# The SummaryInfoVisitorBase Class

Defined in: `Keyview_SummaryInformation.hpp`

The `SummaryInfoVisitorBase` class is an abstract base class that operates with the `SummaryInfoItem::`apply_visitor function. You use the `SummaryInfoVisitorBase` class by defining a class that inherits from it, implementing the required pure virtual member functions to handle each of the possible summary information types. You then call apply_visitor with an instance of your new class. The apply_visitor function ensures that the correct member function of your visitor is classed with the summary information item in its original type.

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