knowing/Knowing — Issue #29: Rework TFilter
Author: muuki88
Created: 2012-02-06 21:17:18+00:00
State: open
Labels: core, enhancement

### Current status

All implemented filter classes override the `filter(instances: Instances): Instances`
method, because for performance or implementation reasons.

### Possible solution

The performance issues is raised as the `query` method must create
a new _Instances_ object each time it's called.

```scala

def query(Instance query, Instances output)

def outputFormat(Instances input): Instances

```

This spoils the code with two more methods.