diff -r 000000000000 -r 6474c204b198 xpcom/sample/nsSample.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/sample/nsSample.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,103 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSample_h
+#define nsSample_h
+
+/**
+ * A sample of XPConnect. This file is the header of an implementation
+ * nsSample of the nsISample interface.
+ *
+ */
+
+#include "nsISample.h"
+#include "mozilla/Attributes.h"
+
+/**
+ * SampleImpl is an implementation of the nsISample interface.  In XPCOM,
+ * there can be more than one implementation of an given interface.  Class
+ * IDs (CIDs) uniquely identify a particular implementation of an interface.
+ * Interface IDs (IIDs) uniquely identify an interface.
+ *
+ * The CID is also a unique number that looks just like an IID
+ * and uniquely identifies an implementation
+ * {7CB5B7A0-07D7-11d3-BDE2-000064657374}
+ */
+
+#define NS_SAMPLE_CID \
+{ 0x7cb5b7a0, 0x7d7, 0x11d3, { 0xbd, 0xe2, 0x0, 0x0, 0x64, 0x65, 0x73, 0x74 } }
+
+#define NS_SAMPLE_CONTRACTID "@mozilla.org/sample;1"
+
+
+class nsSampleImpl MOZ_FINAL : public nsISample
+{
+public:
+    nsSampleImpl();
+
+    /**
+     * This macro expands into a declaration of the nsISupports interface.
+     * Every XPCOM component needs to implement nsISupports, as it acts
+     * as the gateway to other interfaces this component implements.  You
+     * could manually declare QueryInterface, AddRef, and Release instead
+     * of using this macro, but why?
+     */
+    // nsISupports interface
+    NS_DECL_ISUPPORTS
+
+    /**
+     * This macro is defined in the nsISample.h file, and is generated
+     * automatically by the xpidl compiler.  It expands to
+     * declarations of all of the methods required to implement the
+     * interface.  xpidl will generate a NS_DECL_[INTERFACENAME] macro
+     * for each interface that it processes.
+     *
+     * The methods of nsISample are discussed individually below, but
+     * commented out (because this macro already defines them.)
+     */
+    NS_DECL_NSISAMPLE
+
+    /**
+     * The following is an explanation of how the interface header
+     * file expands to for a c++ implementation. NS_DELC_NSISAMPLE
+     * takes care of defining the right c++ implementation.
+     *
+     * The following if provided for more understanding.
+     *
+     * NS_IMETHOD expands to the standard XPCOM return type.  XPCOM methods
+     * should never return any other type.  The return value is used
+     * behind the scenes by the XPConnect runtime to figure out if the call
+     * failed in any way.
+     * These methods were generated by "attribute string Value" in 
+     * nsISample.idl.  When reflected into JavaScript, XPCOM will use these
+     * calls as Getter/Setter ops, so that they can be called transparently
+     * as "sample.Value='foo';" and "var val = sample.Value"
+     */
+    /* NS_IMETHOD GetValue(char * *aValue); */
+    /* NS_IMETHOD SetValue(char * aValue); */
+
+    /**
+     * The const came from the "in" specifier in nsISample.idl.  "in"
+     * specifies that the value of this parameter is used only for input,
+     * this method is not allowed to modify the contents of the buffer.
+     */
+    /* NS_IMETHOD WriteValue(const char *aPrefix); */
+
+    /**
+     * nsISample.idl specifies all of its string types as string, instead
+     * of wstring (wide string), the Unicode type.  If the world were a
+     * perfect place, all normal strings in XPCOM interfaces would be unicode.
+     * If this type had been specified as wstring, it would appear as
+     * char16_t * in C++, which is the NSPR type for unicode characters.
+     */
+    /* NS_IMETHOD Poke(const char* aValue); */
+
+private:
+    ~nsSampleImpl();
+
+    char* mValue;
+};
+
+#endif