A preliminary examination of Rtti in Delpi

The reflection mechanism in Java allows us to get information about the runtime class during run time, so is there such a feature in Delphi? The answer is that the mechanism to implement this function in Delphi is called Rtti, the nonsense is less, first to a demo:

1. First define a demo class, note that this class must be tpersistent as the base class, the code is as follows:

Delphi Code

2. Unit Unit2;
6. Interface
8. {Tdemo}
12. Uses Classes;
16. Type
20. Tdemo = Class (Tpersistent)
22. Private
26. Protected
30. Public
32. fname:string;
34. Fage:integer;
36. Constructor Create;
38. destructor Destroy; Override
40. Published
42. Property name:string read FName write FName;
44. Property Age:integer read Fage write Fage;
46. End
50. Implementation
54. {Tdemo}
58. Constructor Tdemo.create;
60. Begin
62. FName: = ' Peirenlei ';
64. End
68. destructor Tdemo.destroy;
70. Begin
74. inherited;
76. End
80. End.

2. Next, create an instance of this class:

Delphi Code

1. Ademo: = tdemo.create;
3. Ademo.name: = ' Peirenlei ';
4. Ademo.age: = 0;

3. Get the list of properties for this instance:

Delphi Code

2. Var
4. Aproplist:pproplist;
6. Atypeinfo:ptypeinfo;
8. Aclasdateinfo:ptypedata;
10. I:integer;
12. Begin
14. Atypeinfo: = Ademo.classinfo;
16. Aclasdateinfo: = Gettypedata (Atypeinfo);
18. If Aclasdateinfo.propcount <> 0 Then
20. Begin
22. Allocate space
24. Getmem (aproplist,sizeof (ppropinfo) *aclasdateinfo.propcount);
26. Try
28. Getpropinfos (ademo.classinfo,aproplist); Get a list of properties for a class
30. For I: = 0 to Aclasdateinfo.propcount- 1 do
32. Begin
34. If aproplist[i]^. proptype^. Kind <> Tkmethod Then
36. Mmo. Lines.add (Format ('%s:%s ', [aproplist[i]^. name,aproplist[i]^. proptype^.          Name]));
38. End
42. Finally
44. Freemem (aproplist,sizeof (aproplist) *aclasdateinfo.propcount);
46. End
48. End
50. End

Output:

Delphi Code

1. Name:string
2. Age:integer

3. Get a list of methods for the class:

Delphi Code

2. Var
4. Aproplist:pproplist;
6. Atypeinfo:ptypeinfo;
8. Aclasdateinfo:ptypedata;
10. I, Numpro:integer;
12. Begin
14. Atypeinfo: = Ademo.classinfo;
16. Aclasdateinfo: = Gettypedata (Atypeinfo);
18. If Aclasdateinfo.propcount <> 0 Then
20. Begin
22. Allocate space
24. Getmem (aproplist,sizeof (ppropinfo) *aclasdateinfo.propcount);
28. Try
30. Numpro: = Getproplist (ademo.classinfo,[tkmethod],aproplist);
32. If Numpro <> 0 Then
34. Begin
36. Mmo.  Lines.add ('-----events-------');
38. For I: = 0 to Numpro- 1 do//Get a list of event properties
40. Begin
42. Mmo. Lines.add (Format ('%s:%s ', [aproplist[i]^. name,aproplist[i]^. proptype^.  Name]));
44. End
46. End
48. Finally
50. Freemem (aproplist,sizeof (ppropinfo) *aclasdateinfo.propcount);
52. End
54. End
56. End

4. Get the property and property values for the instance class:

Delphi Code

2. Var
4. Aproperinfo:ppropinfo;
6. avalue:string;
8. Begin
10. Avalue: = GetPropValue (Ademo,' Name ');
12. Mmo.  Lines.add (' name= ' +avalue);
16. Avalue: = GetPropValue (Ademo,' age ');
18. Mmo.  Lines.add (' age= ' +avalue);
22. Setpropvalue (Ademo,' Name ',' zengzhen ');
24. Setpropvalue (Ademo,' age ',100);
26. Avalue: = GetPropValue (Ademo,' Name ');
28. Mmo.  Lines.add (' name= ' +avalue);
32. Avalue: = GetPropValue (Ademo,' age ');
34. Mmo.  Lines.add (' age= ' +avalue);
38. End

Output:

Delphi Code

1. Name=peirenlei
2. age=0
3. Name=zengzhen
4. Age=

http://peirenlei.iteye.com/blog/378465

A preliminary examination of Rtti in Delpi