linux-kernel - Re: [PATCH] drivers/scsi/aic7xxx_old: Convert to generic boolean-values

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Date:	Fri, 16 Feb 2007 19:04:11 +0100
From:	Richard Knutsson <ricknu-0@...dent.ltu.se>
To:	James Bottomley <James.Bottomley@...elEye.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: [PATCH] drivers/scsi/aic7xxx_old: Convert to generic boolean-values

James Bottomley wrote:
> On Mon, 2007-02-12 at 12:27 -0800, Andrew Morton wrote:
>   
>> Given that we now have a standard kernel-wide, c99-friendly way of
>> expressing true and false, I'd suggest that this decision can be revisited.
>>
>> Because a "true" is significantly more meaningful (and hence readable)
>> thing than a bare "1".
>>     
>
> OK, I'm really not happy with doing this for three reasons:
>
> 1. It's inviting huge amounts of driver churn changing bitfields to
> booleans
>   
Have been some work done already. Has there been any problems?
> 2. I do find it to be a readability issue.  Like most driver writers,
> I'm used to register layouts, and those are simple bitfields, so I don't
> tend to think true and false, I think 1 and 0.
>   
It is a fundamental difference between an integer and a boolean. Have 
you seen anyone trying to do "bool var = true + true;"? ;)
> 3. Having a different, special, type for single bit bitfields (while
> still using u<n> for multi bit bitfields) is asking for confusion, and
> hence trouble at the driver level.
>   
I don't think a boolean should be view as a single bit bitfield. Ex:
u8 a:1;
...
int b = 4 + a;
is obviously not a boolean, while:
u8 a:1;
...
if (a)
is, and a should be "bool a:1;" (imho)


Richard Knutsson

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