[Gambas-user] Feature request: Giving _compare() an optional user data argument

[Tobias Boege]

On Sun, 18 May 2014, Beno?t Minisini wrote:
> Le 14/05/2014 21:38, Tobias Boege a ?crit :
> > Hi Benoit,
> >
> > when we wanted to sort a 2d array (table) by a specific column, variable at
> > runtime, we did the following:
> >
> >   1. Create the class, let's call it "Record", to represent the table
> >      records which implements a _compare() method and has a SortField
> >      property which indicates to _compare() which column we want to sort
> >      by.
> >   2. Create a class "RecordGroup" which Inherits Object[] and has a
> >      SortField(Field As Integer, Optional Mode As Integer) method which is
> >      a multicolumn-aware version of Sort:
> >
> >      Public Sub SortField(Field As Integer, Optional Mode As Integer)
> >        Dim iInd As Integer
> >
> >        For iInd = 0 To Super.Count - 1
> >          Super[iInd].SortField = Field
> >        Next
> >        Super.Sort(Mode)
> >      End
> >   3. Then, we must work with RecordGroups which we can sort by, say, column 7
> >      using myGroup.SortField(7).
> >
> > You see that we need to set each object's SortField property to the Field
> > value in order to make the _compare()s work together as we desire. If some
> > objects "don't get it", we will lose transitivity of our relation and the
> > sort may fail.
> >
> > We can't use static properties in the Record class either because we may
> > want to have multiple groups.
> 
> I don't understand that: if the sort field is a parameter of the sort, 
> then you can store it inside a static variable just during the sort.
> 

Hmm... that's an idea, indeed! Because we can ensure that no parallel sorts
mess up the static variable.

Too bad that this is a good solution. We were already excited about this
potential new feature :-)

Regards,
Tobi

-- 
"There's an old saying: Don't change anything... ever!" -- Mr. Monk