Re: Why =?UTF-8?B?Q2Fu4oCZdCBZb3UgSW1wb3J0IFBhY2thZ2VzPw==?=

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 20 Feb 2011 11:20:06 -0500

Message-ID:

<ijrevf$9d8$1@news.albasani.net>

Arved Sandstrom wrote:

I'm absolutely not going to say that your proposed use of packages is wrong.
We know that Java packages are used to provide a namespace mechanism - that's
the primary purpose - and as an obvious corollary programmers then often use
packages to group their classes by functionality. But I don't believe that it

According to the Java tutorial at
http://download.oracle.com/javase/tutorial/java/concepts/package.html
"A package is a namespace that organizes a set of related classes and interfaces."

So grouping related types is an explicit purpose of the namespaces.

The JLS, Chapter 7, "Packages", states, "Each package has its own set of names
for types, which helps to prevent name conflicts."

So prevention of name conflicts is, according to the JLS, a primary purpose of
packages.

follows from this primary purpose of packages - unique namespaces - that your
proposed use is a _recommendation_. I don't think it's an _incorrect_ use, and
if it makes your APIs and implementations easier to design, implement and use,
so much the better.

In this particular problem domain I think you could make a decent opposing
argument that rather than have

org.ahs.database.platforms.oracle.Platform
org.ahs.database.platforms.mysql.Platform

it still makes more sense to have

org.ahs.database.platforms.OraclePlatform
org.ahs.database.platforms.MySqlPlatform

because the _classes_ are _not_ the same. One is customized for Oracle, one
for MySQL. Assuming that both inherit from a
org.ahs.database.platforms.Platform class, say, it's not like I'll have
explicit references to MySqlPlatform all over the place; in most cases I'll be
referring to Platform anyway.

Like I say, I don't doubt that there are situations where your proposed
package structure makes more sense. A lot of different factors would come into
it. Main thing is, I don't believe that the purpose of Java packages dictates
or recommends either approach.

I agree with your recommendations for package structure.

--
Lew
Honi soit qui mal y pense.