boost-react-native-bundle

<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Overview</title> <link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../bbv2.html" title="Chapter 43. Boost.Build V2 User Manual"> <link rel="prev" href="tutorial.html" title="Tutorial"> <link rel="next" href="tasks.html" title="Common tasks"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> <td align="center"><a href="../../../index.html">Home</a></td> <td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="tutorial.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../bbv2.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="tasks.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="section"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="bbv2.overview"></a>Overview</h2></div></div></div> <div class="toc"><dl class="toc"> <dt><span class="section"><a href="overview.html#bbv2.overview.concepts">Concepts</a></span></dt> <dt><span class="section"><a href="overview.html#bbv2.overview.jam_language">Boost.Jam Language</a></span></dt> <dt><span class="section"><a href="overview.html#bbv2.overview.configuration">Configuration</a></span></dt> <dt><span class="section"><a href="overview.html#bbv2.overview.invocation">Invocation</a></span></dt> <dt><span class="section"><a href="overview.html#bbv2.overview.targets">Declaring Targets</a></span></dt> <dt><span class="section"><a href="overview.html#bbv2.overview.projects">Projects</a></span></dt> <dt><span class="section"><a href="overview.html#bbv2.overview.build_process">The Build Process</a></span></dt> </dl></div> <p> This section will provide the information necessary to create your own projects using Boost.Build. The information provided here is relatively high-level, and <a class="xref" href="reference.html" title="Reference">the section called “Reference”</a> as well as the on-line help system must be used to obtain low-level documentation (see <a class="xref" href="overview.html#bbv2.reference.init.options.help"><code class="option">--help</code></a>). </p> <p> Boost.Build has two parts—a build engine with its own interpreted language, and Boost.Build itself, implemented in that language. The chain of events when you type <span class="command"><strong>b2</strong></span> on the command line is as follows: </p> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem"><p> The Boost.Build executable tries to find Boost.Build modules and loads the top-level module. The exact process is described in <a class="xref" href="reference.html#bbv2.reference.init" title="Initialization">the section called “Initialization”</a> </p></li> <li class="listitem"><p> The top-level module loads user-defined configuration files, <code class="filename">user-config.jam</code> and <code class="filename">site-config.jam</code>, which define available toolsets. </p></li> <li class="listitem"><p> The Jamfile in the current directory is read. That in turn might cause reading of further Jamfiles. As a result, a tree of projects is created, with targets inside projects. </p></li> <li class="listitem"><p> Finally, using the build request specified on the command line, Boost.Build decides which targets should be built and how. That information is passed back to Boost.Jam, which takes care of actually running the scheduled build action commands. </p></li> </ol></div> <p> </p> <p> So, to be able to successfully use Boost.Build, you need to know only four things: </p> <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"><p> <a class="link" href="overview.html#bbv2.overview.configuration" title="Configuration">How to configure Boost.Build</a> </p></li> <li class="listitem"><p> <a class="link" href="overview.html#bbv2.overview.targets" title="Declaring Targets">How to declare targets in Jamfiles</a> </p></li> <li class="listitem"><p> <a class="link" href="overview.html#bbv2.overview.build_process" title="The Build Process">How the build process works</a> </p></li> <li class="listitem"><p> Some Basics about the Boost.Jam language. See <a class="xref" href="overview.html#bbv2.overview.jam_language" title="Boost.Jam Language">the section called “Boost.Jam Language”</a>. </p></li> </ul></div> <p> </p> <div class="section"> <div class="titlepage"><div><div><h3 class="title"> <a name="bbv2.overview.concepts"></a>Concepts</h3></div></div></div> <p>Boost.Build has a few unique concepts that are introduced in this section. The best way to explain the concepts is by comparison with more classical build tools.</p> <p> When using any flavour of make, you directly specify <em class="firstterm">targets</em> and commands that are used to create them from other target. The below example creates <code class="filename">a.o</code> from <code class="filename">a.c</code> using a hardcoded compiler invocation command. </p> <pre class="programlisting"> a.o: a.c g++ -o a.o -g a.c </pre> <p> This is a rather low-level description mechanism and it's hard to adjust commands, options, and sets of created targets depending on the compiler and operating system used. </p> <p> To improve portability, most modern build system provide a set of higher-level functions that can be used in build description files. Consider this example: </p> <pre class="programlisting"> add_program ("a", "a.c") </pre> <p> This is a function call that creates the targets necessary to create a executable file from the source file <code class="filename">a.c</code>. Depending on configured properties, different command lines may be used. However, <code class="computeroutput">add_program</code> is higher-level, but rather thin level. All targets are created immediately when the build description is parsed, which makes it impossible to perform multi-variant builds. Often, change in any build property requires a complete reconfiguration of the build tree. </p> <p> In order to support true multivariant builds, Boost.Build introduces the concept of a <a class="indexterm" name="idp547395600"></a> <a class="indexterm" name="idp547396960"></a> <em class="firstterm">metatarget</em>—an object that is created when the build description is parsed and can be called later with specific build properties to generate actual targets. </p> <p> Consider an example: </p> <pre class="programlisting"> exe a : a.cpp ; </pre> <p> When this declaration is parsed, Boost.Build creates a metatarget, but does not yet decide what files must be created, or what commands must be used. After all build files are parsed, Boost.Build considers the properties requested on the command line. Supposed you have invoked Boost.Build with: </p> <pre class="screen"> b2 toolset=gcc toolset=msvc </pre> <p> In that case, the metatarget will be called twice, once with <code class="computeroutput">toolset=gcc</code> and once with <code class="computeroutput">toolset=msvc</code>. Both invocations will produce concrete targets, that will have different extensions and use different command lines. </p> <p> Another key concept is <a class="indexterm" name="idp547403312"></a> <em class="firstterm">build property</em>. A build property is a variable that affects the build process. It can be specified on the command line, and is passed when calling a metatarget. While all build tools have a similar mechanism, Boost.Build differs by requiring that all build properties are declared in advance, and providing a large set of properties with portable semantics. </p> <p> The final concept is <a class="indexterm" name="idp547405664"></a> <em class="firstterm">property propagation</em>. Boost.Build does not require that every metatarget is called with the same properties. Instead, the "top-level" metatargets are called with the properties specified on the command line. Each metatarget can elect to augment or override some properties (in particular, using the requirements mechanism, see <a class="xref" href="overview.html#bbv2.overview.targets.requirements" title="Requirements">the section called “Requirements”</a>). Then, the dependency metatargets are called with the modified properties and produce concrete targets that are then used in the build process. Of course, dependency metatargets maybe in turn modify build properties and have dependencies of their own. </p> <p>For a more in-depth treatment of the requirements and concepts, you may refer to <a href="http://syrcose.ispras.ru/2009/files/04_paper.pdf" target="_top">SYRCoSE 2009 Boost.Build article</a>. </p> </div> <div class="section"> <div class="titlepage"><div><div><h3 class="title"> <a name="bbv2.overview.jam_language"></a>Boost.Jam Language</h3></div></div></div> <p> This section will describe the basics of the Boost.Jam language—just enough for writing Jamfiles. For more information, please see the <a class="link" href="../">Boost.Jam</a> documentation. </p> <p> <a class="link" href="../">Boost.Jam</a> has an interpreted, procedural language. On the lowest level, a <a class="link" href="../">Boost.Jam </a> program consists of variables and <a class="indexterm" name="idp547415056"></a> <em class="firstterm">rules</em> (the Jam term for functions). They are grouped into modules—there is one global module and a number of named modules. Besides that, a <a class="link" href="../">Boost.Jam</a> program contains classes and class instances. </p> <p> Syntantically, a <a class="link" href="../">Boost.Jam</a> program consists of two kind of elements—keywords (which have a special meaning to <a class="link" href="../">Boost.Jam</a>) and literals. Consider this code: </p> <pre class="programlisting"> a = b ; </pre> <p> which assigns the value <code class="literal">b</code> to the variable <code class="literal">a </code>. Here, <code class="literal">=</code> and <code class="literal">;</code> are keywords, while <code class="literal">a</code> and <code class="literal">b</code> are literals. </p> <div class="warning"><table border="0" summary="Warning"> <tr> <td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td> <th align="left">Warning</th> </tr> <tr><td align="left" valign="top"><p> All syntax elements, even keywords, must be separated by spaces. For example, omitting the space character before <code class="literal">;</code> will lead to a syntax error. </p></td></tr> </table></div> <p> If you want to use a literal value that is the same as some keyword, the value can be quoted: </p> <pre class="programlisting"> a = "=" ; </pre> <p> </p> <p> All variables in <a class="link" href="../">Boost.Jam</a> have the same type—list of strings. To define a variable one assigns a value to it, like in the previous example. An undefined variable is the same as a variable with an empty value. Variables can be accessed using the <code class="computeroutput">$(<em class="replaceable"><code>variable</code></em>)</code> syntax. For example: </p> <pre class="programlisting"> a = $(b) $(c) ; </pre> <p> </p> <p> Rules are defined by specifying the rule name, the parameter names, and the allowed value list size for each parameter. </p> <pre class="programlisting"> rule <em class="replaceable"><code>example</code></em> ( <em class="replaceable"><code>parameter1</code></em> : <em class="replaceable"><code>parameter2 ?</code></em> : <em class="replaceable"><code>parameter3 +</code></em> : <em class="replaceable"><code>parameter4 *</code></em> ) { # rule body } </pre> <p> When this rule is called, the list passed as the first argument must have exactly one value. The list passed as the second argument can either have one value of be empty. The two remaining arguments can be arbitrarily long, but the third argument may not be empty. </p> <p> The overview of <a class="link" href="../">Boost.Jam</a> language statements is given below: </p> <pre class="programlisting"> helper 1 : 2 : 3 ; x = [ helper 1 : 2 : 3 ] ; </pre> <p> This code calls the named rule with the specified arguments. When the result of the call must be used inside some expression, you need to add brackets around the call, like shown on the second line. </p> <pre class="programlisting"> if cond { statements } [ else { statements } ] </pre> <p> This is a regular if-statement. The condition is composed of: </p> <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"><p> Literals (true if at least one string is not empty) </p></li> <li class="listitem"><p> Comparisons: <code class="computeroutput">a <em class="replaceable"><code>operator</code></em> b</code> where <em class="replaceable"><code>operator</code></em> is one of <code class="computeroutput">=</code>, <code class="computeroutput">!=</code>, <code class="computeroutput"><</code>, <code class="computeroutput">></code>, <code class="computeroutput"><=</code> or <code class="computeroutput">>=</code>. The comparison is done pairwise between each string in the left and the right arguments. </p></li> <li class="listitem"><p> Logical operations: <code class="computeroutput">! a</code>, <code class="computeroutput">a && b</code>, <code class="computeroutput">a || b</code> </p></li> <li class="listitem"><p> Grouping: <code class="computeroutput">( cond )</code> </p></li> </ul></div> <p> </p> <pre class="programlisting"> for var in list { statements } </pre> <p> Executes statements for each element in list, setting the variable <code class="varname">var</code> to the element value. </p> <pre class="programlisting"> while cond { statements } </pre> <p> Repeatedly execute statements while cond remains true upon entry. </p> <pre class="programlisting"> return values ; </pre> <p> This statement should be used only inside a rule and assigns <code class="computeroutput">values</code> to the return value of the rule. </p> <div class="warning"><table border="0" summary="Warning"> <tr> <td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td> <th align="left">Warning</th> </tr> <tr><td align="left" valign="top"> <p> The <code class="computeroutput">return</code> statement does not exit the rule. For example: </p> <pre class="programlisting"> rule test ( ) { if 1 = 1 { return "reasonable" ; } return "strange" ; } </pre> <p> will return <code class="literal">strange</code>, not <code class="literal">reasonable</code>. </p> </td></tr> </table></div> <p> </p> <pre class="programlisting"> import <em class="replaceable"><code>module</code></em> ; import <em class="replaceable"><code>module</code></em> : <em class="replaceable"><code>rule</code></em> ; </pre> <p> The first form imports the specified module. All rules from that module are made available using the qualified name: <code class="computeroutput"><em class="replaceable"><code> module</code></em>.<em class="replaceable"><code>rule</code></em></code>. The second form imports the specified rules only, and they can be called using unqualified names. </p> <p><a name="bbv2.overview.jam_language.actions"></a> Sometimes, you need to specify the actual command lines to be used when creating targets. In the jam language, you use named actions to do this. For example: </p> <pre class="programlisting"> actions create-file-from-another { create-file-from-another $(<) $(>) } </pre> <p> This specifies a named action called <code class="literal"> create-file-from-another</code>. The text inside braces is the command to invoke. The <code class="literal">$(<)</code> variable will be expanded to a list of generated files, and the <code class="literal">$(>) </code> variable will be expanded to a list of source files. </p> <p> To adjust the command line flexibly, you can define a rule with the same name as the action and taking three parameters—targets, sources and properties. For example: </p> <pre class="programlisting"> rule create-file-from-another ( targets * : sources * : properties * ) { if <variant>debug in $(properties) { OPTIONS on $(targets) = --debug ; } } actions create-file-from-another { create-file-from-another $(OPTIONS) $(<) $(>) } </pre> <p> In this example, the rule checks if a certain build property is specified. If so, it sets the variable <code class="varname">OPTIONS</code> that is then used inside the action. Note that the variables set "on a target" will be visible only inside actions building that target, not globally. Were they set globally, using variable named <code class="varname">OPTIONS</code> in two unrelated actions would be impossible. </p> <p> More details can be found in the Jam reference, <a class="xref" href="../jam/language.html#jam.language.rules" title="Rules">the section called “Rules”</a>. </p> </div> <div class="section"> <div class="titlepage"><div><div><h3 class="title"> <a name="bbv2.overview.configuration"></a>Configuration</h3></div></div></div> <p> On startup, Boost.Build searches and reads two configuration files: <code class="filename">site-config.jam</code> and <code class="filename">user-config.jam</code>. The first one is usually installed and maintained by a system administrator, and the second is for the user to modify. You can edit the one in the top-level directory of your Boost.Build installation or create a copy in your home directory and edit the copy. The following table explains where both files are searched. </p> <div class="table"> <a name="bbv2.reference.init.config"></a><p class="title"><b>Table 43.1. Search paths for configuration files</b></p> <div class="table-contents"><table class="table" summary="Search paths for configuration files"> <colgroup> <col> <col> <col> </colgroup> <thead><tr> <th> </th> <th>site-config.jam</th> <th>user-config.jam</th> </tr></thead> <tbody> <tr> <td>Linux</td> <td> <p><code class="computeroutput">/etc</code></p> <p><code class="computeroutput">$HOME</code></p> <p><code class="computeroutput">$BOOST_BUILD_PATH</code></p> </td> <td> <p><code class="computeroutput">$HOME</code></p> <p><code class="computeroutput">$BOOST_BUILD_PATH</code></p> </td> </tr> <tr> <td>Windows</td> <td> <p><code class="computeroutput">%SystemRoot%</code></p> <p><code class="computeroutput">%HOMEDRIVE%%HOMEPATH%</code></p> <p><code class="computeroutput">%HOME%</code></p> <p><code class="computeroutput">%BOOST_BUILD_PATH%</code></p> </td> <td> <p><code class="computeroutput">%HOMEDRIVE%%HOMEPATH%</code></p> <p><code class="computeroutput">%HOME%</code></p> <p><code class="computeroutput">%BOOST_BUILD_PATH%</code></p> </td> </tr> </tbody> </table></div> </div> <br class="table-break"><div class="tip"><table border="0" summary="Tip"> <tr> <td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="../../../doc/src/images/tip.png"></td> <th align="left">Tip</th> </tr> <tr><td align="left" valign="top"><p> You can use the <span class="command"><strong>--debug-configuration</strong></span> option to find which configuration files are actually loaded. </p></td></tr> </table></div> <p> Usually, <code class="filename">user-config.jam</code> just defines the available compilers and other tools (see <a class="xref" href="faq.html#bbv2.recipies.site-config" title="Targets in site-config.jam">the section called “Targets in site-config.jam”</a> for more advanced usage). A tool is configured using the following syntax: </p> <pre class="programlisting"> using <em class="replaceable"><code>tool-name</code></em> : ... ; </pre> <p> The <code class="computeroutput">using</code> rule is given the name of tool, and will make that tool available to Boost.Build. For example, </p> <pre class="programlisting"> using gcc ; </pre> <p> will make the <a href="http://gcc.gnu.org" target="_top">GCC</a> compiler available. </p> <p> All the supported tools are documented in <a class="xref" href="reference.html#bbv2.reference.tools" title="Builtin tools">the section called “Builtin tools”</a>, including the specific options they take. Some general notes that apply to most C++ compilers are below. </p> <p> For all the C++ compiler toolsets that Boost.Build supports out-of-the-box, the list of parameters to <code class="computeroutput">using</code> is the same: <em class="parameter"><code>toolset-name</code></em>, <em class="parameter"><code>version</code></em>, <em class="parameter"><code>invocation-command</code></em>, and <em class="parameter"><code>options</code></em>. </p> <p>If you have a single compiler, and the compiler executable </p> <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"><p>has its “usual name” and is in the <code class="envar">PATH</code>, or</p></li> <li class="listitem"><p>was installed in a standard “installation directory”, or</p></li> <li class="listitem"><p>can be found using a global system like the Windows registry.</p></li> </ul></div> <p> it can be configured by simply:</p> <pre class="programlisting"> using <em class="replaceable"><code>tool-name</code></em> ; </pre> <p>If the compiler is installed in a custom directory, you should provide the command that invokes the compiler, for example:</p> <pre class="programlisting"> using gcc : : g++-3.2 ; using msvc : : "Z:/Programs/Microsoft Visual Studio/vc98/bin/cl" ; </pre> <p> Some Boost.Build toolsets will use that path to take additional actions required before invoking the compiler, such as calling vendor-supplied scripts to set up its required environment variables. When the compiler executables for C and C++ are different, the path to the C++ compiler executable must be specified. The command can be any command allowed by the operating system. For example: </p> <pre class="programlisting"> using msvc : : echo Compiling && foo/bar/baz/cl ; </pre> <p> will work. </p> <p> To configure several versions of a toolset, simply invoke the <code class="computeroutput">using</code> rule multiple times: </p> <pre class="programlisting"> using gcc : 3.3 ; using gcc : 3.4 : g++-3.4 ; using gcc : 3.2 : g++-3.2 ; </pre> <p> Note that in the first call to <code class="computeroutput">using</code>, the compiler found in the <code class="envar">PATH</code> will be used, and there is no need to explicitly specify the command. </p> <p> Many of toolsets have an <em class="parameter"><code>options</code></em> parameter to fine-tune the configuration. All of Boost.Build's standard compiler toolsets accept four options <code class="varname">cflags</code>, <code class="varname">cxxflags</code>, <code class="varname">compileflags</code> and <code class="varname">linkflags</code> as <em class="parameter"><code>options</code></em> specifying flags that will be always passed to the corresponding tools. Values of the <code class="varname">cflags</code> feature are passed directly to the C compiler, values of the <code class="varname">cxxflags</code> feature are passed directly to the C++ compiler, and values of the <code class="varname">compileflags</code> feature are passed to both. For example, to configure a <span class="command"><strong>gcc</strong></span> toolset so that it always generates 64-bit code you could write: </p> <pre class="programlisting"> using gcc : 3.4 : : <compileflags>-m64 <linkflags>-m64 ; </pre> <p> </p> <div class="warning"><table border="0" summary="Warning"> <tr> <td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td> <th align="left">Warning</th> </tr> <tr><td align="left" valign="top"><p> Although the syntax used to specify toolset options is very similar to syntax used to specify requirements in Jamfiles, the toolset options are not the same as features. Don't try to specify a feature value in toolset initialization. </p></td></tr> </table></div> </div> <div class="section"> <div class="titlepage"><div><div><h3 class="title"> <a name="bbv2.overview.invocation"></a>Invocation</h3></div></div></div> <div class="toc"><dl class="toc"> <dt><span class="section"><a href="overview.html#bbv2.overview.invocation.examples">Examples</a></span></dt> <dt><span class="section"><a href="overview.html#bbv2.overview.invocation.options">Options</a></span></dt> <dt><span class="section"><a href="overview.html#bbv2.overview.invocation.properties">Properties</a></span></dt> <dt><span class="section"><a href="overview.html#bbv2.overview.invocation.targets">Targets</a></span></dt> </dl></div> <p>To invoke Boost.Build, type <span class="command"><strong>b2</strong></span> on the command line. Three kinds of command-line tokens are accepted, in any order:</p> <div class="variablelist"><dl class="variablelist"> <dt><span class="term">options</span></dt> <dd><p>Options start with either one or two dashes. The standard options are listed below, and each project may add additional options</p></dd> <dt><span class="term">properties</span></dt> <dd><p>Properties specify details of what you want to build (e.g. debug or release variant). Syntactically, all command line tokens with an equal sign in them are considered to specify properties. In the simplest form, a property looks like <span class="command"><strong><em class="replaceable"><code>feature</code></em>=<em class="replaceable"><code>value</code></em></strong></span> </p></dd> <dt><span class="term">target</span></dt> <dd><p>All tokens that are neither options nor properties specify what targets to build. The available targets entirely depend on the project you are building.</p></dd> </dl></div> <div class="section"> <div class="titlepage"><div><div><h4 class="title"> <a name="bbv2.overview.invocation.examples"></a>Examples</h4></div></div></div> <p>To build all targets defined in the Jamfile in the current directory with the default properties, run: </p> <pre class="screen"> b2 </pre> <p> </p> <p>To build specific targets, specify them on the command line: </p> <pre class="screen"> b2 lib1 subproject//lib2 </pre> <p> </p> <p>To request a certain value for some property, add <code class="literal"> <em class="replaceable"><code>property</code></em>=<em class="replaceable"><code>value</code></em></code> to the command line: </p> <pre class="screen"> b2 toolset=gcc variant=debug optimization=space </pre> <p> </p> </div> <div class="section"> <div class="titlepage"><div><div><h4 class="title"> <a name="bbv2.overview.invocation.options"></a>Options</h4></div></div></div> <p>Boost.Build recognizes the following command line options.</p> <div class="variablelist"><dl class="variablelist"> <dt> <a name="bbv2.reference.init.options.help"></a><span class="term"><code class="option">--help</code></span> </dt> <dd><p>Invokes the online help system. This prints general information on how to use the help system with additional --help* options. </p></dd> <dt><span class="term"><code class="option">--clean</code></span></dt> <dd><p>Cleans all targets in the current directory and in any subprojects. Note that unlike the <code class="literal">clean</code> target in make, you can use <code class="literal">--clean</code> together with target names to clean specific targets.</p></dd> <dt><span class="term"><code class="option">--clean-all</code></span></dt> <dd><p>Cleans all targets, no matter where they are defined. In particular, it will clean targets in parent Jamfiles, and targets defined under other project roots. </p></dd> <dt><span class="term"><code class="option">--build-dir</code></span></dt> <dd> <p>Changes the build directories for all project roots being built. When this option is specified, all Jamroot files must declare a project name. The build directory for the project root will be computed by concatanating the value of the <code class="option">--build-dir</code> option, the project name specified in Jamroot, and the build dir specified in Jamroot (or <code class="literal">bin</code>, if none is specified). </p> <p>The option is primarily useful when building from read-only media, when you can't modify Jamroot. </p> </dd> <dt><span class="term"><code class="option">--abbreviate-paths</code></span></dt> <dd><p>Compresses target paths by abbreviating each component. This option is useful to keep paths from becoming longer than the filesystem supports. See also <a class="xref" href="reference.html#bbv2.reference.buildprocess.targetpath" title="Target Paths">the section called “Target Paths”</a>. </p></dd> <dt><span class="term"><code class="option">--hash</code></span></dt> <dd><p>Compresses target paths using an MD5 hash. This option is useful to keep paths from becoming longer than the filesystem supports. This option produces shorter paths than --abbreviate-paths does, but at the cost of making them less understandable. See also <a class="xref" href="reference.html#bbv2.reference.buildprocess.targetpath" title="Target Paths">the section called “Target Paths”</a>. </p></dd> <dt><span class="term"><code class="option">--version</code></span></dt> <dd><p>Prints information on the Boost.Build and Boost.Jam versions. </p></dd> <dt><span class="term"><code class="option">-a</code></span></dt> <dd><p>Causes all files to be rebuilt.</p></dd> <dt><span class="term"><code class="option">-n</code></span></dt> <dd><p>Do no execute the commands, only print them.</p></dd> <dt><span class="term"><code class="option">-q</code></span></dt> <dd><p>Stop at the first error, as opposed to continuing to build targets that don't depend on the failed ones.</p></dd> <dt><span class="term"><code class="option">-j <em class="replaceable"><code>N</code></em></code></span></dt> <dd><p>Run up to <em class="replaceable"><code>N</code></em> commands in parallel.</p></dd> <dt><span class="term"><code class="option">--debug-configuration</code></span></dt> <dd><p>Produces debug information about the loading of Boost.Build and toolset files.</p></dd> <dt><span class="term"><code class="option">--debug-building</code></span></dt> <dd><p>Prints what targets are being built and with what properties. </p></dd> <dt><span class="term"><code class="option">--debug-generators</code></span></dt> <dd><p>Produces debug output from the generator search process. Useful for debugging custom generators. </p></dd> <dt><span class="term"><code class="option">-d0</code></span></dt> <dd><p>Supress all informational messages.</p></dd> <dt><span class="term"><code class="option">-d <em class="replaceable"><code>N</code></em></code></span></dt> <dd> <p>Enable cummulative debugging levels from 1 to n. Values are: </p> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem">Show the actions taken for building targets, as they are executed (the default).</li> <li class="listitem">Show "quiet" actions and display all action text, as they are executed.</li> <li class="listitem">Show dependency analysis, and target/source timestamps/paths.</li> <li class="listitem">Show arguments and timming of shell invocations.</li> <li class="listitem">Show rule invocations and variable expansions.</li> <li class="listitem">Show directory/header file/archive scans, and attempts at binding to targets.</li> <li class="listitem">Show variable settings.</li> <li class="listitem">Show variable fetches, variable expansions, and evaluation of '"if"' expressions.</li> <li class="listitem">Show variable manipulation, scanner tokens, and memory usage.</li> <li class="listitem">Show profile information for rules, both timing and memory.</li> <li class="listitem">Show parsing progress of Jamfiles.</li> <li class="listitem">Show graph of target dependencies.</li> <li class="listitem">Show change target status (fate).</li> </ol></div> <p> </p> </dd> <dt><span class="term"><code class="option">-d +<em class="replaceable"><code>N</code></em></code></span></dt> <dd><p>Enable debugging level <em class="replaceable"><code>N</code></em>.</p></dd> <dt><span class="term"><code class="option">-o <em class="replaceable"><code>file</code></em></code></span></dt> <dd><p>Write the updating actions to the specified file instead of running them. </p></dd> <dt><span class="term"><code class="option">-s <em class="replaceable"><code>var</code></em>=<em class="replaceable"><code>value</code></em></code></span></dt> <dd><p>Set the variable <em class="replaceable"><code>var</code></em> to <em class="replaceable"><code>value</code></em> in the global scope of the jam language interpreter, overriding variables imported from the environment. </p></dd> </dl></div> </div> <div class="section"> <div class="titlepage"><div><div><h4 class="title"> <a name="bbv2.overview.invocation.properties"></a>Properties</h4></div></div></div> <p>In the simplest case, the build is performed with a single set of properties, that you specify on the command line with elements in the form <span class="command"><strong><em class="replaceable"><code>feature</code></em>=<em class="replaceable"><code>value</code></em></strong></span>. The complete list of features can be found in <a class="xref" href="reference.html#bbv2.overview.builtins.features" title="Builtin features">the section called “Builtin features”</a>. The most common features are summarized below.</p> <div class="table"> <a name="idp547594672"></a><p class="title"><b>Table 43.2. </b></p> <div class="table-contents"><table class="table"> <colgroup> <col> <col> <col> </colgroup> <thead><tr> <th>Feature</th> <th>Allowed values</th> <th>Notes</th> </tr></thead> <tbody> <tr> <td>variant</td> <td>debug,release</td> <td> </td> </tr> <tr> <td>link</td> <td>shared,static</td> <td>Determines if Boost.Build creates shared or static libraries</td> </tr> <tr> <td>threading</td> <td>single,multi</td> <td>Cause the produced binaries to be thread-safe. This requires proper support in the source code itself.</td> </tr> <tr> <td>address-model</td> <td>32,64</td> <td>Explicitly request either 32-bit or 64-bit code generation. This typically requires that your compiler is appropriately configured. Please refer to <a class="xref" href="reference.html#bbv2.reference.tools.compilers" title="C++ Compilers">the section called “C++ Compilers”</a> and your compiler documentation in case of problems.</td> </tr> <tr> <td>toolset</td> <td>(Depends on configuration)</td> <td>The C++ compiler to use. See <a class="xref" href="reference.html#bbv2.reference.tools.compilers" title="C++ Compilers">the section called “C++ Compilers”</a> for a detailed list.</td> </tr> <tr> <td>include</td> <td>(Arbitrary string)</td> <td>Additional include paths for C and C++ compilers.</td> </tr> <tr> <td>define</td> <td>(Arbitrary string)</td> <td>Additional macro definitions for C and C++ compilers. The string should be either <code class="computeroutput">SYMBOL</code> or <code class="computeroutput">SYMBOL=VALUE</code> </td> </tr> <tr> <td>cxxflags</td> <td>(Arbitrary string)</td> <td>Custom options to pass to the C++ compiler.</td> </tr> <tr> <td>cflags</td> <td>(Arbitrary string)</td> <td>Custom options to pass to the C compiler.</td> </tr> <tr> <td>linkflags</td> <td>(Arbitrary string)</td> <td>Custom options to pass to the C++ linker.</td> </tr> <tr> <td>runtime-link</td> <td>shared,static</td> <td>Determines if shared or static version of C and C++ runtimes should be used.</td> </tr> </tbody> </table></div> </div> <br class="table-break"><p>If you have more than one version of a given C++ toolset (e.g. configured in <code class="filename">user-config.jam</code>, or autodetected, as happens with msvc), you can request the specific version by passing <code class="computeroutput"><em class="replaceable"><code>toolset</code></em>-<em class="replaceable"><code>version</code></em></code> as the value of the <code class="computeroutput">toolset</code> feature, for example <code class="computeroutput">toolset=msvc-8.0</code>. </p> <p> If a feature has a fixed set of values it can be specified more than once on the command line. In which case, everything will be built several times -- once for each specified value of a feature. For example, if you use </p> <pre class="screen"> b2 link=static link=shared threading=single threading=multi </pre> <p> Then a total of 4 builds will be performed. For convenience, instead of specifying all requested values of a feature in separate command line elements, you can separate the values with commas, for example: </p> <pre class="screen"> b2 link=static,shared threading=single,multi </pre> <p> The comma has this special meaning only if the feature has a fixed set of values, so </p> <pre class="screen"> b2 include=static,shared </pre> <p>is not treated specially.</p> </div> <div class="section"> <div class="titlepage"><div><div><h4 class="title"> <a name="bbv2.overview.invocation.targets"></a>Targets</h4></div></div></div> <p>All command line elements that are neither options nor properties are the names of the targets to build. See <a class="xref" href="reference.html#bbv2.reference.ids" title="Target identifiers and references">the section called “Target identifiers and references”</a>. If no target is specified, the project in the current directory is built.</p> </div> </div> <div class="section"> <div class="titlepage"><div><div><h3 class="title"> <a name="bbv2.overview.targets"></a>Declaring Targets</h3></div></div></div> <div class="toc"><dl class="toc"> <dt><span class="section"><a href="overview.html#idp547651648">Name</a></span></dt> <dt><span class="section"><a href="overview.html#idp547657376">Sources</a></span></dt> <dt><span class="section"><a href="overview.html#bbv2.overview.targets.requirements">Requirements</a></span></dt> <dt><span class="section"><a href="overview.html#idp547693696">Default Build</a></span></dt> <dt><span class="section"><a href="overview.html#idp547696512">Additional Information</a></span></dt> </dl></div> <p><a name="bbv2.overview.targets.main"></a> A <em class="firstterm">Main target</em> is a user-defined named entity that can be built, for example an executable file. Declaring a main target is usually done using one of the main target rules described in <a class="xref" href="reference.html#bbv2.reference.rules" title="Builtin rules">the section called “Builtin rules”</a>. The user can also declare custom main target rules as shown in <a class="xref" href="extender.html#bbv2.extending.rules" title="Main target rules">the section called “Main target rules”</a>. </p> <a class="indexterm" name="idp547635040"></a><p>Most main target rules in Boost.Build have the same common signature:</p> <a class="indexterm" name="idp547636688"></a><a name="bbv2.main-target-rule-syntax"></a><pre class="programlisting"> rule <em class="replaceable"><code>rule-name</code></em> ( main-target-name : sources + : requirements * : default-build * : usage-requirements * ) </pre> <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <em class="parameter"><code>main-target-name</code></em> is the name used to request the target on command line and to use it from other main targets. A main target name may contain alphanumeric characters, dashes (‘<code class="computeroutput">-</code>’), and underscores (‘<code class="computeroutput">_</code>’). </li> <li class="listitem"> <em class="parameter"><code>sources</code></em> is the list of source files and other main targets that must be combined. </li> <li class="listitem"> <em class="parameter"><code>requirements</code></em> is the list of properties that must always be present when this main target is built. </li> <li class="listitem"> <em class="parameter"><code>default-build</code></em> is the list of properties that will be used unless some other value of the same feature is already specified, e.g. on the command line or by propagation from a dependent target. </li> <li class="listitem"> <em class="parameter"><code>usage-requirements</code></em> is the list of properties that will be propagated to all main targets that use this one, i.e. to all its dependents. </li> </ul></div> <p> Some main target rules have a different list of parameters as explicitly stated in their documentation. </p> <p>The actual requirements for a target are obtained by refining the requirements of the project where the target is declared with the explicitly specified requirements. The same is true for usage-requirements. More details can be found in <a class="xref" href="reference.html#bbv2.reference.variants.proprefine" title="Property refinement">the section called “Property refinement”</a> </p> <div class="section"> <div class="titlepage"><div><div><h4 class="title"> <a name="idp547651648"></a>Name</h4></div></div></div> <p>The name of main target has two purposes. First, it's used to refer to this target from other targets and from command line. Second, it's used to compute the names of the generated files. Typically, filenames are obtained from main target name by appending system-dependent suffixes and prefixes. </p> <p>The name of a main target can contain alphanumeric characters, dashes, undescores and dots. The entire name is significant when resolving references from other targets. For determining filenames, only the part before the first dot is taken. For example:</p> <pre class="programlisting"> obj test.release : test.cpp : <variant>release ; obj test.debug : test.cpp : <variant>debug ; </pre> <p>will generate two files named <code class="filename">test.obj</code> (in two different directories), not two files named <code class="filename">test.release.obj</code> and <code class="filename">test.debug.obj</code>. </p> </div> <div class="section"> <div class="titlepage"><div><div><h4 class="title"> <a name="idp547657376"></a>Sources</h4></div></div></div> <p>The list of sources specifies what should be processed to get the resulting targets. Most of the time, it's just a list of files. Sometimes, you'll want to automatically construct the list of source files rather than having to spell it out manually, in which case you can use the <a class="link" href="reference.html#bbv2.reference.rules.glob">glob</a> rule. Here are two examples:</p> <pre class="programlisting"> exe a : a.cpp ; # a.cpp is the only source file exe b : [ glob *.cpp ] ; # all .cpp files in this directory are sources </pre> <p> Unless you specify a file with an absolute path, the name is considered relative to the source directory — which is typically the directory where the Jamfile is located, but can be changed as described in <a class="xref" href="overview.html#bbv2.overview.projects.attributes.projectrule">the section called “Projects”</a>. </p> <p> The list of sources can also refer to other main targets. Targets in the same project can be referred to by name, while targets in other projects must be qualified with a directory or a symbolic project name. The directory/project name is separated from the target name by a double forward slash. There is no special syntax to distinguish the directory name from the project name—the part before the double slash is first looked up as project name, and then as directory name. For example: </p> <pre class="programlisting"> lib helper : helper.cpp ; exe a : a.cpp helper ; # Since all project ids start with slash, ".." is a directory name. exe b : b.cpp ..//utils ; exe c : c.cpp /boost/program_options//program_options ; </pre> <p> The first exe uses the library defined in the same project. The second one uses some target (most likely a library) defined by a Jamfile one level higher. Finally, the third target uses a <a href="http://boost.org" target="_top">C++ Boost</a> library, referring to it using its absolute symbolic name. More information about target references can be found in <a class="xref" href="tutorial.html#bbv2.tutorial.libs" title="Dependent Targets">the section called “Dependent Targets”</a> and <a class="xref" href="reference.html#bbv2.reference.ids" title="Target identifiers and references">the section called “Target identifiers and references”</a>. </p> </div> <div class="section"> <div class="titlepage"><div><div><h4 class="title"> <a name="bbv2.overview.targets.requirements"></a>Requirements</h4></div></div></div> <a class="indexterm" name="idp547669088"></a><p>Requirements are the properties that should always be present when building a target. Typically, they are includes and defines: </p> <pre class="programlisting"> exe hello : hello.cpp : <include>/opt/boost <define>MY_DEBUG ; </pre> <p> There are a number of other features, listed in <a class="xref" href="reference.html#bbv2.overview.builtins.features" title="Builtin features">the section called “Builtin features”</a>. For example if a library can only be built statically, or a file can't be compiled with optimization due to a compiler bug, one can use </p> <pre class="programlisting"> lib util : util.cpp