"tomer filiba" <[EMAIL PROTECTED]> wrote:
> "[" <expr> for <expr> in <expr> [if <cond>] [except
> <exception-class-or-tuple>: <action>] "]"
Note that of the continue cases you offer, all of them are merely simple
if condition (though the file example could use a better test than
os.path.isfile).
[x for x in a if x.startswith("y") except AttributeError: continue]
[x for x in a if hasattr(x, 'startswith') and x.startswith("y")]
[1.0 / x for x in y except ZeroDivisionError: continue]
[1.0 / x for x in y if x != 0]
[open(filename) for filename in filelist except IOError: continue]
[open(filename) for filename in filelist if os.path.isfile(filename)]
The break case can be implemented with particular kind of instance
object, though doesn't have the short-circuiting behavior...
class StopWhenFalse:
def __init__(self):
self.t = 1
def __call__(self, t):
if not t:
self.t = 0
return 0
return self.t
z = StopWhenFalse()
Assuming you create a new instance z of StopWhenFalse before doing the
list comprehensions...
[x for x in a if z(hasattr(x, 'startswith') and x.startswith("y"))]
[1.0 / x for x in y if z(x != 0)]
[open(filename) for filename in filelist if z(os.path.isfile(filename))]
If you couldn't guess; -1, you can get equivalent behavior without
complicating the generator expression/list comprension syntax.
- Josiah
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