Public Interface

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Public Interface

DESIGN

Guidance

A project must provide additional documents that describe plans and procedures that can be used to evaluate the project’s compliance.

Provide an architecture design document.

Provide a coding standards document.

Provide a software release plan document.

Provide a document with a plan for deprecating obsolete interfaces.

Create fully insulated classes.

Insulate public interfaces from compile-time dependencies.

Best practices

Present complete and coherent sets of concepts to the user.

Design interfaces to be statically typed.

Minimize the interface’s dependencies on other interfaces.

Express interfaces in terms of application-level types.

Use assertions only to aid development and integration.

Examples

C++ interface

::The characteristics of a protocol class are:

It neither contains nor inherits from classes that contain member data, non-virtual functions, or private (or protected) members of any kind.

It has a non-inline virtual destructor defined with an empty implementation.

All member functions other than the destructor, including inherited functions, are declared pure virtual and left undefined.

Benefits

The benefits of using protocol classes include:

Insulating applications from the external client

Insulating changes that are internal to the interface

Insulating changes to the public interface from changes to the implementation of the interface

Insulation has costs, but these tend to be outweighed by the gains in interoperability and reusability.

Costs

Going through the implementation pointer

Addition of one level of indirection per access

Addition of the size of the implementation pointer per object to memory requirements

REFERENCES

Various methodologies, such as Refactoring , support the determination of interfaces. Refactoring generally applies to the entire software implementation, but is especially helpful in properly flushing out interfaces.

There are other approaches defined through the pattern community. You can obtain these methodologies from the pattern community at {Link without Title} .

See "Java Design: Building Better Apps & Applets" for a good introductory methodology that also applies to the C/C++ community.