code> if the field is artificial, usually meaning that
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it was provided by the compiler and not the user.
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Otherwise return <code>#f</code>.
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</p></dd></dl>
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<dl>
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<dt><a name="index-field_002dbase_002dclass_003f"></a>Scheme Procedure: <strong>field-base-class?</strong> <em>field</em></dt>
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<dd><p>Return <code>#t</code> if the field represents a base class of a C<tt>++</tt>
|
structure.
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Otherwise return <code>#f</code>.
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</p></dd></dl>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Guile-Pretty-Printing-API.html#Guile-Pretty-Printing-API" accesskey="n" rel="next">Guile Pretty Printing API</a>, Previous: <a href="Arithmetic-In-Guile.html#Arithmetic-In-Guile" accesskey="p" rel="previous">Arithmetic In Guile</a>, Up: <a href="Guile-API.html#Guile-API" accesskey="u" rel="up">Guile 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>
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