Serdar Tumgoren wrote:
>> An "if" test would be more readable, I agree. But I was trying to
>> apply the "Easier to Ask Permission Forgiveness" style, discussed in
>> the Python Cookbook: ,
>>
>>
> Err..."Easier to Ask Forgiveness than Permission" approach is what I
> meant (perhaps proving my point about not fully understanding the
> technique!)
>
>
I certainly understand the concept and use it often. But the main time
to use it is when it can avoid interrupting the normal flow for normal
operation. For example, if you define a function that doesn't return
unless it has a valid result (for invalid, it raises an exception), then
the calling function doesn't need to explicitly check the result. That
might permit one to embed the first function call into a more complex
expression without having to decompose it to test for errors at various
points.
If the first function were written that way (raise, rather than
returning None), then we could change from:
def add_name(self):
name = result_of_SPECIALIZED_SQLcall_for_child()
try:
name + ''
self.name =ame
except TypeError:
#default to the superclass's add_name method
super(Child, self).add_name()
to:
def add_name(self):
try:
self.name = result_of_SPECIALIZED_SQLcall_for_child()
except SpecialSQLError:
#default to the superclass's add_name method
super(Child, self).add_name()
still not really worth it, but it's getting there. And notice it's
shorter, and especially so in the normal path.
DaveA