[SOLVED] Sorry about Variant

[egsuh]

I don't like to use Variant type, but sometimes this is convenient type in web programming and when I use TStringList. In TStringList, I can save like

AStringList.Values['id'] := V; 

V is Variant type, but is integer value here.


Also assignments like

I := V;  // I is an integer-type variable, V is a variant type variable

works fine.

But 

ShowMessageFmt('The value is %d', [V]);

raises error. Well specifying type of variant isn't a big deal, like:

ShowMessageFmt('The value is %d', [Integer(V)]);


but shouldn't variants be interpreted as "expected" type?  It's not different from using StrToInt function, etc.

[mse]

ShowMessageFmt is defined as

Code: Pascal  [Select][+][-]

1. procedure ShowMessageFmt(const aMsg: string; Params: array of const);
2.  

-> the compiler can not know what types are expected in "Params" parameter.

[Thaddy]

Well, I see the point, since this works:

Code: Pascal  [Select][+][-]

1. var v:variant;
2. begin
3.   v:=100;
4.   writeln(v);
5. end.

Anyway, variants are a last resort and very slow.

[soerensen3]

This isn't much more complicated

Code: Pascal  [Select][+][-]

1. program Project1;
2.  
3. uses
4.   SysUtils, Classes;
5.  
6. var
7.   S: TStringList;
8.   ints: array of Integer;
9.   i: Integer;
10. begin
11.   SetLength( ints, 10 );
12.   for i:= 0 to 9 do
13.     ints[ i ]:= i;
14.   S:= TStringList.Create;
15.   for i:= low( ints ) to high( ints ) do begin
16.     S.Append( ints[ i ].ToString );
17.     WriteLn( S[ i ]);
18.   end;
19.  
20.   //---
21.   SetLength( ints, S.Count );
22.   for i:= 0 to S.Count - 1 do begin
23.     ints[ i ]:= S[ i ].ToInteger;
24.     WriteLn( ints[ i ]);
25.   end;
26. end.
27.              

However you can always do this:

Code: Pascal  [Select][+][-]

1. WriteStr( SomeString, v );

[Thaddy]

Yo. If writeln works, writestr also works...indeed.

[egsuh]

Does this mean that the type-conversion of variant is done at compilation, not at runtime?