Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!ecngs!feeder2.ecngs.de!novso.com!newsfeed.xs4all.nl!newsfeed3.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path: <python.list@tim.thechases.com>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.008
X-Spam-Evidence: '*H*': 0.98; '*S*': 0.00; 'tests.': 0.07; 'mess': 0.09; 'messing': 0.09; 'subject:skip:c 10': 0.09; 'def': 0.12; '-tkc': 0.16; 'consolidate': 0.16; 'from:addr:python.list': 0.16; 'from:addr:tim.thechases.com': 0.16; 'from:name:tim chase': 0.16; 'lambda': 0.16; 'preexisting': 0.16; 'decorators': 0.24; 'passes': 0.24; 'fine': 0.24; "i've": 0.25; 'pass': 0.26; 'yields': 0.31; 'quite': 0.32; 'could': 0.34; 'something': 0.35; 'sequence': 0.36; 'charset:us-ascii': 0.36; 'to:addr:python-list': 0.38; 'to:addr:python.org': 0.39; 'results.': 0.60; 'different': 0.65; 'around,': 0.84; 'received:50.22': 0.84
Date: Tue, 29 Oct 2013 11:54:27 -0500
From: Tim Chase <python.list@tim.thechases.com>
To: python-list@python.org
Subject: stacked decorators and consolidating
X-Mailer: Claws Mail 3.8.1 (GTK+ 2.24.10; x86_64-pc-linux-gnu)
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
X-AntiAbuse: This header was added to track abuse, please include it with any abuse report
X-AntiAbuse: Primary Hostname - boston.accountservergroup.com
X-AntiAbuse: Original Domain - python.org
X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12]
X-AntiAbuse: Sender Address Domain - tim.thechases.com
X-Get-Message-Sender-Via: boston.accountservergroup.com: authenticated_id: tim@thechases.com
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe: <https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive: <http://mail.python.org/pipermail/python-list/>
List-Post: <mailto:python-list@python.org>
List-Help: <mailto:python-list-request@python.org?subject=help>
List-Subscribe: <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups: comp.lang.python
Message-ID: <mailman.1765.1383065569.18130.python-list@python.org>
Lines: 33
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1383065569 news.xs4all.nl 16003 [2001:888:2000:d::a6]:44120
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:57933

I've got some decorators that work fine as such:

  @dec1(args1)
  @dec2(args2)
  @dec3(args3)
  def myfun(...):
    pass

However, I used that sequence quite a bit, so I figured I could do
something like

  dec_all = dec1(args1)(dec2(args2)(dec3(args3)))

to consolidate the whole mess down to

  @dec_all
  def myfun(...):
    pass

However, this yields different (test-breaking) results.  Messing
around, I found that if I write it as

  dec_all = lambda fn: dec1(args1)(dec2(args2)(dec3(args3)(fn)))

it works and passes all preexisting tests.

What am I missing that would cause this difference in behavior?

-tkc