Use a single pyexec() utility function to fix compatibility issues

djc · djc · commit 8fdba0f09df0 · 2014-07-24T11:43:52.000+02:00
While the current setup (where 2.x uses the exec statement and 3.x uses the
exec() function) works at run-time, it causes problem while byte-compiling
the util modules for their non-appropriate interpreter versions:

File "/usr/lib64/python2.7/site-packages/couchdb/util3.py", line 17
  pyexec = exec
              ^
SyntaxError: invalid syntax

File "/usr/lib64/python3.3/site-packages/couchdb/util2.py", line 19
  exec code in gns, lns
          ^
SyntaxError: invalid syntax

There doesn't appear to be an easy way to exclude some files from installation
based on the installing Python version, but it turns out the 2.x exec
statement can also take its arguments as a tuple, such that the 2.x and 3.x
versions can be used with the same syntax.

However, Python 2.7 has a bug (#21591) that prevents this from working in the
context we use exec in (in a function that also contains a nested function),
due to a bad implementation that enables the arguments-as-tuple functionality.
We thus need a helper function after all, to pull it out of that context.
diff --git a/couchdb/util.py b/couchdb/util.py
@@ -4,3 +4,7 @@
     from couchdb.util2 import *
 else:
     from couchdb.util3 import *
+
+def pyexec(code, gns, lns):
+    # http://bugs.python.org/issue21591
+    exec(code, gns, lns)
diff --git a/couchdb/util2.py b/couchdb/util2.py
@@ -1,8 +1,7 @@
 
 __all__ = [
     'StringIO', 'urlsplit', 'urlunsplit', 'urlquote', 'urlunquote',
-    'urlencode', 'utype', 'ltype', 'pyexec', 'strbase', 'funcode',
-    'urlparse',
+    'urlencode', 'utype', 'ltype', 'strbase', 'funcode', 'urlparse',
 ]
 
 utype = unicode
@@ -15,8 +14,5 @@
 from urllib import unquote as urlunquote
 from urllib import urlencode
 
-def pyexec(code, gns, lns):
-    exec code in gns, lns
-
 def funcode(fun):
     return fun.func_code
diff --git a/couchdb/util3.py b/couchdb/util3.py
@@ -1,8 +1,7 @@
 
 __all__ = [
     'StringIO', 'urlsplit', 'urlunsplit', 'urlquote', 'urlunquote',
-    'urlencode', 'utype', 'ltype', 'pyexec', 'strbase', 'funcode',
-    'urlparse',
+    'urlencode', 'utype', 'ltype', 'strbase', 'funcode', 'urlparse',
 ]
 
 utype = str
@@ -14,7 +13,5 @@
 from urllib.parse import quote as urlquote
 from urllib.parse import unquote as urlunquote
 
-pyexec = exec
-
 def funcode(fun):
     return fun.__code__
