pure: provide more correct implementation of posixfile for Windows
requires ctypes
Why is posixfile a class?
Because the implementation needs to use the Python library call os.fdopen [1],
which sets the 'name' attribute on the Python file object it creates to the
mostly meaningless string '<fdopen>', since file descriptors don't have a name.
But users of posixfile depend on the name attribute [2] being set to a proper
value, like Python's built-in 'open' function sets it on file objects.
Python file's name attribute is read-only, so we can't just assign to it after
the file object has alrady been created.
To solve this problem, we save the name of the file on a wrapper object,
and delegate the file function calls to the wrapped (private) file object
using __getattr__.
[1] http://docs.python.org/library/os.html#os.fdopen
[2] http://docs.python.org/library/stdtypes.html#file.name
$ hg init
$ mkdir alpha
$ touch alpha/one
$ mkdir beta
$ touch beta/two
$ hg add alpha/one beta/two
$ hg ci -m "start"
$ echo 1 > alpha/one
$ echo 2 > beta/two
everything
$ hg diff --nodates
diff -r 7d5ef1aea329 alpha/one
--- a/alpha/one
+++ b/alpha/one
@@ -0,0 +1,1 @@
+1
diff -r 7d5ef1aea329 beta/two
--- a/beta/two
+++ b/beta/two
@@ -0,0 +1,1 @@
+2
beta only
$ hg diff --nodates beta
diff -r 7d5ef1aea329 beta/two
--- a/beta/two
+++ b/beta/two
@@ -0,0 +1,1 @@
+2
inside beta
$ cd beta
$ hg diff --nodates .
diff -r 7d5ef1aea329 beta/two
--- a/beta/two
+++ b/beta/two
@@ -0,0 +1,1 @@
+2