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| <title>Debugging with GDB: Symbols In Guile</title> |
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| <a name="Symbols-In-Guile"></a> |
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| <p> |
| Next: <a href="Symbol-Tables-In-Guile.html#Symbol-Tables-In-Guile" accesskey="n" rel="next">Symbol Tables In Guile</a>, Previous: <a href="Blocks-In-Guile.html#Blocks-In-Guile" accesskey="p" rel="prev">Blocks 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> |
| </div> |
| <hr> |
| <a name="Guile-representation-of-Symbols_002e"></a> |
| <h4 class="subsubsection">23.3.3.17 Guile representation of Symbols.</h4> |
| |
| <a name="index-symbols-in-guile"></a> |
| <a name="index-_003cgdb_003asymbol_003e"></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>. |
| Guile represents these symbols in <small>GDB</small> with the |
| <code><gdb:symbol></code> object. |
| </p> |
| <p>The following symbol-related procedures are provided by the |
| <code>(gdb)</code> module: |
| </p> |
| <dl> |
| <dt><a name="index-symbol_003f"></a>Scheme Procedure: <strong>symbol?</strong> <em>object</em></dt> |
| <dd><p>Return <code>#t</code> if <var>object</var> is an object of type <code><gdb:symbol></code>. |
| Otherwise return <code>#f</code>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dvalid_003f"></a>Scheme Procedure: <strong>symbol-valid?</strong> <em>symbol</em></dt> |
| <dd><p>Return <code>#t</code> if the <code><gdb:symbol></code> object is valid, |
| <code>#f</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> procedures will throw an exception if it is |
| invalid at the time the procedure is called. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dtype"></a>Scheme Procedure: <strong>symbol-type</strong> <em>symbol</em></dt> |
| <dd><p>Return the type of <var>symbol</var> or <code>#f</code> if no type is recorded. |
| The result is an object of type <code><gdb:type></code>. |
| See <a href="Types-In-Guile.html#Types-In-Guile">Types In Guile</a>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dsymtab"></a>Scheme Procedure: <strong>symbol-symtab</strong> <em>symbol</em></dt> |
| <dd><p>Return the symbol table in which <var>symbol</var> appears. |
| The result is an object of type <code><gdb:symtab></code>. |
| See <a href="Symbol-Tables-In-Guile.html#Symbol-Tables-In-Guile">Symbol Tables In Guile</a>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dline"></a>Scheme Procedure: <strong>symbol-line</strong> <em>symbol</em></dt> |
| <dd><p>Return the line number in the source code at which <var>symbol</var> was defined. |
| This is an integer. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dname"></a>Scheme Procedure: <strong>symbol-name</strong> <em>symbol</em></dt> |
| <dd><p>Return the name of <var>symbol</var> as a string. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dlinkage_002dname"></a>Scheme Procedure: <strong>symbol-linkage-name</strong> <em>symbol</em></dt> |
| <dd><p>Return the name of <var>symbol</var>, as used by the linker (i.e., may be mangled). |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dprint_002dname"></a>Scheme Procedure: <strong>symbol-print-name</strong> <em>symbol</em></dt> |
| <dd><p>Return the name of <var>symbol</var> 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_002daddr_002dclass"></a>Scheme Procedure: <strong>symbol-addr-class</strong> <em>symbol</em></dt> |
| <dd><p>Return 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_002dneeds_002dframe_003f"></a>Scheme Procedure: <strong>symbol-needs-frame?</strong> <em>symbol</em></dt> |
| <dd><p>Return <code>#t</code> if evaluating <var>symbol</var>’s value requires a frame |
| (see <a href="Frames-In-Guile.html#Frames-In-Guile">Frames In Guile</a>) and <code>#f</code> otherwise. Typically, |
| local variables will require a frame, but other symbols will not. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dargument_003f"></a>Scheme Procedure: <strong>symbol-argument?</strong> <em>symbol</em></dt> |
| <dd><p>Return <code>#t</code> if <var>symbol</var> is an argument of a function. |
| Otherwise return <code>#f</code>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dconstant_003f"></a>Scheme Procedure: <strong>symbol-constant?</strong> <em>symbol</em></dt> |
| <dd><p>Return <code>#t</code> if <var>symbol</var> is a constant. |
| Otherwise return <code>#f</code>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dfunction_003f"></a>Scheme Procedure: <strong>symbol-function?</strong> <em>symbol</em></dt> |
| <dd><p>Return <code>#t</code> if <var>symbol</var> is a function or a method. |
| Otherwise return <code>#f</code>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dvariable_003f"></a>Scheme Procedure: <strong>symbol-variable?</strong> <em>symbol</em></dt> |
| <dd><p>Return <code>#t</code> if <var>symbol</var> is a variable. |
| Otherwise return <code>#f</code>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-symbol_002dvalue"></a>Scheme Procedure: <strong>symbol-value</strong> <em>symbol <span class="roman">[</span>#:frame frame<span class="roman">]</span></em></dt> |
| <dd><p>Compute the value of <var>symbol</var>, 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 an exception is thrown. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-lookup_002dsymbol"></a>Scheme Procedure: <strong>lookup-symbol</strong> <em>name <span class="roman">[</span>#:block block<span class="roman">]</span> <span class="roman">[</span>#:domain 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 list of two elements. |
| The first element is a <code><gdb:symbol></code> object or <code>#f</code> if the symbol |
| is not found. |
| If the symbol is found, the second element is <code>#t</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>#f</code>. |
| If the symbol is not found, the second element is <code>#f</code>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-lookup_002dglobal_002dsymbol"></a>Scheme Procedure: <strong>lookup-global-symbol</strong> <em>name <span class="roman">[</span>#:domain domain<span class="roman">]</span></em></dt> |
| <dd><p>This function searches for a global symbol by name. |
| The search scope can be restricted 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>#f</code> if the symbol |
| is not found. |
| </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"> |
| <dt><code>SYMBOL_UNDEF_DOMAIN</code> |
| <a name="index-SYMBOL_005fUNDEF_005fDOMAIN-1"></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> |
| </dd> |
| <dt><code>SYMBOL_VAR_DOMAIN</code> |
| <a name="index-SYMBOL_005fVAR_005fDOMAIN-1"></a> |
| </dt> |
| <dd><p>This domain contains variables, function names, typedef names and enum |
| type values. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_STRUCT_DOMAIN</code> |
| <a name="index-SYMBOL_005fSTRUCT_005fDOMAIN-1"></a> |
| </dt> |
| <dd><p>This domain holds struct, union and enum type names. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_LABEL_DOMAIN</code> |
| <a name="index-SYMBOL_005fLABEL_005fDOMAIN-1"></a> |
| </dt> |
| <dd><p>This domain contains names of labels (for gotos). |
| </p> |
| </dd> |
| <dt><code>SYMBOL_VARIABLES_DOMAIN</code> |
| <a name="index-SYMBOL_005fVARIABLES_005fDOMAIN-1"></a> |
| </dt> |
| <dd><p>This domain holds a subset of the <code>SYMBOLS_VAR_DOMAIN</code>; it |
| contains everything minus functions and types. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_FUNCTION_DOMAIN</code> |
| <a name="index-SYMBOL_005fFUNCTION_005fDOMAIN"></a> |
| </dt> |
| <dd><p>This domain contains all functions. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_TYPES_DOMAIN</code> |
| <a name="index-SYMBOL_005fTYPES_005fDOMAIN-1"></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"> |
| <dt><code>SYMBOL_LOC_UNDEF</code> |
| <a name="index-SYMBOL_005fLOC_005fUNDEF-1"></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> |
| </dd> |
| <dt><code>SYMBOL_LOC_CONST</code> |
| <a name="index-SYMBOL_005fLOC_005fCONST-1"></a> |
| </dt> |
| <dd><p>Value is constant int. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_LOC_STATIC</code> |
| <a name="index-SYMBOL_005fLOC_005fSTATIC-1"></a> |
| </dt> |
| <dd><p>Value is at a fixed address. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_LOC_REGISTER</code> |
| <a name="index-SYMBOL_005fLOC_005fREGISTER-1"></a> |
| </dt> |
| <dd><p>Value is in a register. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_LOC_ARG</code> |
| <a name="index-SYMBOL_005fLOC_005fARG-1"></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> |
| </dd> |
| <dt><code>SYMBOL_LOC_REF_ARG</code> |
| <a name="index-SYMBOL_005fLOC_005fREF_005fARG-1"></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> |
| </dd> |
| <dt><code>SYMBOL_LOC_REGPARM_ADDR</code> |
| <a name="index-SYMBOL_005fLOC_005fREGPARM_005fADDR-1"></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> |
| </dd> |
| <dt><code>SYMBOL_LOC_LOCAL</code> |
| <a name="index-SYMBOL_005fLOC_005fLOCAL-1"></a> |
| </dt> |
| <dd><p>Value is a local variable. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_LOC_TYPEDEF</code> |
| <a name="index-SYMBOL_005fLOC_005fTYPEDEF-1"></a> |
| </dt> |
| <dd><p>Value not used. Symbols in the domain <code>SYMBOL_STRUCT_DOMAIN</code> all |
| have this class. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_LOC_BLOCK</code> |
| <a name="index-SYMBOL_005fLOC_005fBLOCK-1"></a> |
| </dt> |
| <dd><p>Value is a block. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_LOC_CONST_BYTES</code> |
| <a name="index-SYMBOL_005fLOC_005fCONST_005fBYTES-1"></a> |
| </dt> |
| <dd><p>Value is a byte-sequence. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_LOC_UNRESOLVED</code> |
| <a name="index-SYMBOL_005fLOC_005fUNRESOLVED-1"></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> |
| </dd> |
| <dt><code>SYMBOL_LOC_OPTIMIZED_OUT</code> |
| <a name="index-SYMBOL_005fLOC_005fOPTIMIZED_005fOUT-1"></a> |
| </dt> |
| <dd><p>The value does not actually exist in the program. |
| </p> |
| </dd> |
| <dt><code>SYMBOL_LOC_COMPUTED</code> |
| <a name="index-SYMBOL_005fLOC_005fCOMPUTED-1"></a> |
| </dt> |
| <dd><p>The value’s address is a computed location. |
| </p></dd> |
| </dl> |
| |
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| Next: <a href="Symbol-Tables-In-Guile.html#Symbol-Tables-In-Guile" accesskey="n" rel="next">Symbol Tables In Guile</a>, Previous: <a href="Blocks-In-Guile.html#Blocks-In-Guile" accesskey="p" rel="prev">Blocks 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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