Overloading operator IN

[domasz]

I want something like this:

Code: Pascal  [Select][+][-]

1. var hey: String;
2. begin
3.   hey := 'one';
4.   if hey in ['one', 'two'] then Exit;

I tried:

Code: Pascal  [Select][+][-]

1. operator in (A: String; const B: array of const): boolean;
2. begin
3.   Result := False;
4. end;

Not ideal solution:

Code: Pascal  [Select][+][-]

1. function Group(const Ar: array of String): TStringArray;
2. var i: Integer;
3. begin
4.   SetLength(Result, High(Ar)+1);
5.  
6.   for i:=0 to High(Ar) do Result[i] := Ar[i];
7. end;
8.  
9. operator in (A: String; B: TStringArray): Boolean;
10. var i: Integer;
11. begin
12.   for i:=0 to Length(B)-1 do
13.     if B[i] = A then Exit(True);
14.  
15.   Result := False;
16. end;  
17.  
18. if hey in Group(['one', 'two'])

How do I overload IN operator?

[cdbc]

Hi
Nah, instead you should use 'IndexStr' or 'IndexText' from 'StrUtils', in a case statement, like this:

Code: Pascal  [Select][+][-]

1. var hey: String;
2. begin
3.   hey := 'one';
4.   case IndexText(hey,['one','two','three']) of
5.     0: exit; // 'one'
6.     1: Caption:= 'Two';
7.     2: showmessage('Three');
8.   end;
9. end;
10.  
11. /// edited later ///
12. or
13.   case IndexStr(hey,Group) of
14.     0: /// your stuff
15.   ...
16.   end;
17.  

Regards Benny

[domasz]

Thanks, Benny but that looks terrible. I want something pretty

[cdbc]

Hi
No worries, but be warned: 'array of const' is a whole other can of worms to open... But Hey, it's your party man...
Regards Benny

[domasz]

Code: Pascal  [Select][+][-]

1. function Group(A: String; B: String = ''; C: String = ''; D: String = ''; E: String = ''; F: String = ''; G: String = ''; H: String = ''; I: String = ''; J: String = ''): TStringArray;
2. var ii: Integer;
3.     Ar: TStringArray;
4.     Len: Integer;
5. begin
6.   Ar := TStringArray.Create(A,B,C,D,E, F,G,H,I,J);
7.  
8.   for ii:=9 downto 1 do begin
9.     if Ar[ii] <> '' then begin
10.         Len := ii+1;
11.         break;
12.       end;
13.   end;
14.  
15.   SetLength(Result, Len);
16.  
17.   for ii:=0 to Len-1 do Result[ii] := Ar[ii];
18. end;
19.  
20. operator in (A: String; B: TStringArray): Boolean;
21. var i: Integer;
22. begin
23.   for i:=0 to Length(B)-1 do
24.     if B[i] = A then Exit(True);
25.  
26.   Result := False;
27. end;
28.  
29.  

Code: Pascal  [Select][+][-]

1.   if hey in Group('one', 'two') then

It's slow but isn't it pretty?

[egsuh]

Why not following? This works.

Code: Pascal  [Select][+][-]

1. operator in (a:string; b:array of string) : boolean;
2.  
3. implementation
4.  
5. operator in(a: string; b: array of string): boolean;
6. var
7.    c: string;
8. begin
9.    Result := false;
10.    for c in b do if a=c then Exit(true);
11. end;
12.  
13. {$R *.lfm}
14.  
15. { TForm1 }
16.  
17. procedure TForm1.Button1Click(Sender: TObject);
18. begin
19.    showmessage(booltostr('this' in TStringArray(['this', 'that']), true));
20. end;
21.  

[domasz]

Because it's a Fiat Multipla to my Porsche