| Description |
The SetRange method takes elements from SourceCollection and overlays copies of them onto elements of the current ArrayList, starting at TargetIndex.
Just like CopyTo, SetRange performs a shallow copy. When the SourceCollection holds reference (non primitive) data types, the target array element values still refer to the same objects that current array elements refer to. This is what is referred to as a shallow copy. A deep copy would create new versions of the referred objects.
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| Microsoft MSDN Links |
System.Collections
System.Collections.ArrayList
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| Overlaying a 4 element ArrayList onto a 10 element ArrayList |
program Project1;
{$APPTYPE CONSOLE}
uses
System.Collections;
var
Source, Target : System.Collections.ArrayList;
i : Integer;
begin
// Create our array list objects
Source := ArrayList.Create;
Target := ArrayList.Create;
// Fill them
Source.Add('Source.Zero');
Source.Add('Source.One');
Source.Add('Source.Two');
Source.Add('Source.Three');
Target.Add('Target.Zero');
Target.Add('Target.One');
Target.Add('Target.Two');
Target.Add('Target.Three');
Target.Add('Target.Four');
Target.Add('Target.Five');
Target.Add('Target.Six');
Target.Add('Target.Seven');
Target.Add('Target.Eight');
Target.Add('Target.Nine');
// Copy the middle 4 elements to the target array
Console.WriteLine('Copying the Source to the middle of the target array :');
Console.WriteLine;
Target.SetRange(3, Source);
// Display the target array contents
for i := 0 to Target.Count-1 do
Console.WriteLine(Target.Item[i].ToString);
Console.Readline;
end.
| | Show full unit code | Copying the Source to the middle of the target array :
Target.Zero
Target.One
Target.Two
Source.Zero
Source.One
Source.Two
Source.Three
Target.Seven
Target.Eight
Target.Nine
| | | Illustrating the shallowness of the SetRange element copy | program Project1;
{$APPTYPE CONSOLE}
uses
System.Collections;
type
MyClass = Class
private
mcName : String;
published
Property Name : String
read mcName
write mcName;
Constructor Create(Name : String); overload;
Function ToString : String; overload;
end;
// MyClass methods
constructor MyClass.Create(Name : String);
begin
inherited Create;
mcName := Name;
end;
function MyClass.ToString : String;
begin
Result := Name;
end;
// Main code
var
Source, Target : System.Collections.ArrayList;
MyObject : MyClass;
i : Integer;
begin
// Create our array list objects
Source := ArrayList.Create;
Target := ArrayList.Create;
// Fill them
Source.Add(MyClass.Create('Source.Zero'));
Source.Add(MyClass.Create('Source.One'));
Source.Add(MyClass.Create('Source.Two'));
Source.Add(MyClass.Create('Source.Three'));
Target.Add(MyClass.Create('Target.Zero'));
Target.Add(MyClass.Create('Target.One'));
Target.Add(MyClass.Create('Target.Two'));
Target.Add(MyClass.Create('Target.Three'));
Target.Add(MyClass.Create('Target.Four'));
Target.Add(MyClass.Create('Target.Five'));
Target.Add(MyClass.Create('Target.Six'));
Target.Add(MyClass.Create('Target.Seven'));
Target.Add(MyClass.Create('Target.Eight'));
Target.Add(MyClass.Create('Target.Nine'));
// Copy the middle 4 elements to the target array
Console.WriteLine('Copying the Source to the middle of the target array :');
Console.WriteLine;
Target.SetRange(3, Source);
// Display the target array contents
for i := 0 to Target.Count-1 do
begin
MyObject := MyClass(Target.Item[i]);
Console.WriteLine(MyObject.ToString);
end;
// Update element 1 of the source array
Console.WriteLine;
Console.WriteLine('Updating element 2 of the source only');
Console.WriteLine;
MyObject := MyClass(Source[2]);
MyObject.Name := 'Source.Two modified';
// Display the target array contents
for i := 0 to Target.Count-1 do
begin
MyObject := MyClass(Target.Item[i]);
Console.WriteLine(MyObject.ToString);
end;
Console.Readline;
end.
| | Show full unit code | Copying the Source to the middle of the target array :
Target.Zero
Target.One
Target.Two
Source.Zero
Source.One
Source.Two
Source.Three
Target.Seven
Target.Eight
Target.Nine
Updating element 2 of the source only
Target.Zero
Target.One
Target.Two
Source.Zero
Source.One
Source.Two modified
Source.Three
Target.Seven
Target.Eight
Target.Nine
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