[Python-checkins] python/nondist/peps pep-0343.txt,1.4,1.5

[gvanrossum@users.sourceforge.net]

Update of /cvsroot/python/python/nondist/peps
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv17313

Modified Files:
	pep-0343.txt 
Log Message:
Slight elaboration for readers who don't recall PEP 310.


Index: pep-0343.txt
===================================================================
RCS file: /cvsroot/python/python/nondist/peps/pep-0343.txt,v
retrieving revision 1.4
retrieving revision 1.5
diff -u -d -r1.4 -r1.5
--- pep-0343.txt	14 May 2005 05:02:28 -0000	1.4
+++ pep-0343.txt	14 May 2005 05:08:23 -0000	1.5
@@ -37,18 +37,34 @@
     However, the with-statement of PEP 310 does *not* hide control
     flow, in my view: while a finally-suite temporarily suspends the
     control flow, in the end, the control flow resumes as if the
-    finally-suite wasn't there at all.  Consider this:
+    finally-suite wasn't there at all.
+
+    Remember, PEP 310 proposes rougly this syntax (the "VAR =" part is
+    optional):
 
         with VAR = EXPR:
+            BLOCK
+
+    which roughly translates into
+
+        VAR = EXPR
+        VAR.__enter__()
+        try:
+            BLOCK
+        finally:
+            VAR.__exit__()
+
+    Now consider this example:
+
+        with f = opening("/etc/passwd"):
             BLOCK1
         BLOCK2
 
     Here, just as if the first line was "if True" instead, we know
     that if BLOCK1 completes without an exception, BLOCK2 will be
-    reached; and if BLOCK1 raises an exception or executes a
-    non-local goto (a break, continue or return), BLOCK2 is *not*
-    reached.  The magic added by the with-statement at the end doesn't
-    affect this.
+    reached; and if BLOCK1 raises an exception or executes a non-local
+    goto (a break, continue or return), BLOCK2 is *not* reached.  The
+    magic added by the with-statement at the end doesn't affect this.
 
     (You may ask, what if a bug in the __exit__ method causes an
     exception?  Then all is lost -- but this is no worse than with