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Date: Fri, 07 Mar 2003 20:58:17 +0200
From: =?ISO-8859-1?Q?Johan_Sj=F6berg?= <johan.sjoberg@avaintec.com>
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To: Avalon Developers List <dev@avalon.apache.org>
Subject: Re: Coding style question: backwards null checks
References: <20030307141624.GE3905@expresso.localdomain>
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Berin Loritsch wrote:
> Jeff Turner wrote:

>> So is there any other reason for this?  Can I do a massive grep for 
>> 'null !=' and change these?
> 
> 
> No, I think that is the major reason.

I remember a discussion between Peter D. and someone here on the list 
about this. I can't find it in the web archive so I include it from my 
local history. It might not be interesting though.

<INCLUDED-MESSAGE>

At 08:24  1/12/00 -0500, you wrote:

 >Just a stylistic nit-pick:
 >
 >I noticed you committed a change that does nothing
 >but change the style of the code.  Let me explain
 >why I do it the way I do.
 >
 >regarding "if (null != message) ...":
 >
 >to me this is not semantically correct, it is kind
 >of backwards.  We are not checking if null is
 >message, but if message is null.  I also think that
 >by keeping it "if (message != null) ..." it is more
 >readable and understandable by most English speaking
 >folks.


I used to agree .. thou apparently we are wrong ;) (Had an argument with 
a professor over this one time ;] ) The reason basically comes down to
expectations. "if( XXX == ... )" where XXX is any immutable-constant 
(like integer values, floats, nulls) is meant to facilitate 
understanding. It helps you understand the difference between 
"constants" and l-vars (or whatever they are called). Students who were 
taught "if( XXX == ... )" gain a "deeper" understanding of programming 
language. In some languages (namely c/c++) it also has added benefit of 
using compiler to check you don't have single '=' etc - thou this is for 
all purposes not relevent to java.

<SNIP/>

Cheers,

Pete

</INCLUDED-MESSAGE>

Perhaps there is something to that, but ( null == arg ) still twists my 
head after some time spent on reading Avalon code ;)

Cheers,

//
Johan


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