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+
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| 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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