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Can't use ArrayBuffer ++ List
Sun, 2009-02-01, 14:07
If I write this:
val list = List("a")
val buf1 = new ArrayBuffer[String]
val buf2 = arraybuf ++ list
I get a compiler error on the last line:
error: erroneous reference to overloaded definition,
most specific definition is: method ++ in trait Buffer of type
(Iterable[String])scala.collection.mutable.Buffer[String],
yet alternative definition method ++ in class ArrayBuffer of type [B >:
String](Iterable[B])scala.collection.mutable.ArrayBuffer[B]
is defined in a subclass
What I really want to do is create an ArrayBuffer initialized to the
contents of a list:
val buf3 = new ArrayBuffer ++ list
but that fails for the same reason. Is there any other way to write an
expression whose result is an initialized ArrayBuffer?
I am currently on Scala 2.7.2 final.
Sun, 2009-02-01, 17:07
#2
Re: Can't use ArrayBuffer ++ List
On Sun, Feb 1, 2009 at 3:03 PM, Paul Phillips wrote:
> On Sun, Feb 01, 2009 at 05:07:24AM -0800, mtopol wrote:
>> If I write this:
>>
>> val list = List("a")
>> val buf1 = new ArrayBuffer[String]
>> val buf2 = arraybuf ++ list
>>
>> What I really want to do is create an ArrayBuffer initialized to the
>> contents of a list:
>>
>> val buf3 = new ArrayBuffer ++ list
>
I think it's a design glitch in the current libraries. I'll take care
it will be fixed in 2.8. For the moment, use ++=, as Paul suggests.
Cheers
On Sun, Feb 01, 2009 at 05:07:24AM -0800, mtopol wrote:
> If I write this:
>
> val list = List("a")
> val buf1 = new ArrayBuffer[String]
> val buf2 = arraybuf ++ list
>
> What I really want to do is create an ArrayBuffer initialized to the
> contents of a list:
>
> val buf3 = new ArrayBuffer ++ list
ArrayBuffer is mutable:
scala> val buf = new ArrayBuffer[String]
buf: scala.collection.mutable.ArrayBuffer[String] = ArrayBuffer()
scala> buf ++= List("a", "b")
scala> buf
res3: scala.collection.mutable.ArrayBuffer[String] = ArrayBuffer(a, b)