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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 03:01:46 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 03:01:46 +0000 |
| commit | f8fe689a81f906d1b91bb3220acde2a4ecb14c5b (patch) | |
| tree | 26484e9d7e2c67806c2d1760196ff01aaa858e8c /src/libs/xpcom18a4/python/doc/architecture.html | |
| parent | Initial commit. (diff) | |
| download | virtualbox-upstream.tar.xz virtualbox-upstream.zip | |
Adding upstream version 6.0.4-dfsg.upstream/6.0.4-dfsgupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/libs/xpcom18a4/python/doc/architecture.html')
| -rw-r--r-- | src/libs/xpcom18a4/python/doc/architecture.html | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/src/libs/xpcom18a4/python/doc/architecture.html b/src/libs/xpcom18a4/python/doc/architecture.html new file mode 100644 index 00000000..d12a2a76 --- /dev/null +++ b/src/libs/xpcom18a4/python/doc/architecture.html @@ -0,0 +1,116 @@ +<html> +<!-- ***** BEGIN LICENSE BLOCK ***** + - Version: MPL 1.1/GPL 2.0/LGPL 2.1 + - + - The contents of this file are subject to the Mozilla 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/MPL/ + - + - 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 PyXPCOM. + - + - The Initial Developer of the Original Code is + - ActiveState Tool Corporation. + - Portions created by the Initial Developer are Copyright (C) 2000-2001 + - the Initial Developer. All Rights Reserved. + - + - Contributor(s): + - + - 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 MPL, indicate your + - decision by deleting the provisions above and replace them with the notice + - and other provisions required by the LGPL or the GPL. 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 MPL, the GPL or the LGPL. + - + - ***** END LICENSE BLOCK ***** --> + +<head> +<meta http-equiv="Content-Type" content="text/html; charset=windows-1252"> +<meta name="GENERATOR" content="Microsoft FrontPage 4.0"> +<meta name="ProgId" content="FrontPage.Editor.Document"> +<title>Architecture</title> +</head> + +<body> + +<h1>Python XPCOM Package Architecture</h1> +<h2><a name="Architecture">Architecture</a></h2> +<p>Much of the design for the Python XPCOM Package has been borrowed from the Python MS-COM +extensions in <i>win32com</i>. Most of the major limitations and drawbacks in the <i>win32com</i> +design have been addressed, mainly "auto-wrapping" of +interface objects, which is not supported by <i>win32com</i>.</p> +<p>Like <i>win32com</i>, this architecture includes the concept of <i>client COM</i> and <i>server +COM.</i> </p> +<p>Client COM:</p> +<ul> + <li>calls other interfaces</li> + <li>is supported by <i>PyInterfaces</i> implemented in C++, which assists +in making the COM calls</li> + <li>is supported by <i>PyGateways</i>, which assists in receiving +external COM calls and dispatching them to the correct Python object</li> + <li> is supported in the <i>xpcom/client</i> package</li> +</ul> +<p>Server COM:</p> +<ul> + <li>implements interfaces for use by other XPCOM applications or components</li> + <li> is +supported in the <i>xpcom/server</i> package</li> +</ul> +<p>The XPConnect framework is very powerful, and far exceeds what COM's <i> +IDispatch</i> can offer. Thus, we are able to get by with far fewer interfaces +supported in the C++ level, and defer most things to the Python code that uses +XPConnect. As a result, the requirement for a huge number of interfaces to +exist in the <i>.pyd</i> does not exist. There are, however, a number of +interfaces that do require native C++ support: these are interfaces +required to "boot" the XPConnect support (i.e., the interfaces that are +used to get information about interfaces), and also two gateways that need to +work without interface information available. This last requirement is +due to the XPCOM shutdown-ordering - it may be a bug, but is not an unreasonable +amount of code anyway.</p> +<p><b>Auto-wrapping</b> of COM objects is supported by both client COM and +server COM. For client COM, auto-wrapping means that the +Python programmer always sees Python "component" objects, rather than +raw C++ interface objects; to the user, it all appears to "just +work". This is a major source of frustration in the <i>win32com</i> +framework.</p> +<p>For server COM, auto-wrapping means that you can +pass Python instances wherever a COM object is expected. If the Python +instance supports COM interfaces, by virtue of having a <i>_com_interfaces_</i> +attribute that lists the interface requested, it will be automatically wrapped +in the correct COM object. </p> +<p><b>Error Handling:</b> The C++ framework has good error handling support, +and uses the XPCOM console service to log debug messages, Python exceptions and +tracebacks. <i>win32com</i> does not have good exception/traceback support +at the C++ level, mainly because COM does not define a service like +the console where debug messages can go. This does mean that in Mozilla +release builds, these debug messages are likely to be lost, but the <i>--console</i> +command line option to a release Mozilla will get them back. Therefore, +the other error-support utilities, such as the error callbacks made on the +policy object, may be used.</p> +<p><b>Component Loader, Modules and Factories:</b> XPCOM has the concept +of a component loader - a module used to load all components of a +particular type. For example, the <i>moz.jsloader.1</i> component loads all +the JavaScript components. Similarly, the <i>moz.pyloader.1</i> +component loads all Python components. However, unlike +JavaScript, the Python component loader is actually implemented in Python +itself! Since the Python component loader can not be used to load +itself, this component has some special code, <i>pyloader.dll,</i> to boot-strap itself.</p> +<p>This means is that all XPCOM components, including the Python loader itself and all +XPCOM module and factory interfaces, are implemented in +Python. <b>There are no components or interfaces implemented purely in C++ +in this entire package!</b></p> + +</body> + +</html> |