Re: [Xen-devel] [PATCH] cmdline: treat hyphens and underscores the same

From: Jan Beulich <jbeulich@suse.com>
To: George Dunlap <george.dunlap@citrix.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Julien Grall <julien@xen.org>, Wei Liu <wl@xen.org>,
	Konrad Wilk <konrad.wilk@oracle.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <ian.jackson@citrix.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [Xen-devel] [PATCH] cmdline: treat hyphens and underscores the same
Date: Mon, 9 Dec 2019 15:11:09 +0100	[thread overview]
Message-ID: <359882b9-e6a4-508e-d339-841a021efa09@suse.com> (raw)
In-Reply-To: <fee3e4ec-213b-c3a9-a509-a125877be6f3@citrix.com>

On 09.12.2019 15:06, George Dunlap wrote:
> On 12/6/19 4:42 PM, Jan Beulich wrote:
>> On 06.12.2019 17:20, Julien Grall wrote:
>>> Hi,
>>>
>>> On 06/12/2019 16:06, Jan Beulich wrote:
>>>> On 06.12.2019 15:46, Julien Grall wrote:
>>>>> On 05/12/2019 16:50, Jan Beulich wrote:
>>>>>> On 05.12.2019 17:27, Julien Grall wrote:
>>>>>>> On 05/12/2019 15:33, Jan Beulich wrote:
>>>>>>>> +/*
>>>>>>>> + * String comparison functions mostly matching strcmp() / strncmp(),
>>>>>>>> + * except that they treat '-' and '_' as matching one another.
>>>>>>>> + */
>>>>>>>> +static int _strcmp(const char *s1, const char *s2)
>>>>>>>
>>>>>>> I thought we were trying to avoid new function name with leading _?
>>>>>>
>>>>>> We're trying to avoid new name space violations. Such are
>>>>>> - identifiers starting with two underscores,
>>>>>> - identifiers starting with an underscore and an upper case letter,
>>>>>> - identifiers of non-static symbols starting with an underscore.
>>>>>
>>>>> I am not sure to understand why non-static symbols only. This would
>>>>> prevent you to use the the non-static symbol if you happen to re-use the
>>>>> same name.
>>>>
>>>> I'm afraid I don't understand. Anyway - what I've listed above is
>>>> what the language standard mandates.
>>> AFAIU, for a given unit, there is only one pool of identifiers. So you 
>>> could not have an identifier used at the same time by a non-static and a 
>>> static symbol (that's exclusing the weak attribute). So it feels 
>>> slightly strange to only cover the non-static symbols.
>>
>> I guess I'm still not getting your point. What the above tells
>> us is that static symbols may start with an underscore (but
>> not followed by another one or an uppercase letter). Non-static
>> symbols may not.
>>
>>>>> Anyway, how about calling it cmdline_strncmp()? This would be easier to
>>>>> spot misuse on review (i.e using strncmp() rather than _strncmp()).
>>>>
>>>> We already have cmdline_strcmp(), or else I would indeed have used
>>>> this prefix. No prefix (other than the lone underscore) seemed the
>>>> next best option.
>>>
>>> As we parse an option, how about opt_strncmp()?
>>
>> I'd still like _strncmp() better here.
> 
> Why?  It doesn't tell you anything at all about what's special about the
> function.  In fact, I'd say it's confusing -- the "_" doesn't normally
> mean, "do something different and special", but "do the core of
> something which other things might call".
> 
> I'd much prefer opt_strncmp() than _strncmp().

Noted - will do.

Jan

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