Short Function.

Here's my implementation of function according to The Power of 10;

"Restrict functions to a single printed page."

As bonus, I didn't use global variable if possible. So if a function or procedure need a variable from others, it have to be passed using parameter on that function.

If we look at the code below, we know that it can be rewritten using a long single procedure or function. But according The Power of Ten, a function should be as short as possible so it could be printed in a single page.

So, instead one long multiple page function, I write/break it as several short-single-printed-page functions. :)

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    Button1: TButton;
    Edit3: TEdit;
    Edit4: TEdit;
    procedure proses;
    function konversi(a:real;c,d:char):string;
    function konversiC(a:real;d:char):string;
    function konversiF(a:real;d:char):string;
    function konversiR(a:real;d:char):string;
    function konversiK(a:real;d:char):string;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
  proses;
end;

procedure tform1.proses;
var
  a:real;
  s,b:string;
  c,d:char;
begin
  a:=strToFloat(edit1.Text);
  s:=edit2.Text;
  c:=s[1];
  s:=edit4.Text;
  d:=s[1];
  b:=konversi(a,c,d);
  edit3.Text:=b;
end;

function tform1.konversi(a:real;c,d:char):string;
begin
  case c of
    'C':konversi:=konversiC(a,d);
    'F':konversi:=konversiF(a,d)
    'R':konversi:=konversiR(a,d)
    'K':konversi:=konversiK(a,d)
    else konversi:='error';
  end;
end;

function tform1.konversiC(a:real;d:char):string;
begin
  case d of
    'C':konversiC:=floatToStr(a);
    'F':konversiC:=floatToStr(a*9/5+32);
    'R':konversiC:=floatToStr(a*4/5);
    'K':konversiC:=floatToStr(a+273);
    else konversiC:='Error';
  end;
end;

function tform1.konversiF(a:real;d:char):string;
begin
  case d of
    'C':konversiF:=floatToStr((a-32)*5/9);
    'F':konversiF:=floatToStr(a);
    'R':konversiF:=floatToStr((a-32)*4/9);
    'K':konversiF:=floatToStr((a-32)*5/9+273);
    else konversiF:='Error';
  end;
end;

function tform1.konversiR(a:real;d:char):string;
begin
  case d of
    'C':konversiR:=floatToStr(a*5/4);
    'F':konversiR:=floatToStr(a*9/4+32);
    'R':konversiR:=floatToStr(a);
    'K':konversiR:=floatToStr(a*5/4+273);
    else konversiR:='Error';
  end;
end;

function tform1.konversiK(a:real;d:char):string;
begin
  case d of
    'C':konversiK:=floatToStr(a-273);
    'F':konversiK:=floatToStr((a-273)*9/5+32);
    'R':konversiK:=floatToStr((a-273)*4/5);
    'K':konversiK:=floatToStr(a);
    else konversiK:='Error';
  end;
end;

end.

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