/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ /* ***** BEGIN LICENSE BLOCK ***** * Version: NPL 1.1/GPL 2.0/LGPL 2.1 * * The contents of this file are subject to the Netscape Public License * Version 1.1 (the "License"); you may not use this file except in * compliance with the License. You may obtain a copy of the License at * http://www.mozilla.org/NPL/ * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is mozilla.org code. * * The Initial Developer of the Original Code is * Netscape Communications Corporation. * Portions created by the Initial Developer are Copyright (C) 1998 * the Initial Developer. All Rights Reserved. * * Contributor(s): * Pierre Phaneuf * * Alternatively, the contents of this file may be used under the terms of * either the GNU General Public License Version 2 or later (the "GPL"), or * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), * in which case the provisions of the GPL or the LGPL are applicable instead * of those above. If you wish to allow use of your version of this file only * under the terms of either the GPL or the LGPL, and not to allow others to * use your version of this file under the terms of the NPL, indicate your * decision by deleting the provisions above and replace them with the notice * and other provisions required by the GPL or the LGPL. If you do not delete * the provisions above, a recipient may use your version of this file under * the terms of any one of the NPL, the GPL or the LGPL. * * ***** END LICENSE BLOCK ***** */ /** * * A sample of XPConnect. This file contains an implementation nsSample * of the interface nsISample. * */ #include "plstr.h" #include "stdio.h" #include "nsSample.h" #include "nsMemory.h" //////////////////////////////////////////////////////////////////////// nsSampleImpl::nsSampleImpl() : mValue(nsnull) { NS_INIT_REFCNT(); mValue = PL_strdup("initial value"); } nsSampleImpl::~nsSampleImpl() { if (mValue) PL_strfree(mValue); } /** * NS_IMPL_ISUPPORTS1 expands to a simple implementation of the nsISupports * interface. This includes a proper implementation of AddRef, Release, * and QueryInterface. If this class supported more interfaces than just * nsISupports, * you could use NS_IMPL_ADDREF() and NS_IMPL_RELEASE() to take care of the * simple stuff, but you would have to create QueryInterface on your own. * nsSampleFactory.cpp is an example of this approach. * Notice that the second parameter to the macro is name of the interface, and * NOT the #defined IID. * * The _CI variant adds support for nsIClassInfo, which permits introspection * and interface flattening. */ NS_IMPL_ISUPPORTS1_CI(nsSampleImpl, nsISample); /** * Notice that in the protoype for this function, the NS_IMETHOD macro was * used to declare the return type. For the implementation, the return * type is declared by NS_IMETHODIMP */ NS_IMETHODIMP nsSampleImpl::GetValue(char** aValue) { NS_PRECONDITION(aValue != nsnull, "null ptr"); if (! aValue) return NS_ERROR_NULL_POINTER; if (mValue) { /** * GetValue's job is to return data known by an instance of * nsSampleImpl to the outside world. If we were to simply return * a pointer to data owned by this instance, and the client were to * free it, bad things would surely follow. * On the other hand, if we create a new copy of the data for our * client, and it turns out that client is implemented in JavaScript, * there would be no way to free the buffer. The solution to the * buffer ownership problem is the nsMemory singleton. Any buffer * returned by an XPCOM method should be allocated by the nsMemory. * This convention lets things like JavaScript reflection do their * job, and simplifies the way C++ clients deal with returned buffers. */ *aValue = (char*) nsMemory::Alloc(PL_strlen(mValue) + 1); if (! *aValue) return NS_ERROR_NULL_POINTER; PL_strcpy(*aValue, mValue); } else { *aValue = nsnull; } return NS_OK; } NS_IMETHODIMP nsSampleImpl::SetValue(const char* aValue) { NS_PRECONDITION(aValue != nsnull, "null ptr"); if (! aValue) return NS_ERROR_NULL_POINTER; if (mValue) { PL_strfree(mValue); } /** * Another buffer passing convention is that buffers passed INTO your * object ARE NOT YOURS. Keep your hands off them, unless they are * declared "inout". If you want to keep the value for posterity, * you will have to make a copy of it. */ mValue = PL_strdup(aValue); return NS_OK; } NS_IMETHODIMP nsSampleImpl::Poke(const char* aValue) { return SetValue((char*) aValue); } NS_IMETHODIMP nsSampleImpl::WriteValue(const char* aPrefix) { NS_PRECONDITION(aPrefix != nsnull, "null ptr"); if (! aPrefix) return NS_ERROR_NULL_POINTER; printf("%s %s\n", aPrefix, mValue); return NS_OK; }