Simple demonstration of generating swig bindings for a C++ class for guile

Author: jarod

.gitignore

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+*.so
+*.o

example.cpp

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+#include "example.h"
+
+MyClass::MyClass(int initialValue) : value(initialValue) {}
+
+int MyClass::getValue() const {
+    return value;
+}
+
+void MyClass::setValue(int newValue) {
+    value = newValue;
+}
+
+extern "C" {
+    MyClass* create_object(int initialValue) {
+        return new MyClass(initialValue);
+    }
+
+    int get_value(MyClass* obj) {
+        return obj->getValue();
+    }
+
+    void set_value(MyClass* obj, int newValue) {
+        obj->setValue(newValue);
+    }
+
+    void delete_object(MyClass* obj) {
+        delete obj;
+    }
+}

example.h

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+// example.hpp
+class MyClass {
+public:
+    MyClass(int initialValue);
+    int getValue() const;
+    void setValue(int newValue);
+private:
+    int value;
+};

example.i

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+%module example
+%{
+#include "example.h"
+%}
+
+%include "example.h"

example.scm

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+; example.scm
+;(use-modules (system foreign) (system foreign-library) (ice-9 ftw))
+
+;(define libexample (dynamic-link "./libexample.so"))
+
+;(define create-object (foreign-library-function libexample "create_object"
+;  #:return-type intptr_t
+;  #:arg-types int))
+;(define get-value (foreign-library-function libexample "get_value"
+;  #:return-type int
+;  #:arg-types intptr_t))
+;(define set-value (foreign-library-function libexample "set_value"
+;  #:return-type void
+;  #:arg-types (intptr_t int))
+;(define delete-object (foreign-library-function libexample "delete_object"
+;  #:return-type void
+;  #:arg-types intptr_t))
+
+;(define create-object (foreign-library-function libexample "create_object"))
+;(define get-value (foreign-library-function  libexample "get_value"))
+;(define set-value (foreign-library-function libexample "set_value"))
+;(define delete-object (foreign-library-function libexample "delete_object"))
+
+;(define (cleanup)
+;  (dynamic-unlink libexample))
+(load-extension "./libexample.so" "SWIG_init")
+
+; Example of using the C++ code from Scheme
+(display "Creating C++ object from Scheme: ")
+(let* ((obj (new-MyClass 42))
+       (initial-value (MyClass-getValue obj)))
+  (display "Initial value: ")
+  (display initial-value)
+  (newline)
+
+  (display "Setting new value from Scheme: ")
+  (MyClass-setValue obj 99)
+  (display "New value: ")
+  (display (MyClass-getValue obj))
+  (newline)
+
+  (delete-MyClass obj)) ; Clean up the C++ object
+
+; Cleanup - close the shared library
+;(cleanup)

instructions.txt

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+swig -c++ -guile example.i
+
+g++ -fPIC -I/usr/include/guile/3.0 -c example_wrap.cxx
+g++ -fPIC -c example.cpp
+g++ -shared example.o example_wrap.o -o libexample.so