1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
| unit MethodAddress1;
(*
This sample shows how to call a funciton by name. We use MethodAddress to
retrive the name of a function, then we call it.
Since the method belongs to a class, we need to pass the class as a prameter,
too.
In gerneral, a function - declared in a class, that is defined as
procedure TFoo.foo(i : integer);
is called as
procedure TFoo.foo(obj : TObject; i : integer);
Normally, Delphi (as well as C++) automatically add the object parameter. Now
that we get a pointer to a function from MethodAddress, that does not belong to
any class, we need to pass the parameter by hand
(C) Thomas Quester
tquester@joice.net
http://arabella.joice.net
*)
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls;
type
TTest = class
public
Calls : integer;
published
Procedure Foo;
Procedure Test;
Procedure Bar;
procedure TestI(i : integer);
procedure TestS(s : string);
function Fak(i : integer) : integer;
end;
// For every combination of parameters, we define a prototype
TFunctionCall = procedure(obj : TObject);
TFunctionICall = procedure(obj : TObject; i : integer);
TFunctionSCall = procedure(obj : TObject; s : string);
TFunctionIICall = function (obj : TObject; i : integer) : integer;
TForm1 = class(TForm)
Label1: TLabel;
ComboBox1: TComboBox;
Button1: TButton;
Label2: TLabel;
Label3: TLabel;
EditPar: TEdit;
EditResult: TEdit;
procedure Button1Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
FTest:TTest;
{ Private-Deklarationen }
public
{ Public-Deklarationen }
end;
var
Form1: TForm1;
implementation
{$R *.DFM}
procedure TForm1.Button1Click(Sender: TObject);
var p : pointer;
ptr : TFunctionCall; // Without parametes
ptrI : TFunctionICall; // (i : integer);
ptrS : TFunctionSCall; // (s : string);
ptrII : TFunctionIICall; // (i : integer) : integer
s : string;
begin
s := combobox1.text;
p := FTest.MethodAddress(s); // Get the pointer
if p <> NIL then begin
ptr := p; // Assign it to every protorype
ptri := p;
ptrii := p;
ptrs := p;
s := Lowercase(s); // Now, we decide, what prototype to use.
if (s = 'foo') or (s = 'bar') or (s = 'test')
then ptr(FTest);
if (s = 'testi') then ptri(FTest,strtoint(editPar.text));
if (s = 'tests') then ptrs(Ftest,EditPar.text);
if (s = 'fak') then editResult.text := inttostr(ptrii(ftest,strtoint(editPar.text)));
end else
MessageBox(0,'Function not defined','',MB_OK);
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
FTest := TTest.Create;
FTest.Calls := 0;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
FTest.Free;
end;
// ------------------------------------------------------------------------
// procedure TTest Foo
// Created : Quester 09.06.99 11:04:57
// ------------------------------------------------------------------------
Procedure TTest.Foo;
begin
messagebox(0,'foo',pchar(format('%d calls',[calls])),MB_OK);
inc(calls);
end;
// ------------------------------------------------------------------------
// procedure TTest Bar
// Created : Quester 09.06.99 11:05:08
// ------------------------------------------------------------------------
Procedure TTest.Bar;
begin
messagebox(0,'Bar',pchar(format('%d calls',[calls])),MB_OK);
inc(calls);
end;
procedure TTest.TestI(i : integer);
begin
messagebox(0,pchar(format('i = %d',[i])),pchar(format('%d calls',[calls])),MB_OK);
inc(calls);
end;
procedure TTest.TestS(s : string);
begin
messagebox(0,pchar(format('s = %s',[s])),pchar(format('%d calls',[calls])),MB_OK);
inc(calls);
end;
function TTest.Fak(i : integer) : integer;
var j : integer;
begin
result := 1;
for j := 1 to i do
result := result * j;
end;
// ------------------------------------------------------------------------
// procedure TTest Test
// Created : Quester 09.06.99 11:05:15
// ------------------------------------------------------------------------
Procedure TTest.Test;
begin
messagebox(0,'Test ',pchar(format('%d calls',[calls])),MB_OK);
inc(calls);
end;
end. |
