booking oop with Cardelli

11.7: oop considered bad:

. oop has extremely poor modularity properties

with respect to class extension and modification.

For example, it is easy to override a method

that should not be overridden,

or to reimplement a class in a way that

causes problems in subclasses.

Other large-scale development problems include

the confusion between classes and object types,

which limits the construction of abstractions,

and the fact that subtype polymorphism

is not good enough for expressing container classes .

Here are some things that could or should

be done to sofware engineering with respect to oop:

* Economy of execution.

Much can be done to improve the efficiency of method invocation

We also need to design type systems that can

statically check many of the conditions that now require

dynamic subclass checks.

* Economy of compilation.

the separate compilation of (sub)classes,

without resorting to recompilation of superclasses

and without relying on "private" information in interfaces.

* Economy of small-scale development.

improve error detection and the expressiveness of interfaces.

* Economy of large-scale development.

formulating and enforcing inheritance interfaces:

the contract between a class and its subclasses

(as opposed to the instantiation interface

which is essentially an object type).

Parametric polymorphism is beginning to appear

and its interactions with object-oriented features

need to be better understood.

Subtyping and subclassing must be separated.

Similarly, classes and interfaces must be separated.

* Economy of language features.

Prototype-based languages [provide simpler,

more composable features with orthogonality] .

How can we design powerful engineering

but also simple and reliable engineering?