From 8d65b505d832ba4d6e4ad8a612c69377303a1772 Mon Sep 17 00:00:00 2001
From: Ned Batchelder <ned@nedbatchelder.com>
Date: Tue, 12 May 2009 21:12:09 -0400
Subject: Give the singleton module interface a way to keep the old behavior of
 auto-loading and -saving data as needed.

---
 CHANGES.txt           |  6 ++++--
 coverage/__init__.py  |  2 +-
 coverage/control.py   | 14 +++++++++++++-
 test/test_coverage.py |  3 +--
 4 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index 76fcb3cf..be8505eb 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -17,8 +17,10 @@ Version 3.0b3
   installed after compiling are now located correctly.  Thanks, Detlev
   Offenbach.
 
-- Removed the automatic saving of data on process exit.  If you needed this,
-  please get in touch with me so I can understand why!
+- When using the object api (that is, constructing a coverage() object), data
+  is no longer saved automatically on process exit.  If you needed this,
+  please get in touch with me so I can understand why!  The module-level
+  interface still uses automatic saving.
 
 
 Version 3.0b2, 30 April 2009
diff --git a/coverage/__init__.py b/coverage/__init__.py
index c787b341..bce40406 100644
--- a/coverage/__init__.py
+++ b/coverage/__init__.py
@@ -33,7 +33,7 @@ def _singleton_method(name):
         """Singleton wrapper around a coverage method."""
         global _the_coverage
         if not _the_coverage:
-            _the_coverage = coverage()
+            _the_coverage = coverage(auto_data=True)
         return getattr(_the_coverage, name)(*args, **kwargs)
     return wrapper
 
diff --git a/coverage/control.py b/coverage/control.py
index 32e6fad3..dab9eca4 100644
--- a/coverage/control.py
+++ b/coverage/control.py
@@ -14,7 +14,8 @@ class coverage:
     """Programmatic access to Coverage.
     
     """
-    def __init__(self, data_file=None, data_suffix=False, cover_pylib=False):
+    def __init__(self, data_file=None, data_suffix=False, cover_pylib=False,
+                auto_data=False):
         """Create a new coverage measurement context.
         
         `data_file` is the base name of the data file to use, defaulting to
@@ -26,11 +27,17 @@ class coverage:
         with the Python interpreter is measured.  This includes the Python
         standard library and any packages installed with the interpreter.
         
+        If `auto_data` is true, then any existing data file will be read when
+        coverage measurement starts, and data will be saved automatically when
+        measurement stops.
+        
         """
         from coverage.collector import Collector
         from coverage import __version__
         
         self.cover_pylib = cover_pylib
+        self.auto_data = auto_data
+        
         self.exclude_re = ""
         self.exclude_list = []
         
@@ -105,6 +112,11 @@ class coverage:
         
     def start(self):
         """Start measuring code coverage."""
+        if self.auto_data:
+            self.load()
+            # Save coverage data when Python exits.
+            import atexit
+            atexit.register(self.save)
         self.collector.start()
         
     def stop(self):
diff --git a/test/test_coverage.py b/test/test_coverage.py
index 8a10dce4..2c0aed4a 100644
--- a/test/test_coverage.py
+++ b/test/test_coverage.py
@@ -1552,8 +1552,7 @@ if sys.hexversion >= 0x020500f0:
 
 class ModuleTest(CoverageTest):
     def testNotSingleton(self):
-        """ You *can* create another coverage object.
-        """
+        # You *can* create another coverage object.
         coverage.coverage()
         coverage.coverage()
 
-- 
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