Bug in Scala XMLs Attribute remove?

Hiya,

use:

import scala.xml._

val x =

println("x " + x)

val y = x.copy(attributes = x.attributes.remove("a"))

println("y " + y)

instead, the individual Attributes know about their next in the chain
but not their previous so calling remove on an Attribute won't do as
you expect.

If you are calling code similar to val y = x.copy ... above and its
still not working, it'd look very much like a bug.

Cheers,
Chris

On Mon, Jan 2, 2012 at 2:04 PM, Silvio wrote:
> I can not find any documentation that states what the remove method
> (either variant) on MetaData and its subclass Attribute are supposed
> to do. I suspected it is supposed to return the complete attribute
> list except the specified key.
>
> But to my surprise method remove(namespace,scope,key) on Attribute
> does not do that (Scala IDE 2.1.0 nightly). Instead it just returns
> the remainder of the attributes FOLLOWING the specified key. Since it
> is impossible to predict where in the chain a key might be (which is a
> nuisance on its own) it is unlikely that this is the intended
> behaviour. Is it simply a bug or am I completely misinterpreting
> things?

Hello Chris,

x.attributes.remove IS the remove I am talking about. In the XML
library there is no distinction between all attributes and an
individual one. x.attributes simply returns the first attribute that
indeed knows only about the next values and not the previous ones.

BTW: only the one with the namespace is wriong, the one you quote here
with only the key is working fine. I looked into the code: the latter
correctly uses copy on its recursive call while the namespace version
does not. I am quite sure now it is a bug.

Cheers,

Silvio

On Jan 2, 5:25 pm, Chris Twiner wrote:
> Hiya,
>
> use:
>
> import scala.xml._
>
> val x =
>
> println("x " + x)
>
> val y = x.copy(attributes = x.attributes.remove("a"))
>
> println("y " + y)
>
> instead, the individual Attributes know about their next in the chain
> but not their previous so calling remove on an Attribute won't do as
> you expect.
>
> If you are calling code similar to val y = x.copy ... above and its
> still not working, it'd look very much like a bug.
>
> Cheers,
> Chris
>
>
>
> > things?

lol, I'm really not doing well at communicating today, with just the
result of find, for example, it won't work, you need the elements head
attribute to work with:

// I meant more like - and no you didn't just see me use .get :

val z = x.copy( attributes = x.attributes.find(_.key == "a").get.remove("a"))

The attributes hierarchy is one of the motivators for Scales, and
Anti-Xml too I'd guess.

But yeah it very much looks like a bug for ns lookups :<

On Mon, Jan 2, 2012 at 6:05 PM, Silvio wrote:
> Hello Chris,
>
> x.attributes.remove IS the remove I am talking about. In the XML
> library there is no distinction between all attributes and an
> individual one. x.attributes simply returns the first attribute that
> indeed knows only about the next values and not the previous ones.
>
> BTW: only the one with the namespace is wriong, the one you quote here
> with only the key is working fine. I looked into the code: the latter
> correctly uses copy on its recursive call while the namespace version
> does not. I am quite sure now it is a bug.
>
> Cheers,
>
> Silvio
>
>
> On Jan 2, 5:25 pm, Chris Twiner wrote:
>> Hiya,
>>
>> use:
>>
>> import scala.xml._
>>
>> val x =
>>
>> println("x " + x)
>>
>> val y = x.copy(attributes = x.attributes.remove("a"))
>>
>> println("y " + y)
>>
>> instead, the individual Attributes know about their next in the chain
>> but not their previous so calling remove on an Attribute won't do as
>> you expect.
>>
>> If you are calling code similar to val y = x.copy ... above and its
>> still not working, it'd look very much like a bug.
>>
>> Cheers,
>> Chris
>>
>>
>>
>> > things?