[IronPython] Should DBNull treat as false ?

[Davy Mitchell]

Hi there,

I *think* this may be related to the Closed issue
http://www.codeplex.com/IronPython/WorkItem/View.aspx?WorkItemId=14605

Dino stated at the time (with the last point being relevant here):
"....NET conventions say that enum's should generally have a zero value
(FxCop CA1008 :)).  Because of that we can safely define __nonzero__ on
enums and have that return true/false based upon if the value is
zero/non-zero.  Otherwise Python says all expressions otherwise defined
return true,"

So I think the behaviour is correct though slightly counter intuitive in the
case of Null.

Cheers,
Davy

On Thu, May 15, 2008 at 11:51 AM, Sakesun Roykiattisak <
sakesun at boonthavorn.com> wrote:

>
> Some disambitguity is needed here.
>
> when  eval("a == True")  is False does not implied "a" is False.
> "a" is just not equal to True.
>
> All .NET types actually consider "nonzero" which in turn will be treat as
> True in conditional expression.
>
>
>  if System.DBNull: print 'I am something'
>>>>
>>> ...
> I am something
>
>>
>>>>
>
>  if None: print "This won't show anything"
>>>>
>>> ...
>
>>
>>>>
> What I'm asking here is whether should DBNull.Value be considered as False
> in conditional expression.
>
>
>
> On Thu, 15 May 2008 15:48:37 +0700, Davy Mitchell <daftspaniel at gmail.com>
> wrote:
>
>  DBNull is a type. Appears all .Net types evaluate to False.
>> e.g.
>> from System import DBNull, Char
>> print Char==True
>> print DBNull==True
>>
>> both will print False.
>>
>> On Thu, May 15, 2008 at 9:09 AM, Sakesun Roykiattisak <
>> sakesun at boonthavorn.com> wrote:
>>
>>
>>> Should DBNull treat as False ?
>>>
>>> Just a thought.
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>>
>>
>>
>
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-- 
Davy Mitchell
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