Rule 10-3-3　Re-declaring pure function

[nishiyama]

Hi.

Rules 10-3-3 Rationale has the following description.

Re-declaring a function as pure may not meet developer expectations.

What do the developers expect?
What does it mean that it does not meet the expectations of developers?

[dg1980]

Hi,

for the example provided by this rule it means:

Code:

A a;// compile-time error: A is abstract
B b;// ok
C c;// compile-time error: C is abstract again

The last line is the one which does not meet common developer expectations when looking at the class hierarchy.

[misra cpp]

Our belief is that the developer expectation is that deriving a class adds behaviour to the base, not removes it.