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From "Will Glass-Husain" <wgl...@forio.com>
Subject Re: POLL: null context attribute values
Date Fri, 16 Jan 2004 17:07:32 GMT
Thanks Nathan for clearing that up.  But now after Claude's email I'm
confused again.

Is there a difference between

#if ($foo == null)

and #if ($foo)  ?

The reason I ask is that many of my reference properties are database
fields, which may be null.  I check for null with:
if($record.fieldname)    field is not defined  #end
if(!$record.fieldname)    field is defined   #end

In both cases, $record is defined, but the property fieldname may or may not
be null.

Will this still be the same with the new proposal?

WILL



----- Original Message ----- 
From: "Claude Brisson" <claude@savoirweb.com>
To: "Velocity Users List" <velocity-user@jakarta.apache.org>
Sent: Friday, January 16, 2004 8:55 AM
Subject: Re: POLL: null context attribute values


> hum.... quite...
>
> #if( $foo )
>     $foo
> #elseif ($foo == false)
>      foo is false
> #else
>     foo is null
>  #end
>
> :-)
>
> CloD
>
> ----- Original Message ----- 
> From: "Nathan Bubna" <nathan@esha.com>
> To: "Velocity Users List" <velocity-user@jakarta.apache.org>
> Sent: Friday, January 16, 2004 5:47 PM
> Subject: Re: POLL: null context attribute values
>
>
> > Will Glass-Husain said:
> > > Question: Would the following syntax still work?
> > >
> > > #if($reference)
> > > $reference is defined
> > > #end
> >
> > yes.  in fact, it should work even better since:
> >
> > #foreach( $foo in $foos )
> >     #if( $foo ) $foo #else foo is null #end
> > #end
> >
> > should now work as intuition expects when $foos contains null values,
and
> >
> > #set( $foo = "bar" )
> > #set( $foo = $tool.returnNull() )
> > #if( $foo ) $foo #else foo is null #end
> >
> > should display " foo is null " instead of " bar " (as it does
currently).
> >
> > make sense now?
> >
> > Nathan Bubna
> > nathan@esha.com
> >
> >
> > Geir Magnusson Jr said:
> > > > On Jan 16, 2004, at 7:15 AM, Christoph.Reck@dlr.de wrote:
> > > >
> > > > > Geir Magnusson Jr wrote:
> > > > >> On Jan 15, 2004, at 6:38 PM, Nathan Bubna wrote:
> > > > >>> lloyd said:
> > > > >>>
> > > > >>>> Nathan Bubna wrote:
> > > > >> [snip]
> > > > >>>> ...or just make it the toggle transitional - deprecate
it for a
> > > > >>>> following release of velocity?
> > > > >>>
> > > > >>>
> > > > >>> sure, i'd suggest we could remove the toggle in the next
release
> > > > >>> where we put
> > > > >>> aside BC concerns.  2.0 or whatever.
> > > > >>>
> > > > >>>> i can't imagine why anyone would want the old (ie current)
> > > > >>>> behavior...
> > > > >>>
> > > > >>> well, then i've just barely got you beat there,
> > > > >>> because i can imagine precisely one:  backwards compatibility!
;)
> > > > >>>
> > > > >> I still wish I could recall the reason, because we had one....
:)
> > > > >
> > > > > The reason was due to the fact that a Hashtable does not accept
> nulls,
> > > > > but Velocity uses a Map. Geir wanted the original vel
implementation
> > > > > to allow backing the context by whatever the application
developers
> > > > > desire - even a Hashtable.
> > > >
> > > > Thank you!  That's amazing that you can remember that.
> > > >
> > > > >
> > > > >
> > > > > Now the proper BC proceeding should be:
> > > > >
> > > > > 1) The next relase of velocity sould have a new switch that
defaults
> to
> > > > > the old form if not explicetely set in the properties. A loud
> WARNING
> > > > > should be emitted into the logs (for whoever reads them) that
tells
> > > > > to switch it to the new mode after upgrading/verifying any
existing
> > > > > templates.
> > > > >
> > > > > 2) Then the release after that can default to the switch the
"Right
> > > > > Way" (tm)
> > > > > and emit a WARNING if the switch has not explicetely set in the
> > > > > properties.
> > > > >
> > > >
> > > > That's not a bad plan.  Different than what I thought yesterday, but
> > > > that would work.  We could do a release w/ the old way as default,
w/
> > > > new way as switch to get the map, etc out there.  Then immediately
> > > > uprev by 0.1 and have the new way as default, no other difference.
And
> > > > then
> > > >
> > > > > 3) In velocity 2.0 the switch can be dropped altogether (or an
ERROR
> > > > > can
> > > > > show if it still exits and is set to the old BC mode).
> > > > >
> > > > > For whatever these 0.02c are worth.
> > > >
> > > > In euro, not as much as it used to ...  :)
> > > >
> >
> >
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> >
>
>
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