inspect
我正在为项目编写自定义日志系统。如果一个函数抛出异常,我想记录它的局部变量。是否可以从捕获异常的except块中访问提升函数的局部变量?例如:
def myfunction():
v1 = get_a_value()
raise Exception()
try:
myfunction()
except:
# can I access v1 from here?
如果知道异常处理代码将需要的值传递给异常,这通常是一种更干净的设计。但是,如果您正在编写调试器或类似的东西,则需要在不事先知道变量的情况下访问变量,则您可以在引发异常的上下文中访问任意变量: >def myfunction():
v1 = get_a_value()
raise Exception()
try:
myfunction()
except:
# can I access v1 from here?
v1 = inspect.trace()[-1][0].f_locals['v1']
trace
函数的功能及其处理的traceback
对象的格式在inspect
module documentation中描述。
inspect
您可以在框架对象中查找局部变量,可以从def myFunction() v1 = get_a_value() raise Exception(v1) try: myFunction() except Exception, e: v1 = e.args[0]
中获得。
sys.exc_info
根据异常在堆栈中的深度,您必须包括适当数量的>>> import sys >>> def f(a): ... b = a - 1 ... print 1.0 / b ... >>> try: ... f(1) ... except Exception, e: ... print sys.exc_info()[2].tb_next.tb_frame.f_locals ... {'a': 1, 'b': 0}
。是的,如果这是您自己的异常类型。像这样:
tb_next
>>> class MyExn(Exception): ... def __init__(self, val): ... self.val = val ... def __str__(self): ... print "something wrong with:", str(self.val) ... >>> def foo(): ... val = 42 ... raise MyExn(val) ... >>> foo() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 3, in foo __main__.MyExnsomething wrong with: 42 >>> # Or in a try block: >>> try: ... foo() ... except MyExn as e: ... print e.val ... 42 >>>
例如,在不使用try: myfunction() except: import sys type, value, tb = sys.exc_info() while tb.tb_next: tb = tb.tb_next frame = tb.tb_frame print frame.f_locals['v1']
且不使用“检查”之类的库的情况下用于“处理”异常。但是,我认为如果要“实际”处理异常,最好使用
raise Exception(some_def_var)
之类的东西。raise Exception(some_def_var)
。
inspect
def myFunction()
v1 = get_a_value()
raise Exception(v1)
try:
myFunction()
except Exception, e:
v1 = e.args[0]
中获得。>>> class MyExn(Exception):
... def __init__(self, val):
... self.val = val
... def __str__(self):
... print "something wrong with:", str(self.val)
...
>>> def foo():
... val = 42
... raise MyExn(val)
...
>>> foo()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 3, in foo
__main__.MyExnsomething wrong with: 42
>>> # Or in a try block:
>>> try:
... foo()
... except MyExn as e:
... print e.val
...
42
>>>
try:
myfunction()
except:
import sys
type, value, tb = sys.exc_info()
while tb.tb_next:
tb = tb.tb_next
frame = tb.tb_frame
print frame.f_locals['v1']
且不使用“检查”之类的库的情况下用于“处理”异常。