examples: add a cgo-based package

Change-Id: I602af8071eff4f38bdea1817acbcba98de2720c1

_examples/cpkg/cpkg.go

@@ -0,0 +1,28 @@
+// Copyright 2015 The go-python Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpkg
+
+//#include <stdio.h>
+//#include <string.h>
+//#include <stdlib.h>
+//void hello(const char *str) {
+//	fprintf(stdout, str);
+//}
+import "C"
+
+import (
+	"fmt"
+	"unsafe"
+)
+
+// Hello prints a string via C's stdio
+func Hello(s string) {
+	if s == "" {
+		s = "you"
+	}
+	cstr := C.CString(fmt.Sprintf("hello %s from C\n", s))
+	defer C.free(unsafe.Pointer(cstr))
+	C.hello(cstr)
+}

_examples/cpkg/run.go

@@ -0,0 +1,21 @@
+// Copyright 2015 The go-python Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package main
+
+import (
+	"fmt"
+
+	"github.com/go-python/gopy/_examples/cpkg"
+)
+
+func main() {
+	fmt.Printf("hello from go\n")
+	cpkg.Hello("me")
+	fmt.Printf("bye me\n")
+	cpkg.Hello("you")
+	fmt.Printf("bye you\n")
+}