Mercurial > hg
view mercurial/help/templates.txt @ 29375:fcaf20175b1b
demandimport: delay loading for "from a import b" with absolute_import
Before this patch, "from a import b" doesn't delay loading module "b",
if absolute_import is enabled, even though "from . import b" does.
For example:
- it is assumed that extension X has "from P import M" for module M
under package P with absolute_import feature
- if importing module M is already delayed before loading extension
X, loading module M in extension X is delayed until actually
referring
util, cmdutil, scmutil or so of Mercurial itself should be
imported by "from . import M" style before loading extension X
- otherwise, module M is loaded immediately at loading extension X,
even if extension X itself isn't used at that "hg" command invocation
Some minor modules (e.g. filemerge or so) of Mercurial itself
aren't imported by "from . import M" style before loading
extension X. And of course, external libraries aren't, too.
This might cause startup performance problem of hg command, because
many bundled extensions already enable absolute_import feature.
To delay loading module for "from a import b" with absolute_import
feature, this patch does below in "from a (or .a) import b" with
absolute_import case:
1. import root module of "name" by system built-in __import__
(referred as _origimport)
2. recurse down the module chain for hierarchical "name"
This logic can be shared with non absolute_import
case. Therefore, this patch also centralizes it into chainmodules().
3. and fall through to process elements in "fromlist" for the leaf
module of "name"
Processing elements in "fromlist" is executed in the code path
after "if _pypy: .... else: ..." clause. Therefore, this patch
replaces "if _pypy:" with "elif _pypy:" to share it.
At 4f1144c3c72b introducing original "work around" for "from a import
b" case, elements in "fromlist" were imported with "level=level". But
"level" might be grater than 1 (e.g. level=2 in "from .. import b"
case) at demandimport() invocation, and importing direct sub-module in
"fromlist" with level grater than 1 causes unexpected result.
IMHO, this seems main reason of "errors for unknown reason" described
in 4f1144c3c72b, and we don't have to worry about it, because this
issue was already fixed by 78d05778907b.
This is reason why this patch removes "errors for unknown reasons"
comment.
author | FUJIWARA Katsunori <foozy@lares.dti.ne.jp> |
---|---|
date | Sun, 19 Jun 2016 02:17:33 +0900 |
parents | df838803c1d4 |
children | a12d13eac513 |
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Mercurial allows you to customize output of commands through templates. You can either pass in a template or select an existing template-style from the command line, via the --template option. You can customize output for any "log-like" command: log, outgoing, incoming, tip, parents, and heads. Some built-in styles are packaged with Mercurial. These can be listed with :hg:`log --template list`. Example usage:: $ hg log -r1.0::1.1 --template changelog A template is a piece of text, with markup to invoke variable expansion:: $ hg log -r1 --template "{node}\n" b56ce7b07c52de7d5fd79fb89701ea538af65746 Strings in curly braces are called keywords. The availability of keywords depends on the exact context of the templater. These keywords are usually available for templating a log-like command: .. keywordsmarker The "date" keyword does not produce human-readable output. If you want to use a date in your output, you can use a filter to process it. Filters are functions which return a string based on the input variable. Be sure to use the stringify filter first when you're applying a string-input filter to a list-like input variable. You can also use a chain of filters to get the desired output:: $ hg tip --template "{date|isodate}\n" 2008-08-21 18:22 +0000 List of filters: .. filtersmarker Note that a filter is nothing more than a function call, i.e. ``expr|filter`` is equivalent to ``filter(expr)``. In addition to filters, there are some basic built-in functions: .. functionsmarker Also, for any expression that returns a list, there is a list operator:: expr % "{template}" As seen in the above example, ``{template}`` is interpreted as a template. To prevent it from being interpreted, you can use an escape character ``\{`` or a raw string prefix, ``r'...'``. New keywords and functions can be defined in the ``templatealias`` section of a Mercurial configuration file:: <alias> = <definition> Arguments of the form `a1`, `a2`, etc. are substituted from the alias into the definition. For example, :: [templatealias] r = rev rn = "{r}:{node|short}" leftpad(s, w) = pad(s, w, ' ', True) defines two symbol aliases, ``r`` and ``rn``, and a function alias ``leftpad()``. Some sample command line templates: - Format lists, e.g. files:: $ hg log -r 0 --template "files:\n{files % ' {file}\n'}" - Join the list of files with a ", ":: $ hg log -r 0 --template "files: {join(files, ', ')}\n" - Separate non-empty arguments by a " ":: $ hg log -r 0 --template "{separate(' ', node, bookmarks, tags}\n" - Modify each line of a commit description:: $ hg log --template "{splitlines(desc) % '**** {line}\n'}" - Format date:: $ hg log -r 0 --template "{date(date, '%Y')}\n" - Display date in UTC:: $ hg log -r 0 --template "{localdate(date, 'UTC')|date}\n" - Output the description set to a fill-width of 30:: $ hg log -r 0 --template "{fill(desc, 30)}" - Use a conditional to test for the default branch:: $ hg log -r 0 --template "{ifeq(branch, 'default', 'on the main branch', 'on branch {branch}')}\n" - Append a newline if not empty:: $ hg tip --template "{if(author, '{author}\n')}" - Label the output for use with the color extension:: $ hg log -r 0 --template "{label('changeset.{phase}', node|short)}\n" - Invert the firstline filter, i.e. everything but the first line:: $ hg log -r 0 --template "{sub(r'^.*\n?\n?', '', desc)}\n" - Display the contents of the 'extra' field, one per line:: $ hg log -r 0 --template "{join(extras, '\n')}\n" - Mark the active bookmark with '*':: $ hg log --template "{bookmarks % '{bookmark}{ifeq(bookmark, active, '*')} '}\n" - Find the previous release candidate tag, the distance and changes since the tag:: $ hg log -r . --template "{latesttag('re:^.*-rc$') % '{tag}, {changes}, {distance}'}\n" - Mark the working copy parent with '@':: $ hg log --template "{ifcontains(rev, revset('.'), '@')}\n" - Show details of parent revisions:: $ hg log --template "{revset('parents(%d)', rev) % '{desc|firstline}\n'}" - Show only commit descriptions that start with "template":: $ hg log --template "{startswith('template', firstline(desc))}\n" - Print the first word of each line of a commit message:: $ hg log --template "{word(0, desc)}\n"