[R-pkg-devel] tibbles are not data frames

[Hadley Wickham]

On Tue, Sep 26, 2017 at 8:28 AM, Jeroen Ooms <jeroenooms at gmail.com> wrote:
> On Tue, Sep 26, 2017 at 11:56 AM, Gábor Csárdi <csardi.gabor at gmail.com> wrote:
>>
>> On Tue, Sep 26, 2017 at 10:35 AM, Joris Meys <Joris.Meys at ugent.be> wrote:
>> > I don't like the dropping of dimensions either. That doesn't change the
>> > fact that a tibble reacts different from a data.frame. So tibbles do not
>> > inherit correctly from the class data.frame, and it can thus be argued that
>> > it's against OOP paradigms to pretend tibbles inherit from the class
>> > data.frame.
>>
>> I have yet to see an OOP system in which a subclass cannot override the methods
>> of its superclass. Not only is this in line with OOP paradigms, it is
>> actually one of the essential OOP features.
>
> Not if this compromises type safety. Formal OOP languages enforce the
> signature matches when you override a method. The fact that R is
> dynamically typed puts this responsibility at the developer. The fact
> that tibble [ returns a data frame where it's parent class returns an
> atomic vector violates this principle, resulting in the obvious type
> errors where tibbles are used as data frames.

Where its parent class _sometimes_ returns an atomic vector and
_sometimes_ returns a data frame.

Hadley

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