Question

我一直在使用Python并遇到了一些必须经常发生的事情。我有五个陈述都属于提高的常见陷阱 FooException和BarException。我想运行它们，防范它们这些异常但即使在之后引发异常也会继续处理一些处理完成。现在，我可以这样做：

try:
    foo()
except (FooException, BarException):
    pass
try:
    bar()
except (FooException, BarException):
    pass
try:
    baz()
except (FooException, BarException):
    pass
try:
    spam()
except (FooException, BarException):
    pass
try:
    eggs()
except (FooException, BarException):
    pass

但这确实很冗长且极端违反DRY。相当蛮力显而易见的解决方案是这样的：

def wish_i_had_macros_for_this(statements, exceptions, gd, ld):                
    """ execute statements inside try/except handling exceptions with gd and ld
    as global dictionary and local dictionary

    statements is a list of strings to be executed as statements
    exceptions is a list of strings that resolve to Exceptions
    gd is a globals() context dictionary
    ld is a locals() context dictionary

    a list containing None or an Exception if an exception that wasn't 
    guarded against was raised during execution of the statement for each
    statement is returned
    """
    s = """ 
try:    
    $STATEMENT
except (%s):
    pass
""" % ','.join(exceptions)                                                     
    t = string.Template(s)
    code = [t.substitute({'STATEMENT': s}) for s in statements]                   
    elist = list() 
    for c in code:
        try:
            exec c in gd, ld
            elist.append(None)
        except Exception, e:
            elist.append(e)
    return elist

使用顺序：

>>> results = wish_i_had_macros_for_this(
                ['foo()','bar()','baz','spam()','eggs()'],
                ['FooException','BarException'],
                globals(),
                locals())
[None,None,None,SpamException,None]

有更好的方法吗？

Answer 1

这个怎么样？

 #!/usr/bin/env python

 def foo():
     print "foo"

 def bar():
     print "bar"

 def baz():
     print "baz"

 for f in [foo, bar, baz]:
     try:
         f()
     except (FooException, BarException):
         pass

Answer 2

def execute_silently(fn, exceptions = (FooException, BarException)):
    try:
        fn()
    except Exception as e:
        if not isinstance(e, exceptions):
            raise

execute_silently(foo)
execute_silently(bar)
# ...
# or even:
for fn in (foo, bar, ...):
    execute_silently(fn)

Answer 3

此版本也允许语句执行：

from contextlib import contextmanager
from functools import partial

@contextmanager
def exec_silent(exc=(StandardError,)):
    try:
        yield
    except exc:
        pass

silent_foobar = partial(exec_silent, (FooException, BarException))

with silent_foobar():
    print 'foo'
    foo()
with silent_foobar():
    print 'bar'
    bar()

Python异常控制/流问题

3 个答案: