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Subject: Re: [boost] [General] Always treat std::strings as UTF-8
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2011-01-21 09:01:10

Alexander Lamaison wrote:
> Rule 35 of C++ Coding Standard by Sutter and Alexandrescu:
> "Avoid inheriting from classes that were not designed to be
> classes"

> "Using a standalone class as a base is a serious design error"
> The reasons given include undefined behaviour when deleting a
> std::string* pointing to an instance of the subclass, slicing
> if extra data is added and pointlessness as the subclass
> doesn't get any more access to the superclass's implementation
> that it would have had if it just kept std::string as a
> member.

If there are no additional members, then slicing and failure to invoke the derivate's destructor cause no problems, while inheritance means the base class interface needn't be duplicated. In this case, one gets a new type name that behaves just like std::string at the cost of some forwarding constructors and assignment operators (for the right return type).

That said, following Rule 35 is generally wise.

Rob Stewart robert.stewart_at_[hidden]
Software Engineer, Core Software using std::disclaimer;
Susquehanna International Group, LLP

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