I generally agree that DBNull should be false - it is logically the same as None. We can define __nonzero__ on DBNull.Value to make this work. I've opened bug #16695 to track the issue (http://www.codeplex.com/IronPython/WorkItem/View.aspx?WorkItemId=16695) and it should be an easy fix.
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dan Eloff Sent: Monday, May 19, 2008 9:36 PM To: Discussion of IronPython Subject: Re: [IronPython] Should DBNull treat as false ? I don't think DBNull.Value should be True, it's purpose is very similar to None, and it should have the same truth value. Doing otherwise complicates conditional expressions and leads to conversations like this on the mailing list... Usually it's best to choose the path of least surprise. -Dan On Thu, May 15, 2008 at 1:41 PM, Davy Mitchell <[EMAIL PROTECTED]> wrote: > 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 > <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> >> 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 < >>> [EMAIL PROTECTED]> wrote: >>> >>>> >>>> Should DBNull treat as False ? >>>> >>>> Just a thought. >>>> _______________________________________________ >>>> Users mailing list >>>> [email protected] >>>> http://lists.ironpython.com/listinfo.cgi/users-ironpython.com >>>> >>> >>> >>> >> >> >> _______________________________________________ >> Users mailing list >> [email protected] >> http://lists.ironpython.com/listinfo.cgi/users-ironpython.com > > > > -- > Davy Mitchell > Blog - http://www.latedecember.co.uk/sites/personal/davy/ > Twitter - http://twitter.com/daftspaniel > Skype - daftspaniel http://needgod.com > _______________________________________________ > Users mailing list > [email protected] > http://lists.ironpython.com/listinfo.cgi/users-ironpython.com > > _______________________________________________ Users mailing list [email protected] http://lists.ironpython.com/listinfo.cgi/users-ironpython.com _______________________________________________ Users mailing list [email protected] http://lists.ironpython.com/listinfo.cgi/users-ironpython.com
