JCL Help:ISafeGuard

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Interface used to provide automatic resource destruction.


 public ISafeGuard = interface;


ISafeGuard is the interface used by the Guard functions to provide automatic resource destruction. A safeguard is an interface which gets associated with the resource and ensures that when execution leaves the scope at which the safeguard variable is declared, the resource is released (e.g. memory freed or object destroyed). Since a safeguard is an interface and Delphi ensures that interfaces are released even when an exception is raised, you can use a safeguard to ensure that a resource always gets freed without having to explicitly code it. For example:
var SafeGuard: ISafeGuard; Strings: TStrings; begin Strings := TStrings(Guard(TStringList.Create, SafeGuard)); String.ReadFromFile('d:delphijclsourceJclBase.pas'); // code to manipulate strings goes here Strings.SaveToFile('d:delphijclsourceJclBase.pas'); end;
In the above code, the TStrings object is associated with the SafeGuard. No matter how the function terminates, the safeguard ensures that the TStrings object is destroyed. Usually you will simply store the returned safeguard interface pointer in a variable at the appropriate scope and forget about it. However, the ISafeGuard interface does provide some additional functionality which may be useful at times.

See Also

Guard GuardGetMem GuardAllocMem






Rudy Velthuis

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