Re: simple class

From: (Stefan Ram)
12 May 2014 22:16:39 GMT
Dombo <dombo@disposable.invalid> writes:

Op 11-May-14 20:18, Stefan Ram schreef:

Paavo Helde <> writes:

Err, no. If the ultimate goal is to keep interfaces fixed, then
getBalance() would still return double for back-compatibility (and marked
deprecated in the documentation and/or by the relevant compiler-specific
extensions) and there would be a new function getBalanceEx() returning a
fixed decimal.

But the effect is the same: all clients that want to benefit
from the new implementation have to be changed. I used to
believe that the promise of encapsulation was that the
implementation can be changed without the clients having to
be changed.

Encapsulation won't help in case the interface itself is broken, like in
this example. And since the interface is broken, so are the client using
it, hence changing the client is unavoidable. Only if the interface
isn't broken you can change the implementation without having the change
the clients.

  Can we derive any general lessons for interface design from
  that, rules that might have helped to impede the offending
  interface right from the start?

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