When is it right for a constructor to throw an exception?

Question

When is it right for a constructor to throw an exception? (Or in the case of Objective C: when is it right for an init\'er to return nil?)

It seems to me that a cons

Answer 1

Yes, if the constructor fails to build one of its internal part, it can be - by choice - its responsibility to throw (and in certain language to declare) an explicit exception , duly noted in the constructor documentation.

This is not the only option: It could finish the constructor and build an object, but with a method 'isCoherent()' returning false, in order to be able to signal an incoherent state (that may be preferable in certain case, in order to avoid a brutal interruption of the execution workflow due to an exception)
Warning: as said by EricSchaefer in his comment, that can bring some complexity to the unit testing (a throw can increase the cyclomatic complexity of the function due to the condition that triggers it)

If it fails because of the caller (like a null argument provided by the caller, where the called constructor expects a non-null argument), the constructor will throw an unchecked runtime exception anyway.