@contextlib question

[Neal Becker]

http://www.python.org/doc/2.5.2/lib/module-contextlib.html has this example:
from contextlib import contextmanager

@contextmanager
def tag(name):
print "<%s>" % name
yield
print "</%s>" % name

contexlib.contextmanager doc string (2.5.1) says:
Typical usage:

@contextmanager
def some_generator(<arguments>):
<setup>
try:
yield <value>
finally:
<cleanup>

Should I use the 'try', and 'finally' as in the 2nd example, or should I use the first example? Does it matter?

 

[Peter Otten]

http://www.python.org/doc/2.5.2/lib/module-contextlib.html has this
example: from contextlib import contextmanager

@contextmanager
def tag(name):
print "<%s>" % name
yield
print "</%s>" % name

contexlib.contextmanager doc string (2.5.1) says:
Typical usage:

@contextmanager
def some_generator(<arguments>):
<setup>
try:
yield <value>
finally:
<cleanup>

Should I use the 'try', and 'finally' as in the 2nd example, or should I
use the first example? Does it matter?

These examples are basically the same. try...finally does what it always
does -- ensure that the cleanup code is executed even if an exception
occurs in the try block. So

with some_generator(...):
    1/0

will execute <cleanup> whereas

with tag("yadda"):
    1/0

will print <yadda> but not </yadda>. (Both will raise the ZeroDivisionError)

Peter