Add the ability to use the "with" statement on ESFile.

--HG--
extra : convert_revision : svn%3Aeff31bef-be4a-0410-a8fe-e47997df2690/trunk%4049

python/rundoctest.py

@@ -35,7 +35,15 @@ def main():
     print 'underlying C library, and are not "seen" (or hidden) by doctest.'
     print
 
-    (failures,tests) = doctest.testfile(filename,verbose=verbose)
+    # I want to be able to use the "with" statement in the doctests.
+    # It's not possible to use "from __future__ import with_statement"
+    # in doctests as such. Instead, one has to add the resulting globals
+    # to the doctest context. Which seems to be done as follows:
+    import __future__
+    extraglobs={'with_statement':__future__.with_statement}
+
+    (failures,tests) = doctest.testfile(filename,verbose=verbose,
+                                        extraglobs=extraglobs)
 
     testword = "test"
     if tests != 1: testword = "tests"

python/test.txt

@@ -1,6 +1,5 @@
 Some tests for the Python binding of the TS tools
 =================================================
-
 We shall assume that our standard sample data has been downloaded and expanded
 into our sibling ``data`` directory. See the ``../data/setup.sh`` script.
 
@@ -242,6 +241,22 @@ OK. So ``seek()`` returns a tuple of (infile,inpacket), whilst the
 what each field means, because it *is* impossible to decide rationally which
 order they should come in.
 
+The "with" syntax should also work:
+
+    >>> count = 0
+    >>> with ESFile(test_es_file) as f:
+    ...    for unit in f:
+    ...        count += 1
+    ...        print unit
+    ...        if count > 5:
+    ...            break
+    ES unit: start code 00, len    9: 00 00 01 00 01 df ff fb b8
+    ES unit: start code b5, len    9: 00 00 01 b5 85 45 4b 5d 80
+    ES unit: start code 01, len 1645: 00 00 01 01 0a b0 10 09...
+    ES unit: start code 02, len 1634: 00 00 01 02 0a b0 10 09...
+    ES unit: start code 03, len   16: 00 00 01 03 0a b0 10 07...
+    ES unit: start code 04, len   15: 00 00 01 04 0a b0 10 02...
+
 
 // Local Variables:
 // tab-width: 8

python/tstools.pyx

@@ -473,6 +473,19 @@ cdef class ESFile:
         self.name = None
         self.mode = None
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, etype, value, tb):
+        if tb is None:
+            # No exception, so just finish normally
+            self.close()
+        else:
+            # Exception occurred, so tidy up
+            self.close()
+            # And allow the exception to be re-raised
+            return False
+
 # ----------------------------------------------------------------------
 # vim: set filetype=python expandtab shiftwidth=4:
 # [X]Emacs local variables declaration - place us into python mode