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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Multi-parameter FreeAndNil plus InitialiseNil methods – interesting code ceremony reduction by David Heffernan

Posted by jpluimers on 2020/03/05

I’m probably getting a truckload of anti-FreeAndNil folks over me, but there are cases this comes in useful, so having an overloaded version cutting down code ceremony makes sense: [WayBack] interface – Avoiding nested try…finally blocks in Delphi – Stack Overflow

Which means I need to update my type safe FreeAndNil one day.

This should be relatively straightforward, given that David published a python generator for his Delphi code [WayBack].

–jeroen

Via: [WayBack] Interesting approach by David Heffernan (*1) to the nested try..finally blocks because of multiple object creations: Overloaded InitializeNil and FreeA… – Thomas Mueller (dummzeuch) – Google+

unit ObjectHelperUnit;
interface
type
TObjectHelper = record
class function Cast<T: class>(const aValue: TObject): T; static;
class procedure FreeAndNil<T: class>(var Value: T); static;
end;
implementation
uses
System.SysConst,
System.SysUtils;
class function TObjectHelper.Cast<T>(const aValue: TObject): T;
var
lException: Exception;
begin
if Assigned(aValue) then
begin
if aValue is T then
Result := T(aValue)
else
begin
lException := EInvalidCast.CreateFmt('%s; actual type %s but expected %s.',
[SInvalidCast, aValue.QualifiedClassName, T.QualifiedClassName]);
raise lException;
end;
end
else
Result := nil;
end;
class procedure TObjectHelper.FreeAndNil<T>(var Value: T);
begin
System.SysUtils.FreeAndNil(Value);
end;
end.

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