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From: oryol_at_[hidden]
Date: 2008-02-09 23:22:33

Author: jeremypack
Date: 2008-02-09 23:22:32 EST (Sat, 09 Feb 2008)
New Revision: 43203
URL: http://svn.boost.org/trac/boost/changeset/43203

Log:
extension/reflection example

Added:
sandbox/libs/reflection/doc/html/boost_reflection/extension.html (contents, props changed)

Added: sandbox/libs/reflection/doc/html/boost_reflection/extension.html
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+<html>
+<head>
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+<title> Boost.Extension Interoperability</title>
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+<div class="section" lang="en">
+<div class="titlepage"><div><div><h2 class="title" style="clear: both">
+<a name="boost_reflection.extension"></a> Boost.Extension Interoperability</h2></div></div></div>
+
+ Reflections are designed to work with Boost.Extension, or with shared libraries
+ in general. A simple example is included in examplesextension.
+ 
+
+ Declaring the reflected class itself is similar to the process for doing the
+ same in Boost.Extension.
+ 
+
+ Here's how the Jamfile for these libraries is defined. Note that, like in Boost.Extension,
+ one can rename the shared library extensions, for consistency across platforms.
+ Here, we use the .reflection suffix for each shared library.
+
+<pre class="programlisting">
+import type : change-generated-target-suffix ;
+import type : change-generated-target-prefix ;
+type.change-generated-target-suffix SHARED_LIB : : reflection ;
+type.change-generated-target-prefix SHARED_LIB : : lib ;
+exe extension-reflection : extension/extension.cpp ;
+lib car_lib : extension/car_lib.cpp : <link>shared ;
+</pre>
+
+ 
+
+ The code in the shared library is defined in car_lib.cpp.
+ 
+
+ We define two classes to export as reflections. Although both of these classes
+ are derived from a common base, this is certainly not necessary. If we were
+ using Boost.Extension factories, this would be required.
+
+<pre class="programlisting">
+class suv : public car
+{
+public:
+ suv(const char * name) : car(name) {}
+ virtual const char * get_type(void) { return "It's an SUV."; }
+ virtual ~suv(void) {}
+};
+
+class compact : public car
+{
+public:
+ compact(const char * name) : car(name) {}
+ virtual const char * get_type(void) { return "It's a compact."; }
+ virtual ~compact(void) {}
+};
+</pre>
+
+ 
+
+ Just like Boost.Extension, an external function needs to be defined that will
+ be called by the main module.
+ 
+
+ extern "C" void BOOST_EXTENSION_EXPORT_DECL extension_export_car(std::map<std::string,
+ reflection> reflection_map) { reflection & first = reflection_map“suv"”;
+ reflection & second = reflection_map“compact"”;
+ 
+<pre class="programlisting">
+// Create a reflector for each type that is being reflected.
+reflector<suv> suv_reflector(&first);
+reflector<compact> compact_reflector(&second);
+
+// Reflect the constructor with a `const char*` arg
+suv_reflector.reflect_constructor<const char *>();
+compact_reflector.reflect_constructor<const char *>();
+
+// Reflect a function for each
+suv_reflector.reflect<const char *>(&suv::get_type, "get_type");
+compact_reflector.reflect<const char *>(&compact::get_type, "get_type");
+</pre>
+
+ // Create a reflector for each type that is being reflected. reflector<suv>
+ suv_reflector(&first); reflector<compact> compact_reflector(&second);
+ 
+<pre class="programlisting">
+// Reflect the constructor with a `const char*` arg
+suv_reflector.reflect_constructor<const char *>();
+compact_reflector.reflect_constructor<const char *>();
+
+// Reflect a function for each
+suv_reflector.reflect<const char *>(&suv::get_type, "get_type");
+compact_reflector.reflect<const char *>(&compact::get_type, "get_type");
+</pre>
+
+ // Reflect the constructor with a <code class="computeroutput">const char*</code> arg suv_reflector.reflect_constructor<const
+ char *>(); compact_reflector.reflect_constructor<const char *>();
+ 
+<pre class="programlisting">
+// Reflect a function for each
+suv_reflector.reflect<const char *>(&suv::get_type, "get_type");
+compact_reflector.reflect<const char *>(&compact::get_type, "get_type");
+</pre>
+
+ // Reflect a function for each suv_reflector.reflect<const char *>(&suv::get_type,
+ "get_type"); compact_reflector.reflect<const char *>(&compact::get_type,
+ "get_type"); }
+ 
+
+ This is all that is necessary to export one constructor and one function for
+ each class.
+ 
+
+ Now, in extension.cpp, we combine Boost.Extension and Boost.Reflection code
+ to load and use the reflections declared in the shared library.
+ 
+
+ Create a mapping of reflections to strings that will be populated inside the
+ shared library.
+
+<pre class="programlisting">
+std::map<std::string, reflection> reflection_map;
+</pre>
+
+ Load the shared library using Boost.Extension.
+
+<pre class="programlisting">
+boost::extensions::shared_library lib
+ ((std::string(BOOST_EXTENSION_DIR_START) +
+ "libcar_lib.extension").c_str());
+lib.open();
+</pre>
+
+ Call an exported function to populate reflection_map.
+
+<pre class="programlisting">
+lib.get<void, std::map<std::string,
+ reflection> &>
+ ("extension_export_car")(reflection_map);
+if (reflection_map.size() != size_t(2)) {
+ std::cout << "Could not load reflections!";
+ return 1;
+}
+</pre>
+
+ Pull out two reflections that were named "suv" and "compact"
+ respectively.
+
+<pre class="programlisting">
+reflection & first_reflection =
+ reflection_map["suv"];
+reflection & second_reflection =
+ reflection_map["compact"];
+</pre>
+
+ Use the get_constructor function to find a constructor that takes one argument,
+ a const char*.
+
+<pre class="programlisting">
+instance_constructor<const char *> first_constructor =
+ first_reflection.get_constructor<const char *>();
+</pre>
+
+ Use the constructor retrieved to create an instance. Warning! instances should
+ only be used with functions and constructors generated by a single reflection
+ object.
+
+<pre class="programlisting">
+instance first_instance =
+ first_constructor("First Instance");
+</pre>
+
+ Get a function to call on this instance.
+
+<pre class="programlisting">
+boost::reflections::function<const char *> first_function =
+ first_reflection.get_function<const char *>("get_type");
+std::cout << "First reflection: " << first_function(first_instance)
+ << std::endl;
+ </pre>
+
+ Repeat the steps for the second reflection.
+
+<pre class="programlisting">
+instance_constructor<const char *> second_constructor =
+ second_reflection.get_constructor<const char *>();
+instance second_instance =
+ second_constructor("Second Instance");
+boost::reflections::function<const char *> second_function =
+ second_reflection.get_function<const char *>("get_type");
+std::cout << "Second reflection: " << second_function(second_instance)
+ << std::endl;
+</pre>
+
+ 
+</div>
+<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
+<td align="left"></td>
+<td align="right"><div class="copyright-footer">Copyright © 2007 -2008 Jeremy Pack, Mariano G. Consoni
+ Distributed under the Boost Software License, Version 1.0. (See accompanying
+ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ 
+</div></td>
+</tr></table>
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