[Yt-svn] yt: As per http://docs.python.org/reference/datamodel.html , __n...

[hg at spacepope.org]

hg Repository: yt
details:   yt/rev/be4139c3f9c2
changeset: 3561:be4139c3f9c2
user:      Matthew Turk <matthewturk at gmail.com>
date:
Wed Dec 01 08:21:09 2010 -0800
description:
As per http://docs.python.org/reference/datamodel.html , __new__ should return
a class that has not had __init__ called.  This is why parameter files are
almost always double-instantiated.  I have now moved the check_pf call to
inside the StaticOutput constructor, which should occur after
_parse_parameter_file and after the other states that it relies on have been
set.  This could result in two possible errors: check_pf could raise an
uncaught exception, or pickling could change.  I do not believe either of these
to be likely, and I have tested with the datasets I currently possess.

diffstat:

 yt/data_objects/static_output.py |  15 ++++++++-------
 1 files changed, 8 insertions(+), 7 deletions(-)

diffs (33 lines):

diff -r 20f28b6d9117 -r be4139c3f9c2 yt/data_objects/static_output.py
--- a/yt/data_objects/static_output.py	Sat Nov 27 07:52:28 2010 -0700
+++ b/yt/data_objects/static_output.py	Wed Dec 01 08:21:09 2010 -0800
@@ -57,13 +57,7 @@
         if not os.path.exists(apath): raise IOError(filename)
         if apath not in _cached_pfs:
             obj = object.__new__(cls)
-            obj.__init__(filename, *args, **kwargs)
             _cached_pfs[apath] = obj
-            if ytcfg.getboolean('yt','serialize'):
-                try:
-                    _pf_store.check_pf(obj)
-                except NoParameterShelf:
-                    pass
         return _cached_pfs[apath]
 
     def __init__(self, filename, data_style=None):
@@ -83,7 +77,14 @@
         self.parameters = {}
         self._parse_parameter_file()
         self._set_units()
-        # These can be taken out if you so desire
+        # Because we need an instantiated class to check the pf's existence in
+        # the cache, we move that check to here from __new__.  This avoids
+        # double-instantiation.
+        if ytcfg.getboolean('yt','serialize'):
+            try:
+                _pf_store.check_pf(obj)
+            except NoParameterShelf:
+                pass
 
     def __reduce__(self):
         args = (self._hash(),)