Initialize list in function parameter

[jamie]

Bear in mind, you are now using variant records which last time I checked are now 24 bytes each, they used to be like 16 at one time at one time but who is counting.

 so, if you are planning on a large collection of these items, beware.

Jamie

[PeterHu]

Thank you all again.

[PascalDragon]

Thanks.This version is easier to understand to me.I see it as if data( const array of const) is make up of 'Variant' type.

array of const is different from Variant. While both rely on the concept of variant records, array of const is based on TVarRec and does not provide operators. It's only really intended for parameter passing, while Variant has a much wider scope due to functionality like late binding and provided operator overloads.

[PeterHu]

Thanks.This version is easier to understand to me.I see it as if data( const array of const) is make up of 'Variant' type.

array of const is different from Variant. While both rely on the concept of variant records, array of const is based on TVarRec and does not provide operators. It's only really intended for parameter passing, while Variant has a much wider scope due to functionality like late binding and provided operator overloads.

Got it,thank you.

[ALLIGATOR]

Yes, code using Variants looks even neater

Code: Pascal  [Select][+][-]

1. program app;
2. {$mode objfpc}
3. //{$codepage utf8}
4. {$modeswitch advancedrecords}
5. {$h+}
6.  
7. uses gvector;
8.  
9. type
10.   TFruit = record
11.     name: String;
12.     color: Integer;
13.     class operator :=(const data: array of Variant): TFruit;
14.   end;
15.  
16. class operator TFruit.:=(const data: array of Variant): TFruit;
17. begin
18.   Result.name:=data[0];
19.   Result.color:=data[1];
20. end;
21.  
22. procedure print(s: String);
23. begin
24.   WriteLn(s);
25. end;
26.  
27. var
28.   V: Variant; // It is necessary due to a bug https://gitlab.com/freepascal.org/fpc/source/-/issues/41492
29.  
30. begin
31.   with (specialize TVector<TFruit>.Create) do
32.   begin
33.     pushback(['apple', 1]);
34.     WriteLn(items[0].name);
35.     Free;
36.   end;
37.  
38.   print('apple');
39.   ReadLn;
40. end.
41.  

[PeterHu]

Yes, code using Variants looks even neater

Code: Pascal  [Select][+][-]

1. program app;
2. {$mode objfpc}
3. //{$codepage utf8}
4. {$modeswitch advancedrecords}
5. {$h+}
6.  
7. uses gvector;
8.  
9. type
10.   TFruit = record
11.     name: String;
12.     color: Integer;
13.     class operator :=(const data: array of Variant): TFruit;
14.   end;
15.  
16. class operator TFruit.:=(const data: array of Variant): TFruit;
17. begin
18.   Result.name:=data[0];
19.   Result.color:=data[1];
20. end;
21.  
22. procedure print(s: String);
23. begin
24.   WriteLn(s);
25. end;
26.  
27. var
28.   V: Variant; // It is necessary due to a bug https://gitlab.com/freepascal.org/fpc/source/-/issues/41492
29.  
30. begin
31.   with (specialize TVector<TFruit>.Create) do
32.   begin
33.     pushback(['apple', 1]);
34.     WriteLn(items[0].name);
35.     Free;
36.   end;
37.  
38.   print('apple');
39.   ReadLn;
40. end.
41.  

This is good!  {KISS}