[SOLVED] Work with array property

[Okoba]

Hello,
In this sample can you tell me how can I correctly get length of the array, and add or delete elements to it? I can cast it to Integer array but I like to know the generic way that works for all element types.

Code: Pascal  [Select][+][-]

1. program Project1;
2. {$mode objfpc}{$H+}
3. {$M+}
4. {$RTTI EXPLICIT
5.    PROPERTIES([vcPrivate,vcProtected,vcPublic,vcPublished])
6.    FIELDS([vcPrivate,vcProtected,vcPublic,vcPublished])
7.    METHODS([vcPrivate,vcProtected,vcPublic,vcPublished])}
8. uses
9.   TypInfo;
10.  
11. type
12.   TTest = record
13.     A: array of integer;
14.   end;
15. var
16.   T: TTest;
17.   FieldTable: PExtendedFieldInfoTable;
18.   FieldCount, I: Integer;
19. begin
20.   T.A := [1, 2, 3];
21.   FieldCount := GetFieldList(TypeInfo(TTest), FieldTable);
22.   for I := 0 to FieldCount - 1 do
23.     with FieldTable^[I]^ do
24.     begin
25.       if Name^ = 'A' then
26.       begin
27.       How to get the array length?
28.       How to add another item to the array?
29.       end;
30.     end;
31.   ReadLn;
32. end.
33.  

[ALLIGATOR]

It's scary, but it works

Code: Pascal  [Select][+][-]

1. program Project1;
2. {$mode objfpc}{$H+}
3. {$M+}
4. {$RTTI EXPLICIT
5.    PROPERTIES([vcPrivate,vcProtected,vcPublic,vcPublished])
6.    FIELDS([vcPrivate,vcProtected,vcPublic,vcPublished])
7.    METHODS([vcPrivate,vcProtected,vcPublic,vcPublished])}
8. uses
9.   TypInfo;
10.  
11. type
12.   TTest = record
13.     A: array of UInt64;
14.   end;
15. var
16.   T: TTest;
17.   FieldTable: PExtendedFieldInfoTable;
18.   FieldCount, I: Integer;
19.   newlen: SizeInt = 33;
20. begin
21.   T.A := [1, 2, 3];
22.   FieldCount := GetFieldList(TypeInfo(TTest), FieldTable);
23.   for I := 0 to FieldCount - 1 do
24.     if FieldTable^[I]^.Name^ = 'A' then
25.     begin
26.       //How to get the array length?
27.       WriteLn(DynArrayBounds(@PByte(@T)[FieldTable^[I]^.FieldOffset], FieldTable^[I]^.FieldType^)[0]+1);
28.  
29.       //How to add another item to the array?
30.       DynArraySetLength(PPointer(@PByte(@T)[FieldTable^[I]^.FieldOffset])^, FieldTable^[I]^.FieldType^, 1, @newlen);
31.     end;
32.  
33.   WriteLn(Length(T.A));
34.   ReadLn;
35. end.

[Okoba]

Thank you!

Code: Pascal  [Select][+][-]

1. PPointer(@PByte(@T)[FieldTable^[I]^.FieldOffset])^

This part is confusing? it is pointer of the array property?
How can i set the newly added element dynamically depending on the array element type? like if it is integer set it to 1 and if string set to '1'?

[ALLIGATOR]

Something like that, but I'm starting to dislike this code more and more

Besides, I'm still confused as to why I get the array element type this way. I originally wrote it differently, but it didn't work...

And this worked, but I don't have time to figure it out yet, so I'll leave it as is

Code: Pascal  [Select][+][-]

1. program Project1;
2. {$mode objfpc}{$H+}
3. {$M+}
4. {$RTTI EXPLICIT
5.    PROPERTIES([vcPrivate,vcProtected,vcPublic,vcPublished])
6.    FIELDS([vcPrivate,vcProtected,vcPublic,vcPublished])
7.    METHODS([vcPrivate,vcProtected,vcPublic,vcPublished])}
8. uses
9.   TypInfo;
10.  
11. type
12.   TTest = record
13.     A: array of Integer;
14.   end;
15. var
16.   T: TTest;
17.   FieldTable: PExtendedFieldInfoTable;
18.   FieldCount, I: Integer;
19.   newlen: SizeInt = 33;
20.   s: string;
21.   ptd: PTypeData;
22. begin
23.   T.A := [1, 2, 3];
24.   FieldCount := GetFieldList(TypeInfo(TTest), FieldTable);
25.   for I := 0 to FieldCount - 1 do
26.     if FieldTable^[I]^.Name^ = 'A' then
27.     begin
28.       //How to get the array length?
29.       WriteLn(DynArrayBounds(@PByte(@T)[FieldTable^[I]^.FieldOffset], FieldTable^[I]^.FieldType^)[0]+1);
30.  
31.       //How to add another item to the array?
32.       DynArraySetLength(PPointer(@PByte(@T)[FieldTable^[I]^.FieldOffset])^, FieldTable^[I]^.FieldType^, 1, @newlen);
33.  
34.       WriteStr(s, FieldTable^[I]^.FieldType^^.Kind);
35.       WriteLn(s);
36.  
37.       case FieldTable^[I]^.FieldType^^.Kind of
38.         tkUnknown:;
39.         tkInteger:;
40.         tkChar:;
41.         tkEnumeration:;
42.         tkFloat:;
43.         tkSet:;
44.         tkMethod:;
45.         tkSString:;
46.         tkLString:;
47.         tkAString:;
48.         tkWString:;
49.         tkVariant:;
50.         tkArray:;
51.         tkRecord:;
52.         tkInterface:;
53.         tkClass:;
54.         tkObject:;
55.         tkWChar:;
56.         tkBool:;
57.         tkInt64:;
58.         tkQWord:;
59.         tkDynArray:
60.         begin
61.           ptd:=GetTypeData(FieldTable^[I]^.FieldType^);
62.  
63.           case ptd^.OrdType of
64.             otSLong: PInteger(PPointer(@PByte(@T)[FieldTable^[I]^.FieldOffset])^)[3]:=44;
65.           end;
66.  
67.         end;
68.         tkInterfaceRaw:;
69.         tkProcVar:;
70.         tkUString:;
71.         tkUChar:;
72.         tkHelper:;
73.         tkFile:;
74.         tkClassRef:;
75.         tkPointer:;
76.       end;
77.  
78.     end;
79.  
80.   WriteLn(Length(T.A));
81.   WriteLn(T.A[0]);
82.   WriteLn(T.A[1]);
83.   WriteLn(T.A[2]);
84.   WriteLn(T.A[3]);
85.   WriteLn(T.A[4]);
86.   ReadLn;
87. end.

[PascalDragon]

Code: Pascal  [Select][+][-]

1. PPointer(@PByte(@T)[FieldTable^[I]^.FieldOffset])^

This part is confusing? it is pointer of the array property?

It's a field, not a property.