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diff mercurial/commands.py @ 37716:dfc51a482031

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registrar: replace "cmdtype" with an intent-based mechanism (API) Commands perform varied actions and repositories vary in their capabilities. Historically, the .hg/requires file has been used to lock out clients lacking a requirement. But this is a very heavy-handed approach and is typically reserved for cases where the on-disk storage format changes and we want to prevent incompatible clients from operating on a repo. Outside of the .hg/requires file, we tend to deal with things like optional, extension-provided features via checking at call sites. We'll either have checks in core or extensions will monkeypatch functions in core disabling incompatible features, enabling new features, etc. Things are somewhat tolerable today. But once we introduce alternate storage backends with varying support for repository features and vastly different modes of behavior, the current model will quickly grow unwieldy. For example, the implementation of the "simple store" required a lot of hacks to deal with stripping and verify because various parts of core assume things are implemented a certain way. Partial clone will require new ways of modeling file data retrieval, because we can no longer assume that all file data is already local. In this new world, some commands might not make any sense for certain types of repositories. What we need is a mechanism to affect the construction of repository (and eventually peer) instances so the requirements/capabilities needed for the current operation can be taken into account. "Current operation" can almost certainly be defined by a command. So it makes sense for commands to declare their intended actions. This commit introduces the "intents" concept on the command registrar. "intents" captures a set of strings that declare actions that are anticipated to be taken, requirements the repository must possess, etc. These intents will be passed into hg.repo(), which will pass them into localrepository, where they can be used to influence the object being created. Some use cases for this include: * For read-only intents, constructing a repository object that doesn't expose methods that can mutate the repository. Its VFS instances don't even allow opening a file with write access. * For read-only intents, constructing a repository object without cache invalidation logic. If the repo never changes during its lifetime, nothing ever needs to be invalidated and we don't need to do expensive things like verify the changelog's hidden revisions state is accurate every time we access repo.changelog. * We can automatically hide commands from `hg help` when the current repository doesn't provide that command. For example, an alternate storage backend may not support `hg commit`, so we can hide that command or anything else that would perform local commits. We already kind of had an "intents" mechanism on the registrar in the form of "cmdtype." However, it was never used. And it was limited to a single value. We really need something that supports multiple intents. And because intents may be defined by extensions and at this point are advisory, I think it is best to define them in a set rather than as separate arguments/attributes on the command. Differential Revision: https://phab.mercurial-scm.org/D3376
author Gregory Szorc <gregory.szorc@gmail.com>
date Sat, 14 Apr 2018 09:23:48 -0700
parents 5fc502e149f1
children e7bf5a73e4e1
line wrap: on
line diff
--- a/mercurial/commands.py	Sat Apr 14 11:20:38 2018 -0400
+++ b/mercurial/commands.py	Sat Apr 14 09:23:48 2018 -0700
@@ -73,7 +73,7 @@
 table.update(debugcommandsmod.command._table)
 
 command = registrar.command(table)
-readonly = registrar.command.readonly
+INTENT_READONLY = registrar.INTENT_READONLY
 
 # common command options
 
@@ -1083,7 +1083,8 @@
       _('show only branches that have unmerged heads (DEPRECATED)')),
      ('c', 'closed', False, _('show normal and closed branches')),
     ] + formatteropts,
-    _('[-c]'), cmdtype=readonly)
+    _('[-c]'),
+    intents={INTENT_READONLY})
 def branches(ui, repo, active=False, closed=False, **opts):
     """list repository named branches
 
@@ -1282,7 +1283,8 @@
     ('', 'decode', None, _('apply any matching decode filter')),
     ] + walkopts + formatteropts,
     _('[OPTION]... FILE...'),
-    inferrepo=True, cmdtype=readonly)
+    inferrepo=True,
+    intents={INTENT_READONLY})
 def cat(ui, repo, file1, *pats, **opts):
     """output the current or given revision of files
 
@@ -1633,7 +1635,8 @@
      ('l', 'local', None, _('edit repository config')),
      ('g', 'global', None, _('edit global config'))] + formatteropts,
     _('[-u] [NAME]...'),
-    optionalrepo=True, cmdtype=readonly)
+    optionalrepo=True,
+    intents={INTENT_READONLY})
 def config(ui, repo, *values, **opts):
     """show combined config settings from all hgrc files
 
@@ -1802,7 +1805,8 @@
     ('c', 'change', '', _('change made by revision'), _('REV'))
     ] + diffopts + diffopts2 + walkopts + subrepoopts,
     _('[OPTION]... ([-c REV] | [-r REV1 [-r REV2]]) [FILE]...'),
-    inferrepo=True, cmdtype=readonly)
+    inferrepo=True,
+    intents={INTENT_READONLY})
 def diff(ui, repo, *pats, **opts):
     """diff repository (or selected files)
 
@@ -1895,7 +1899,8 @@
     ('', 'switch-parent', None, _('diff against the second parent')),
     ('r', 'rev', [], _('revisions to export'), _('REV')),
     ] + diffopts + formatteropts,
-    _('[OPTION]... [-o OUTFILESPEC] [-r] [REV]...'), cmdtype=readonly)
+    _('[OPTION]... [-o OUTFILESPEC] [-r] [REV]...'),
+    intents={INTENT_READONLY})
 def export(ui, repo, *changesets, **opts):
     """dump the header and diffs for one or more changesets
 
@@ -1990,7 +1995,8 @@
     [('r', 'rev', '', _('search the repository as it is in REV'), _('REV')),
      ('0', 'print0', None, _('end filenames with NUL, for use with xargs')),
     ] + walkopts + formatteropts + subrepoopts,
-    _('[OPTION]... [FILE]...'), cmdtype=readonly)
+    _('[OPTION]... [FILE]...'),
+    intents={INTENT_READONLY})
 def files(ui, repo, *pats, **opts):
     """list tracked files
 
@@ -2371,7 +2377,8 @@
     ('d', 'date', None, _('list the date (short with -q)')),
     ] + formatteropts + walkopts,
     _('[OPTION]... PATTERN [FILE]...'),
-    inferrepo=True, cmdtype=readonly)
+    inferrepo=True,
+    intents={INTENT_READONLY})
 def grep(ui, repo, pattern, *pats, **opts):
     """search revision history for a pattern in specified files
 
@@ -2617,7 +2624,8 @@
     ('a', 'active', False, _('show active branchheads only (DEPRECATED)')),
     ('c', 'closed', False, _('show normal and closed branch heads')),
     ] + templateopts,
-    _('[-ct] [-r STARTREV] [REV]...'), cmdtype=readonly)
+    _('[-ct] [-r STARTREV] [REV]...'),
+    intents={INTENT_READONLY})
 def heads(ui, repo, *branchrevs, **opts):
     """show branch heads
 
@@ -2693,7 +2701,8 @@
      ('s', 'system', [], _('show help for specific platform(s)')),
      ],
     _('[-ecks] [TOPIC]'),
-    norepo=True, cmdtype=readonly)
+    norepo=True,
+    intents={INTENT_READONLY})
 def help_(ui, name=None, **opts):
     """show help for a given topic or a help overview
 
@@ -2735,7 +2744,8 @@
     ('B', 'bookmarks', None, _('show bookmarks')),
     ] + remoteopts + formatteropts,
     _('[-nibtB] [-r REV] [SOURCE]'),
-    optionalrepo=True, cmdtype=readonly)
+    optionalrepo=True,
+    intents={INTENT_READONLY})
 def identify(ui, repo, source=None, rev=None,
              num=None, id=None, branch=None, tags=None, bookmarks=None, **opts):
     """identify the working directory or specified revision
@@ -3312,7 +3322,8 @@
      _('do not display revision or any of its ancestors'), _('REV')),
     ] + logopts + walkopts,
     _('[OPTION]... [FILE]'),
-    inferrepo=True, cmdtype=readonly)
+    inferrepo=True,
+    intents={INTENT_READONLY})
 def log(ui, repo, *pats, **opts):
     """show revision history of entire repository or files
 
@@ -3480,7 +3491,8 @@
     [('r', 'rev', '', _('revision to display'), _('REV')),
      ('', 'all', False, _("list files from all revisions"))]
          + formatteropts,
-    _('[-r REV]'), cmdtype=readonly)
+    _('[-r REV]'),
+    intents={INTENT_READONLY})
 def manifest(ui, repo, node=None, rev=None, **opts):
     """output the current or given revision of the project manifest
 
@@ -3758,7 +3770,7 @@
     displayer.close()
 
 @command('paths', formatteropts, _('[NAME]'), optionalrepo=True,
-    cmdtype=readonly)
+    intents={INTENT_READONLY})
 def paths(ui, repo, search=None, **opts):
     """show aliases for remote repositories
 
@@ -4696,7 +4708,7 @@
     return repo.rollback(dryrun=opts.get(r'dry_run'),
                          force=opts.get(r'force'))
 
-@command('root', [], cmdtype=readonly)
+@command('root', [], intents={INTENT_READONLY})
 def root(ui, repo):
     """print the root (top) of the current working directory
 
@@ -4790,7 +4802,8 @@
     ('', 'change', '', _('list the changed files of a revision'), _('REV')),
     ] + walkopts + subrepoopts + formatteropts,
     _('[OPTION]... [FILE]...'),
-    inferrepo=True, cmdtype=readonly)
+    inferrepo=True,
+    intents={INTENT_READONLY})
 def status(ui, repo, *pats, **opts):
     """show changed files in the working directory
 
@@ -4958,7 +4971,8 @@
 
 @command('^summary|sum',
     [('', 'remote', None, _('check for push and pull'))],
-    '[--remote]', cmdtype=readonly)
+    '[--remote]',
+    intents={INTENT_READONLY})
 def summary(ui, repo, **opts):
     """summarize working directory state
 
@@ -5359,7 +5373,7 @@
     finally:
         release(lock, wlock)
 
-@command('tags', formatteropts, '', cmdtype=readonly)
+@command('tags', formatteropts, '', intents={INTENT_READONLY})
 def tags(ui, repo, **opts):
     """list repository tags
 
@@ -5596,7 +5610,8 @@
     """
     return hg.verify(repo)
 
-@command('version', [] + formatteropts, norepo=True, cmdtype=readonly)
+@command('version', [] + formatteropts, norepo=True,
+         intents={INTENT_READONLY})
 def version_(ui, **opts):
     """output version and copyright information"""
     opts = pycompat.byteskwargs(opts)