Monday, March 17, 2008

virtual -- only 1 of the big 3 please

In practice, people seldom virtualize these by mistake, but i feel it's good to know why.

ctr (incl copier) are never virtual-- object is incomplete during construction.

assignment can be (uselessly) marked virtual but won't work as virtual. Virtual is strict on params. All overrides must specify identical params as the "root" version [1].

There's always a (default or custom) op= with a param "const HostClass&", so this func signature is as unique as a fingerprint -- Will never match the root version.

Among the big 3, only dtor should be virtual.

[1] both c++ and java. [[annotated ref manual]] explains why.

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