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[Go] Revert commit 5e88857 to undelete the 'callback' and 'extend' examples.

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The 'callback' and 'extend' examples were presumed to be obsoleted by the new
'director' example.  The examples are helpful though to have similar examples
across target languages and hence the commit @5e88857 which removed these
examples got reverted.
This commit is contained in:
Michael Schaller 2015-08-08 19:44:41 +02:00
commit a941e5b605
14 changed files with 374 additions and 1 deletions
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16
Examples/go/callback/Makefile Normal file
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TOP = ../..
SWIG = $(TOP)/../preinst-swig
CXXSRCS = callback.cxx
TARGET = example
INTERFACE = example.i
SWIGOPT =
check: build
$(MAKE) -f $(TOP)/Makefile SRCDIR='$(SRCDIR)' CXXSRCS='$(CXXSRCS)' TARGET='$(TARGET)' INTERFACE='$(INTERFACE)' go_run
build:
$(MAKE) -f $(TOP)/Makefile SRCDIR='$(SRCDIR)' CXXSRCS='$(CXXSRCS)' SWIG='$(SWIG)' \
SWIGOPT='$(SWIGOPT)' TARGET='$(TARGET)' INTERFACE='$(INTERFACE)' go_cpp
clean:
$(MAKE) -f $(TOP)/Makefile SRCDIR='$(SRCDIR)' INTERFACE='$(INTERFACE)' go_clean

4
Examples/go/callback/callback.cxx Normal file
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/* File : example.cxx */
#include "example.h"

23
Examples/go/callback/example.h Normal file
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/* File : example.h */
#include <cstdio>
#include <iostream>
class Callback {
public:
virtual ~Callback() { std::cout << "Callback::~Callback()" << std:: endl; }
virtual void run() { std::cout << "Callback::run()" << std::endl; }
};
class Caller {
private:
Callback *_callback;
public:
Caller(): _callback(0) {}
~Caller() { delCallback(); }
void delCallback() { delete _callback; _callback = 0; }
void setCallback(Callback *cb) { delCallback(); _callback = cb; }
void call() { if (_callback) _callback->run(); }
};

11
Examples/go/callback/example.i Normal file
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/* File : example.i */
%module(directors="1") example
%{
#include "example.h"
%}
/* turn on director wrapping Callback */
%feature("director") Callback;
%include "example.h"

81
Examples/go/callback/index.html Normal file
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<html>
<head>
<title>SWIG:Examples:go:callback</title>
</head>
<body bgcolor="#ffffff">
<tt>SWIG/Examples/go/callback/</tt>
<hr>
<H2>Implementing C++ callbacks in Go</H2>
<p>
This example illustrates how to use directors to implement C++
callbacks in Go.
</p>
<p>
Because Go and C++ use inheritance differently, you must call a
different function to create a class which uses callbacks. Instead of
calling the usual constructor function whose name is <tt>New</tt>
followed by the capitalized name of the class, you call a function
named <tt>NewDirector</tt> followed by the capitalized name of the
class.
</p>
<p>
The first argument to the <tt>NewDirector</tt> function is an instance
of a type. The <tt>NewDirector</tt> function will return an interface
value as usual. However, when calling any method on the returned
value, the program will first check whether the value passed
to <tt>NewDirector</tt> implements that method. If it does, the
method will be called in Go. This is true whether the method is
called from Go code or C++ code.
</p>
<p>
Note that the Go code will be called with just the Go value, not the
C++ value. If the Go code needs to call a C++ method on itself, you
need to get a copy of the C++ object. This is typically done as
follows:
<blockquote>
<pre>
type Child struct { abi Parent }
func (p *Child) ChildMethod() {
p.abi.ParentMethod()
}
func f() {
p := &Child{nil}
d := NewDirectorParent(p)
p.abi = d
...
}
</pre>
</blockquote>
In other words, we first create the Go value. We pass that to
the <tt>NewDirector</tt> function to create the C++ value; this C++
value will be created with an association to the Go value. We then
store the C++ value in the Go value, giving us the reverse
association. That permits us to call parent methods from the child.
</p>
<p>
To delete a director object, use the function <tt>DeleteDirector</tt>
followed by the capitalized name of the class.
</p>
<p>
<ul>
<li><a href="example.h">example.h</a>. Header file containing some enums.
<li><a href="example.i">example.i</a>. Interface file.
<li><a href="runme.go">runme.go</a>. Sample Go program.
</ul>
<hr>
</body>
</html>

41
Examples/go/callback/runme.go Normal file
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package main
import (
. "./example"
"fmt"
)
func main() {
fmt.Println("Adding and calling a normal C++ callback")
fmt.Println("----------------------------------------")
caller := NewCaller()
callback := NewCallback()
caller.SetCallback(callback)
caller.Call()
caller.DelCallback()
callback = NewDirectorCallback(new(GoCallback))
fmt.Println()
fmt.Println("Adding and calling a Go callback")
fmt.Println("------------------------------------")
caller.SetCallback(callback)
caller.Call()
caller.DelCallback()
// Test that a double delete does not occur as the object has
// already been deleted from the C++ layer.
DeleteDirectorCallback(callback)
fmt.Println()
fmt.Println("Go exit")
}
type GoCallback struct{}
func (p *GoCallback) Run() {
fmt.Println("GoCallback.Run")
}