| <!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: Parameters In Guile</title> |
| |
| <meta name="description" content="Debugging with GDB: Parameters In Guile"> |
| <meta name="keywords" content="Debugging with GDB: Parameters In Guile"> |
| <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="Guile-API.html#Guile-API" rel="up" title="Guile API"> |
| <link href="Progspaces-In-Guile.html#Progspaces-In-Guile" rel="next" title="Progspaces In Guile"> |
| <link href="Commands-In-Guile.html#Commands-In-Guile" rel="prev" title="Commands In Guile"> |
| <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="Parameters-In-Guile"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="Progspaces-In-Guile.html#Progspaces-In-Guile" accesskey="n" rel="next">Progspaces In Guile</a>, Previous: <a href="Commands-In-Guile.html#Commands-In-Guile" accesskey="p" rel="prev">Commands 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="Parameters-In-Guile-1"></a> |
| <h4 class="subsubsection">23.3.3.12 Parameters In Guile</h4> |
| |
| <a name="index-parameters-in-guile"></a> |
| <a name="index-guile-parameters"></a> |
| <a name="index-Parameter-1"></a> |
| <p>You can implement new <small>GDB</small> <em>parameters</em> using Guile |
| <a name="DOCF17" href="#FOOT17"><sup>17</sup></a>. |
| </p> |
| <p>There are many parameters that already exist and can be set in |
| <small>GDB</small>. Two examples are: <code>set follow-fork</code> and |
| <code>set charset</code>. Setting these parameters influences certain |
| behavior in <small>GDB</small>. Similarly, you can define parameters that |
| can be used to influence behavior in custom Guile scripts and commands. |
| </p> |
| <p>A new parameter is defined with the <code>make-parameter</code> Guile function, |
| and added to <small>GDB</small> with the <code>register-parameter!</code> Guile function. |
| This two-step approach is taken to separate out the side-effect of adding |
| the parameter to <small>GDB</small> from <code>make-parameter</code>. |
| </p> |
| <p>Parameters are exposed to the user via the <code>set</code> and |
| <code>show</code> commands. See <a href="Help.html#Help">Help</a>. |
| </p> |
| <dl> |
| <dt><a name="index-_0028make_002dparameter"></a>Scheme Procedure: <strong>(make-parameter</strong> <em>name <span class="roman">[</span>#:command-class command-class<span class="roman">]</span> <span class="roman">[</span>#:parameter-type parameter-type] <span class="roman">[</span>#:enum-list enum-list<span class="roman">]</span> <span class="roman">[</span>#:set-func set-func] <span class="roman">[</span>#:show-func show-func] <span class="roman">[</span>#:doc doc] <span class="roman">[</span>#:set-doc set-doc] <span class="roman">[</span>#:show-doc show-doc] <span class="roman">[</span>#:initial-value initial-value])</em></dt> |
| <dd> |
| <p>The argument <var>name</var> is the name of the new parameter. If <var>name</var> |
| consists of multiple words, then the initial words are looked for as prefix |
| parameters. An example of this can be illustrated with the |
| <code>set print</code> set of parameters. If <var>name</var> is |
| <code>print foo</code>, then <code>print</code> will be searched as the prefix |
| parameter. In this case the parameter can subsequently be accessed in |
| <small>GDB</small> as <code>set print foo</code>. |
| If <var>name</var> consists of multiple words, and no prefix parameter group |
| can be found, an exception is raised. |
| </p> |
| <p>The result is the <code><gdb:parameter></code> object representing the parameter. |
| The parameter is not usable until it has been registered with <small>GDB</small> |
| with <code>register-parameter!</code>. |
| </p> |
| <p>The rest of the arguments are optional. |
| </p> |
| <p>The argument <var>command-class</var> should be one of the ‘<samp>COMMAND_</samp>’ constants |
| (see <a href="Commands-In-Guile.html#Commands-In-Guile">Commands In Guile</a>). This argument tells <small>GDB</small> how to |
| categorize the new parameter in the help system. |
| The default is <code>COMMAND_NONE</code>. |
| </p> |
| <p>The argument <var>parameter-type</var> should be one of the ‘<samp>PARAM_</samp>’ constants |
| defined below. This argument tells <small>GDB</small> the type of the new |
| parameter; this information is used for input validation and |
| completion. The default is <code>PARAM_BOOLEAN</code>. |
| </p> |
| <p>If <var>parameter-type</var> is <code>PARAM_ENUM</code>, then |
| <var>enum-list</var> must be a list of strings. These strings |
| represent the possible values for the parameter. |
| </p> |
| <p>If <var>parameter-type</var> is not <code>PARAM_ENUM</code>, then the presence |
| of <var>enum-list</var> will cause an exception to be thrown. |
| </p> |
| <p>The argument <var>set-func</var> is a function of one argument: <var>self</var> which |
| is the <code><gdb:parameter></code> object representing the parameter. |
| <small>GDB</small> will call this function when a <var>parameter</var>’s value has |
| been changed via the <code>set</code> API (for example, <kbd>set foo off</kbd>). |
| The value of the parameter has already been set to the new value. |
| This function must return a string to be displayed to the user. |
| <small>GDB</small> will add a trailing newline if the string is non-empty. |
| <small>GDB</small> generally doesn’t print anything when a parameter is set, |
| thus typically this function should return ‘<samp>""</samp>’. |
| A non-empty string result should typically be used for displaying warnings |
| and errors. |
| </p> |
| <p>The argument <var>show-func</var> is a function of two arguments: <var>self</var> which |
| is the <code><gdb:parameter></code> object representing the parameter, and |
| <var>svalue</var> which is the string representation of the current value. |
| <small>GDB</small> will call this function when a <var>parameter</var>’s |
| <code>show</code> API has been invoked (for example, <kbd>show foo</kbd>). |
| This function must return a string, and will be displayed to the user. |
| <small>GDB</small> will add a trailing newline. |
| </p> |
| <p>The argument <var>doc</var> is the help text for the new parameter. |
| If there is no documentation string, a default value is used. |
| </p> |
| <p>The argument <var>set-doc</var> is the help text for this parameter’s |
| <code>set</code> command. |
| </p> |
| <p>The argument <var>show-doc</var> is the help text for this parameter’s |
| <code>show</code> command. |
| </p> |
| <p>The argument <var>initial-value</var> specifies the initial value of the parameter. |
| If it is a function, it takes one parameter, the <code><gdb:parameter></code> |
| object and its result is used as the initial value of the parameter. |
| The initial value must be valid for the parameter type, |
| otherwise an exception is thrown. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-register_002dparameter_0021"></a>Scheme Procedure: <strong>register-parameter!</strong> <em>parameter</em></dt> |
| <dd><p>Add <var>parameter</var>, a <code><gdb:parameter></code> object, to <small>GDB</small>’s |
| list of parameters. |
| It is an error to register a parameter more than once. |
| The result is unspecified. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-parameter_003f"></a>Scheme Procedure: <strong>parameter?</strong> <em>object</em></dt> |
| <dd><p>Return <code>#t</code> if <var>object</var> is a <code><gdb:parameter></code> object. |
| Otherwise return <code>#f</code>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-parameter_002dvalue"></a>Scheme Procedure: <strong>parameter-value</strong> <em>parameter</em></dt> |
| <dd><p>Return the value of <var>parameter</var> which may either be |
| a <code><gdb:parameter></code> object or a string naming the parameter. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-set_002dparameter_002dvalue_0021"></a>Scheme Procedure: <strong>set-parameter-value!</strong> <em>parameter new-value</em></dt> |
| <dd><p>Assign <var>parameter</var> the value of <var>new-value</var>. |
| The argument <var>parameter</var> must be an object of type <code><gdb:parameter></code>. |
| <small>GDB</small> does validation when assignments are made. |
| </p></dd></dl> |
| |
| <p>When a new parameter is defined, its type must be specified. The |
| available types are represented by constants defined in the <code>gdb</code> |
| module: |
| </p> |
| <dl compact="compact"> |
| <dt><code>PARAM_BOOLEAN</code> |
| <a name="index-PARAM_005fBOOLEAN-1"></a> |
| </dt> |
| <dd><p>The value is a plain boolean. The Guile boolean values, <code>#t</code> |
| and <code>#f</code> are the only valid values. |
| </p> |
| </dd> |
| <dt><code>PARAM_AUTO_BOOLEAN</code> |
| <a name="index-PARAM_005fAUTO_005fBOOLEAN-1"></a> |
| </dt> |
| <dd><p>The value has three possible states: true, false, and ‘<samp>auto</samp>’. In |
| Guile, true and false are represented using boolean constants, and |
| ‘<samp>auto</samp>’ is represented using <code>#:auto</code>. |
| </p> |
| </dd> |
| <dt><code>PARAM_UINTEGER</code> |
| <a name="index-PARAM_005fUINTEGER-1"></a> |
| </dt> |
| <dd><p>The value is an unsigned integer. The value of 0 should be |
| interpreted to mean “unlimited”. |
| </p> |
| </dd> |
| <dt><code>PARAM_ZINTEGER</code> |
| <a name="index-PARAM_005fZINTEGER-1"></a> |
| </dt> |
| <dd><p>The value is an integer. |
| </p> |
| </dd> |
| <dt><code>PARAM_ZUINTEGER</code> |
| <a name="index-PARAM_005fZUINTEGER"></a> |
| </dt> |
| <dd><p>The value is an unsigned integer. |
| </p> |
| </dd> |
| <dt><code>PARAM_ZUINTEGER_UNLIMITED</code> |
| <a name="index-PARAM_005fZUINTEGER_005fUNLIMITED"></a> |
| </dt> |
| <dd><p>The value is an integer in the range ‘<samp>[0, INT_MAX]</samp>’. |
| A value of ‘<samp>-1</samp>’ means “unlimited”, and other negative |
| numbers are not allowed. |
| </p> |
| </dd> |
| <dt><code>PARAM_STRING</code> |
| <a name="index-PARAM_005fSTRING-1"></a> |
| </dt> |
| <dd><p>The value is a string. When the user modifies the string, any escape |
| sequences, such as ‘<samp>\t</samp>’, ‘<samp>\f</samp>’, and octal escapes, are |
| translated into corresponding characters and encoded into the current |
| host charset. |
| </p> |
| </dd> |
| <dt><code>PARAM_STRING_NOESCAPE</code> |
| <a name="index-PARAM_005fSTRING_005fNOESCAPE-1"></a> |
| </dt> |
| <dd><p>The value is a string. When the user modifies the string, escapes are |
| passed through untranslated. |
| </p> |
| </dd> |
| <dt><code>PARAM_OPTIONAL_FILENAME</code> |
| <a name="index-PARAM_005fOPTIONAL_005fFILENAME-1"></a> |
| </dt> |
| <dd><p>The value is a either a filename (a string), or <code>#f</code>. |
| </p> |
| </dd> |
| <dt><code>PARAM_FILENAME</code> |
| <a name="index-PARAM_005fFILENAME-1"></a> |
| </dt> |
| <dd><p>The value is a filename. This is just like |
| <code>PARAM_STRING_NOESCAPE</code>, but uses file names for completion. |
| </p> |
| </dd> |
| <dt><code>PARAM_ENUM</code> |
| <a name="index-PARAM_005fENUM-1"></a> |
| </dt> |
| <dd><p>The value is a string, which must be one of a collection of string |
| constants provided when the parameter is created. |
| </p></dd> |
| </dl> |
| |
| <div class="footnote"> |
| <hr> |
| <h4 class="footnotes-heading">Footnotes</h4> |
| |
| <h3><a name="FOOT17" href="#DOCF17">(17)</a></h3> |
| <p>Note that <small>GDB</small> parameters must not be confused with |
| Guileâs parameter objects (see <a href="http://www.gnu.org/software/guile/manual/html_node/Parameters.html#Parameters">Parameters</a> in <cite>GNU Guile |
| Reference Manual</cite>).</p> |
| </div> |
| <hr> |
| <div class="header"> |
| <p> |
| Next: <a href="Progspaces-In-Guile.html#Progspaces-In-Guile" accesskey="n" rel="next">Progspaces In Guile</a>, Previous: <a href="Commands-In-Guile.html#Commands-In-Guile" accesskey="p" rel="prev">Commands 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> |
| |
| |
| |
| </body> |
| </html> |
