Mercurial > hg
view contrib/win32/ReadMe.html @ 27142:060f83d219b9
extensions: refuse to load extensions if minimum hg version not met
As the author of several 3rd party extensions, I frequently see bug
reports from users attempting to run my extension with an old version
of Mercurial that I no longer support in my extension. Oftentimes, the
extension will import just fine. But as soon as we run extsetup(),
reposetup(), or get into the guts of a wrapped function, we encounter
an exception and abort. Today, Mercurial will print a message about
extensions that don't have a "testedwith" declaring explicit
compatibility with the current version.
The existing mechanism is a good start. But it isn't as robust as I
would like. Specifically, Mercurial assumes compatibility by default.
This means extension authors must perform compatibility checking in
their extsetup() or we wait and see if we encounter an abort at
runtime. And, compatibility checking can involve a lot of code and
lots of error checking. It's a lot of effort for extension authors.
Oftentimes, extension authors know which versions of Mercurial there
extension works on and more importantly where it is broken.
This patch introduces a magic "minimumhgversion" attribute in
extensions. When found, the extension loading mechanism will compare
the declared version against the current Mercurial version. If the
extension explicitly states we require a newer Mercurial version, a
warning is printed and the extension isn't loaded beyond importing
the Python module. This causes a graceful failure while alerting
the user of the compatibility issue.
I would be receptive to the idea of making the failure more fatal.
However, care would need to be taken to not criple every hg command.
e.g. the user may use `hg config` to fix the hgrc and if we aborted
trying to run that, the user would effectively be locked out of `hg`!
A potential future improvement to this functionality would be to catch
ImportError for the extension/module and parse the source code for
"minimumhgversion = 'XXX'" and do similar checking. This way we could
give more information about why the extension failed to load.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Tue, 24 Nov 2015 15:16:25 -0800 |
parents | 4b0fc75f9403 |
children | f6d73c8756e2 |
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>Mercurial for Windows</title> <meta http-equiv="Content-Type" content="text/html;charset=utf-8" > <style type="text/css"> <!-- html { font-family: sans-serif; margin: 1em 2em; } p { margin-top: 0.5em; margin-bottom: 0.5em; } pre { margin: 0.25em 0em; padding: 0.5em; background-color: #EEE; border: thin solid #CCC; } .indented { padding-left: 10pt; } --> </style> </head> <body> <h1>Mercurial for Windows</h1> <p>Welcome to Mercurial for Windows!</p> <p> Mercurial is a command-line application. You must run it from the Windows command prompt (or if you're hard core, a <a href="http://www.mingw.org/">MinGW</a> shell). </p> <p class="indented"> <i>Note: the standard <a href="http://www.mingw.org/">MinGW</a> msys startup script uses rxvt which has problems setting up standard input and output. Running bash directly works correctly.</i> </p> <p> For documentation, please visit the <a href="https://mercurial-scm.org/">Mercurial web site</a>. You can also download a free book, <a href="http://hgbook.red-bean.com/">Mercurial: The Definitive Guide</a>. </p> <p> By default, Mercurial installs to <tt>C:\Program Files\Mercurial</tt>. The Mercurial command is called <tt>hg.exe</tt>. </p> <h1>Testing Mercurial after you've installed it</h1> <p> The easiest way to check that Mercurial is installed properly is to just type the following at the command prompt: </p> <pre> hg </pre> <p> This command should print a useful help message. If it does, other Mercurial commands should work fine for you. </p> <h1>Configuration notes</h1> <h4>Default editor</h4> <p> The default editor for commit messages is 'notepad'. You can set the <tt>EDITOR</tt> (or <tt>HGEDITOR</tt>) environment variable to specify your preference or set it in <tt>mercurial.ini</tt>: </p> <pre> [ui] editor = whatever </pre> <h4>Configuring a Merge program</h4> <p> It should be emphasized that Mercurial by itself doesn't attempt to do a Merge at the file level, neither does it make any attempt to Resolve the conflicts. </p> <p> By default, Mercurial will use the merge program defined by the <tt>HGMERGE</tt> environment variable, or uses the one defined in the <tt>mercurial.ini</tt> file. (see <a href="https://mercurial-scm.org/wiki/MergeProgram">MergeProgram</a> on the Mercurial Wiki for more information) </p> <h1>Reporting problems</h1> <p> Before you report any problems, please consult the <a href="https://mercurial-scm.org/">Mercurial web site</a> and see if your question is already in our list of <a href="https://mercurial-scm.org/wiki/FAQ">Frequently Answered Questions</a> (the "FAQ"). </p> <p> If you cannot find an answer to your question, please feel free to send mail to the Mercurial mailing list, at <a href="mailto:mercurial@selenic.com">mercurial@selenic.com</a>. <b>Remember</b>, the more useful information you include in your report, the easier it will be for us to help you! </p> <p> If you are IRC-savvy, that's usually the fastest way to get help. Go to <tt>#mercurial</tt> on <tt>irc.freenode.net</tt>. </p> <h1>Author and copyright information</h1> <p> Mercurial was written by <a href="http://www.selenic.com">Matt Mackall</a>, and is maintained by Matt and a team of volunteers. </p> <p> The Windows installer was written by <a href="http://www.serpentine.com/blog">Bryan O'Sullivan</a>. </p> <p> Mercurial is Copyright 2005-2015 Matt Mackall and others. See the <tt>Contributors.txt</tt> file for a list of contributors. </p> <p> Mercurial is free software; you can redistribute it and/or modify it under the terms of the <a href="http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt">GNU General Public License version 2</a> or any later version. </p> <p> Mercurial is distributed in the hope that it will be useful, but <b>without any warranty</b>; without even the implied warranty of <b>merchantability</b> or <b>fitness for a particular purpose</b>. See the GNU General Public License for more details. </p> </body> </html>