I've been trying to use Mercurial Queues to manage my work on different tasks in several repositories. I try to name all my patches with the name of the bug it's related to; so for my recent work on getting Talos not skipping builds, I would call my patch 'bug468731'. I noticed that I was running this series of steps a lot: cd ~/mozilla/buildbot-configs hg qdiff > ~/patches/bug468731-buildbot-configs.patch cd ~/mozilla/buildbotcustom hg qdiff > ~/patches/bug468731-buildbotcustom.patch ...and then uploading the resulting patch files as attachments to the bug. There's a lot of repetition and extra mental work in those steps:

• I have to type the bug number manually twice. This is annoying, and error-prone. I've made a typo on more than one occasion and then wasted a few minutes trying to track down where the file went.
• I have to type the correct repository name for each patch. Again, I've managed to screw this up in the past. Often I have several terminals open, one for each repository, and I can get mixed up as to which repository I've currently got active.
• mercurial already knows the bug number, since I've used it in the name of my patch.
• mercurial already knows which repository I'm in.

I wrote the mercurial extension below to help with this. It will take the current patch name, and the basename of the current repository, and save a patch in ~/patches called [patch_name]-[repo_name].patch. It will also compare the current patch to any previous ones in the patches directory, and save a new file if the patches are different, or tell you that you've already saved this patch. To enable this extension, save the code below somewhere like ~/.hgext/mkpatch.py, and then add "mkpatch = ~/.hgext/mkpatch.py" to your .hgrc's extensions section. Then you can run 'hg mkpatch' to automatically create a patch for you in your ~/patches directory!

import os, hashlib



from mercurial import commands, util

from hgext import mq



def mkpatch(ui, repo, *pats, **opts):
    """Saves the current patch to a file called -.patch
    in your patch directory (defaults to ~/patches)
    """
    repo_name = os.path.basename(ui.config('paths', 'default'))
    if opts.get('patchdir'):
        patch_dir = opts.get('patchdir')
        del opts['patchdir']
    else:
        patch_dir = os.path.expanduser(ui.config('mkpatch', 'patchdir', "~/patches"))

    ui.pushbuffer()
    mq.top(ui, repo)
    patch_name = ui.popbuffer().strip()

    if not os.path.exists(patch_dir):
        os.makedirs(patch_dir)
    elif not os.path.isdir(patch_dir):
        raise util.Abort("%s is not a directory" % patch_dir)

    ui.pushbuffer()
    mq.diff(ui, repo, *pats, **opts)
    patch_data = ui.popbuffer()
    patch_hash = hashlib.new('sha1', patch_data).digest()

    full_name = os.path.join(patch_dir, "%s-%s.patch" % (patch_name, repo_name))
    i = 0
    while os.path.exists(full_name):
        file_hash = hashlib.new('sha1', open(full_name).read()).digest()
        if file_hash == patch_hash:
            ui.status("Patch is identical to ", full_name, "; not saving")
            return
        full_name = os.path.join(patch_dir, "%s-%s.patch.%i" % (patch_name, repo_name, i))
        i += 1

    open(full_name, "w").write(patch_data)
    ui.status("Patch saved to ", full_name)


mkpatch_options = [
        ("", "patchdir", '', "patch directory"),
        ]
cmdtable = {
    "mkpatch": (mkpatch, mkpatch_options + mq.cmdtable['^qdiff'][1], "hg mkpatch [OPTION]... [FILE]...")
}