On Monday, March 7, 2016 at 5:49:48 PM UTC+8, Peter Otten wrote:
> ZhangXiang wrote:
>
> > In python3, when I write code like this:
> >
> > try:
> > fields = [getattr(Product, field) for field in fields.split(',')]
> > except AttributeError as e:
> > raise HTTPError(...)
> >
> > I want to raise a new type of error giving a string telling the user which
> > attribute is not valid. But I don't see any method I can use to get the
> > attribute name except inspecting e.args[0].
> >
> > Could anyone give me a hint? Maybe I miss something.
> >
> > By the way, I don't quite want to change my code to a for-loop so I can
> > access the field variable in exception handling.
>
> It seems that the name of the attribute is not made available. You have to
> parse the error message or provide the name yourself:
>
> >>> def mygetattr(object, name):
> ... try:
> ... return getattr(object, name)
> ... except AttributeError as err:
> ... err.name = name
> ... raise
> ...
> >>> class Product:
> ... foo = 42
> ...
> >>> fields = "foo,bar"
> >>> try:
> ... fields = [mygetattr(Product, field) for field in fields.split(",")]
> ... except AttributeError as err:
> ... print(err)
> ... print("Missing attribute:", err.name)
> ...
> type object 'Product' has no attribute 'bar'
> Missing attribute: bar
>
> Raising a subclass instead of mutating and reraising the original
> AttributeError is probably cleaner...
Yes. It is a way to achieving that. But is it reasonable to add an attribute to
AttributeError so we can easily get the attribute name?
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