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Add %proxycode directive for adding code into proxy classes for C#, D and Java

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William S Fulton 2017-01-13 20:42:12 +00:00
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Doc/Manual/Java.html
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@ -100,6 +100,7 @@
<ul>
<li><a href="#Java_helper_functions">C/C++ helper functions</a>
<li><a href="#Java_class_extension">Class extension with %extend</a>
<li><a href="#Java_proxycode">Class extension with %proxycode</a>
<li><a href="#Java_exception_handling">Exception handling with %exception and %javaexception</a>
<li><a href="#Java_method_access">Method access with %javamethodmodifiers</a>
</ul>
@ -4363,7 +4364,144 @@ Vector(2, 3, 4)
in any way---the extensions only show up in the Java interface.
</p>
<H3><a name="Java_exception_handling">25.7.3 Exception handling with %exception and %javaexception</a></H3>
<H3><a name="Java_proxycode">25.7.3 Class extension with %proxycode</a></H3>
<p>
The previous section described how to extend a wrapped class with C or C++ code.
This section describes how to extend a wrapped class with Java code instead of C/C++ code.
The <tt>%proxycode</tt> directive is used and is just a macro for <tt>%insert("proxycode")</tt>.
The <a href="SWIG.html#SWIG_nn42">Code insertion block</a> section describes the <tt>%insert</tt> directive.
The section of code for insertion is "proxycode", that is, the Java proxy class.
This directive must hence only be used within the scope of a class, otherwise it is silently ignored.
There are two common ways to get the scope correct.
</p>
<p>
The first is to use <tt>%proxycode</tt> inside a class that SWIG parses, for example a <tt>toString()</tt> method can be added to a C++ class using pure Java code.
A C++ header file can mix C++ and Java code inside the C++ class as follows:
</p>
<div class="code">
<pre>
// flag.h header file
class Flag {
bool flag;
public:
Flag(bool flag) : flag(flag) {}
bool FetchFlag() { return flag; }
#if defined(SWIG)
%proxycode %{
public String toString() {
boolean flag = FetchFlag();
return Boolean.toString(flag);
}
%}
#endif
};
</pre>
</div>
<p>
and wrapped using:
</p>
<div class="code">
<pre>
%{
#include "flag.h"
%}
%include "flag.h"
</pre>
</div>
<p>
The second is to use <tt>%proxycode</tt> within <tt>%extend</tt> as everything within a <tt>%extend</tt> block is effectively within the scope of the class, for example:
</p>
<div class="code">
<pre>
// flag.h header file
class Flag {
bool flag;
public:
Flag(bool flag) : flag(flag) {}
bool FetchFlag() { return flag; }
};
</pre>
</div>
<p>
and wrapped using:
</p>
<div class="code">
<pre>
%{
#include "flag.h"
%}
%include "flag.h"
%extend Flag {
#if defined(SWIG)
%proxycode %{
public String toString() {
boolean flag = FetchFlag();
return Boolean.toString(flag);
}
%}
#endif
}
</pre>
</div>
<p>
There is some very limited support of typemaps within a <tt>%proxycode</tt> block.
A useful trick is to obtain the Java type for a given C/C++ type using the <a href="Typemaps.html#Typemaps_special_macro_typemap">$typemap</a> special macro.
The following C++ template demonstrates this:
</p>
<div class="code">
<pre>
%inline %{
template&lt;typename T&gt; struct Value {
T value;
Value(const T&amp; val) : value(val) {}
};
%}
%extend Value {
%proxycode %{
public String toString() {
// Note template type expansion is supported, so T is expanded to 'unsigned int' in this example
// and $typemap(jstype, unsigned int) in turn is expanded to 'long'
$typemap(jstype, T) val = getValue();
return "$javaclassname value: " + val + " Java type: $typemap(jstype, T) JNI type: $typemap(jni, T)";
}
%}
}
%template(ValueUnsignedInt) Value&lt;unsigned int&gt;;
</pre>
</div>
<p>
The generated Java contains the expanded special variable and macro resulting in Java proxy code:
</p>
<div class="code">
<pre>
public class ValueUnsignedInt {
...
public String toString() {
long val = getValue();
return "ValueUnsignedInt value: " + val + " Java type: long JNI type: jlong";
}
}
</pre>
</div>
<H3><a name="Java_exception_handling">25.7.4 Exception handling with %exception and %javaexception</a></H3>
<p>
@ -4522,7 +4660,7 @@ to raise exceptions. See the <a href="Library.html#Library">SWIG Library</a> ch
The typemap example <a href="#Java_exception_typemap">Handling C++ exception specifications as Java exceptions</a> provides further exception handling capabilities.
</p>
<H3><a name="Java_method_access">25.7.4 Method access with %javamethodmodifiers</a></H3>
<H3><a name="Java_method_access">25.7.5 Method access with %javamethodmodifiers</a></H3>
<p>