In our previous episode, Benito van der Zander said:
> why is sizeof on object/class fields sometimes allowed and sometimes not?
>
> type TTest = object
> ? f: integer;
> ? class procedure test;
> end;
>
> class procedure TTest.test;
> begin
> ? writeln(sizeof(f));???????????? // does not compile
> ? writeln(sizeof(TTest.f));? // compiles
> end;
For custom types that don't have a predefined IComparer<> instance, afaik
you can define it yourself and set it in the TDictionary<> type.
Just search for I/Tcomparer<> in the generics.* sources.
I do have some example, but that is for the generic sort, not the
dictionary:
program gensort2;
{$APPTYPE CONSOLE}
{$R *.res}
uses
System.SysUtils,generics.collections,generics.defaults;
type
TSomeRecord = record
angle:single;
angleasstring:string;
end;
type
TSomeRecordComparer1 = class(TComparer<TSomeRecord>)
public
function Compare(const Left, Right: TSomeRecord): Integer; override;
end;
function TSomeRecordComparer1.Compare(const Left, Right: TSomeRecord):
Integer;
begin
Result := round(left.angle - right.angle);
end;
var some:array of TSomeRecord;
i : integer;
cmp : TSomeRecordComparer1;
begin
cmp:=TSomeRecordComparer1.Create;
setlength(some,6);
some[0].angle:=100; some[1].angle:=25; some[2].angle:=270;
some[3].angle:=90; some[4].angle:=15; some[5].angle:=300;
for i := 0 to length(some)-1 do
some[i].angleasstring:=FloatToStrF(some[i].angle,fffixed,8,4);
// tarray.sort<tsomerecord>(some,cmp,3,3); // partial sort
tarray.sort<tsomerecord>(some,cmp);
for i := 0 to length(some)-1 do
writeln(some[i].angle:10:5,' ',some[i].angleasstring);
readln;
end.
_______________________________________________
fpc-devel maillist - fpc-devel@lists.freepascal.org
http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
