Introduce TKey::ReadObject<typeName>. This is a user friendly wrapper around ReadObjectAny.

README/ReleaseNotes/v612/index.md

@@ -65,6 +65,14 @@ In extremely rare cases, this change breaks a valid use where the temporary `TSt
 object before the destruction of the temporary: `TString str = objStr->GetString().ReplaceAll("a", "b");`. In these rare cases,
 please use the new function `CopyString()` which clearly indicates that it involves a temporary.
 
+## I/O Libraries
+
+- Introduce TKey::ReadObject<typeName>.  This is a user friendly wrapper around ReadObjectAny.  For example
+```{.cpp}
+auto h1 = key->ReadObject<TH1>
+```
+after which h1 will either be null if the key contains something that is not a TH1 (or derived class)
+or will be set to the address of the histogram read from the file.
 
 ## Histogram Libraries
 
@@ -94,9 +102,6 @@ please use the new function `CopyString()` which clearly indicates that it invol
 ## Geometry Libraries
 
 
-## I/O Libraries
-
-
 ## Database Libraries
 
 

io/io/inc/TKey.h

@@ -15,8 +15,8 @@
 #include "TNamed.h"
 #include "TDatime.h"
 #include "TBuffer.h"
+#include "TClass.h"
 
-class TClass;
 class TBrowser;
 class TDirectory;
 class TFile;
@@ -93,6 +93,12 @@ protected:
    virtual Int_t       Read(TObject *obj);
    virtual TObject    *ReadObj();
    virtual TObject    *ReadObjWithBuffer(char *bufferRead);
+   /// To read an object (non deriving from TObject) from the file.
+   /// This is more user friendly version of TKey::ReadObjectAny.
+   /// See TKey::ReadObjectAny for more details.
+   template <typename T> T *ReadObject() {
+      return reinterpret_cast<T*>(ReadObjectAny(TClass::GetClass(typeid(T))));
+   }
    virtual void       *ReadObjectAny(const TClass *expectedClass);
    virtual void        ReadBuffer(char *&buffer);
            void        ReadKeyBuffer(char *&buffer);