1.1 Program Development Using Erlang - Programming Rules and Conventions
2 | Ericsson AB. All Rights Reserved.: Program Development Using Erlang - Programming Rules and
Conventions
1 User's Guide
1.1 Program Development Using Erlang - Programming Rules and
Conventions
This paper lists some aspects which should be taken into consideration when specifying and programming software
systems using Erlang/OTP. It does not attempt to give a complete description of general specification and design
activities which are independent of the use of Erlang.
1.1.1 Structure and Erlang Terminology
Erlang systems are divided into modules. Modules are composed of functions and attributes. Functions are either only
visible inside a module or they are exported i.e. they can also be called by other functions in other modules. Attributes
begin with "-" and are placed in the beginning of a module.
The work in a system designed using Erlang is done by processes. A process is a job which can use functions in many
modules. Processes communicate with each other by sending messages. Processes receive messages which are sent to
them, a process can decide which messages it is prepared to receive. Other messages are queued until the receiving
process is prepared to receive them.
A process can supervise the existence of another process by setting up a bi-directional link to it. When a process
terminates, it automatically sends exit signals to the process to which it is linked. The default behavior of a process
receiving an exit signal is to terminate and to propagate the signal to its linked processes. A process can change this
default behavior by trapping exits, this causes all exit signals sent to a process to be turned into messages.
A pure function is a function that returns the same value given the same arguments regardless of the context of the
call of the function. This is what we normally expect from a mathematical function. A function that is not pure is
said to have side effects.
Side effects typically occur if a function a) sends a message b) receives a message c) calls exit d) calls any BIF which
changes a processes environment or mode of operation (e.g. get/1, put/2, erase/1, process_flag/2 etc).
Warning:
This document contains examples of bad code.
1.1.2 SW Engineering Principles
Structure the code into applications
The Erlang/OTP distribution is structured in so called Erlang applications. An Erlang application is not really part of the
Erlang language but it is part of the OTP design principles and there are many tools and API's that expect applications.
Applications have a predefined file structure both for source code, documentation and for the binaries used in runtime.
See also Applications in the OTP Design Principles.
5星 · 超过95%的资源 需积分: 9 153 浏览量
2012-05-24
23:09:40
上传
评论
收藏 95KB PDF 举报 
shanso2015-05-01比较难找，我打算翻译后部分吸引做为我们团队的规范
