Patchwork [3,of,5] ui: add a 'deprecwarn' helper to issue deprecation warnings

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Submitter Pierre-Yves David
Date Dec. 6, 2015, 8:45 p.m.
Message ID <4a7698acef2b110fc6b6.1449434713@marginatus.alto.octopoid.net>
Download mbox | patch
Permalink /patch/11863/
State Superseded
Commit f2cd240f2f7ce6ab8efe6389bc45640b9b47ecf6
Delegated to: Yuya Nishihara
Headers show

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Pierre-Yves David - Dec. 6, 2015, 8:45 p.m.
# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@fb.com>
# Date 1449385549 28800
#      Sat Dec 05 23:05:49 2015 -0800
# Node ID 4a7698acef2b110fc6b64c00db77e9ca2d82da76
# Parent  eca257699f241e8490ff79a0a2e869fd241ad596
# EXP-Topic deprecationwarning
# Available At http://hg.netv6.net/marmoute-wip/mercurial/
#              hg pull http://hg.netv6.net/marmoute-wip/mercurial/ -r 4a7698acef2b
ui: add a 'deprecwarn' helper to issue deprecation warnings

As discussed on the list, we are adding an official way to keep old API around
for a short time in order to help third party developer to catch up. The
deprecated API will issue developer warning (issued by default during test runs)
to warn extensions authors that they need to upgrade their code without
instantaneously breaking tool chains and normal users.

The version is passed as an explicit argument so that developer think about it
and a potential future script can automatically check for it.

This is not build as a decorator because accessing the 'ui' instance will likely
be different each time. The message is also free form because deprecated API are
replaced in a variety of ways. I'm not super happy about the final rendering of
that message, but this is a developer oriented warning and I would like to move
forward.

Patch

diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -1058,10 +1058,20 @@  class ui(object):
             curframe = inspect.currentframe()
             calframe = inspect.getouterframes(curframe, stacklevel)
             self.write_err('%s at: %s:%s (%s)\n'
                            % ((msg,) + calframe[stacklevel][1:4]))
 
+    def deprecwarn(self, msg, version):
+        """issue a deprecation warning
+
+        - msg: message explaining what is deprecated and how to upgrade,
+        - version: last version where the API will be supported,
+        """
+        msg += ("\n(compatibility will be dropped after Mercurial-%s,"
+                " update your code.)") % version
+        self.develwarn(msg, stacklevel=1)
+
 class paths(dict):
     """Represents a collection of paths and their configs.
 
     Data is initially derived from ui instances and the config files they have
     loaded.
diff --git a/tests/test-devel-warnings.t b/tests/test-devel-warnings.t
--- a/tests/test-devel-warnings.t
+++ b/tests/test-devel-warnings.t
@@ -45,10 +45,16 @@ 
   >     tr = repo.transaction('foobar')
   >     try:
   >         repair.strip(repo.ui, repo, [repo['.'].node()])
   >     finally:
   >         lo.release()
+  > @command('oldanddeprecated', [], '')
+  > def oldanddeprecated(ui, repo):
+  >     """test deprecation warning API"""
+  >     def foobar(ui):
+  >         ui.deprecwarn('foorbar is deprecated, go shopping', '42.1337')
+  >     foobar(ui)
   > 
   > def oldstylerevset(repo, subset, x):
   >     return list(subset)
   > 
   > revset.symbols['oldstyle'] = oldstylerevset
@@ -112,7 +118,10 @@ 
   [255]
 
   $ hg log -r "oldstyle()" -T '{rev}\n'
   devel-warn: revset "oldstyle" use list instead of smartset, (upgrade your code) at: */mercurial/revset.py:* (mfunc) (glob)
   0
+  $ hg oldanddeprecated
+  devel-warn: foorbar is deprecated, go shopping
+  (compatibility will be dropped after Mercurial-42.1337, update your code.) at: $TESTTMP/buggylocking.py:53 (oldanddeprecated)
 
   $ cd ..