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Re: unittest: assertRaises() with an instance instead of a type

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Ulrich Eckhardt wrote:

> True. Normally. I'd adapting to a legacy system though, similar to
> OSError, and that system simply emits error codes which the easiest way
> to handle is by wrapping them.

If you have

err = some_func()
if err: 
   raise MyException(err) 

the effort to convert it to

exc = lookup_exception(some_func())
if exc:
    raise exc

is small. A fancy way is to use a decorator:

#untested
def code_to_exception(table):
    def deco(f):
        def g(*args, **kw):
            err = f(*args, **kw)
            exc = table[err]
            if exc is not None: 
                raise exc
        return g
    return f

class MyError(Exception): pass
class HyperspaceBypassError(MyError): pass

@code_to_exception({42: HyperspaceBypassError, 0: None})
def some_func(...):
    # ...

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unittest: assertRaises() with an instance instead of a type Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-03-28 14:28 +0200
  Re: unittest: assertRaises() with an instance instead of a type Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-28 18:07 +0000
    Re: unittest: assertRaises() with an instance instead of a type Ben Finney <ben+python@benfinney.id.au> - 2012-03-29 12:55 +1100
      Re: unittest: assertRaises() with an instance instead of a type Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-29 06:35 +0000
      Re: unittest: assertRaises() with an instance instead of a type Peter Otten <__peter__@web.de> - 2012-03-29 08:55 +0200
      Re: unittest: assertRaises() with an instance instead of a type Steve Howell <showell30@yahoo.com> - 2012-03-28 22:50 -0700
    Re: unittest: assertRaises() with an instance instead of a type Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-03-29 09:08 +0200
      Re: unittest: assertRaises() with an instance instead of a type Peter Otten <__peter__@web.de> - 2012-03-29 09:48 +0200
      Re: unittest: assertRaises() with an instance instead of a type Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-30 02:45 +0000
        Re: unittest: assertRaises() with an instance instead of a type Ethan Furman <ethan@stoneleaf.us> - 2012-03-30 10:45 -0700
    Re: unittest: assertRaises() with an instance instead of a type Ethan Furman <ethan@stoneleaf.us> - 2012-03-29 08:35 -0700
      Re: unittest: assertRaises() with an instance instead of a type Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-30 02:53 +0000
  Re: unittest: assertRaises() with an instance instead of a type Terry Reedy <tjreedy@udel.edu> - 2012-03-28 14:26 -0400
    Re: unittest: assertRaises() with an instance instead of a type Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-03-29 09:28 +0200
      Re: unittest: assertRaises() with an instance instead of a type Terry Reedy <tjreedy@udel.edu> - 2012-03-29 11:04 -0400
    tabs/spaces (was: Re: unittest: assertRaises() with an instance instead of a type) Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-03-29 09:18 +0200
      Re: tabs/spaces (was: Re: unittest: assertRaises() with an instance instead of a type) Roy Smith <roy@panix.com> - 2012-03-29 08:49 -0400
      Re: tabs/spaces Dave Angel <d@davea.name> - 2012-03-29 11:16 -0400
      Re: tabs/spaces Terry Reedy <tjreedy@udel.edu> - 2012-03-29 11:25 -0400
        Re: tabs/spaces Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-03-30 09:05 +0200
          Re: tabs/spaces Dave Angel <d@davea.name> - 2012-03-30 08:47 -0400
            Re: tabs/spaces Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-04-02 09:12 +0200
              Re: tabs/spaces Terry Reedy <tjreedy@udel.edu> - 2012-04-02 03:42 -0400

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