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From:   Junio C Hamano <gitster@pobox.com>
To:     Eric Sunshine <sunshine@sunshineco.com>
Cc:     Christian Couder <christian.couder@gmail.com>,
        Shourya Shukla <shouryashukla.oo@gmail.com>,
        chrisitan.couder@gmail.com, Denton Liu <liu.denton@gmail.com>,
        git <git@vger.kernel.org>
Subject: Re: Re* [PATCH v4] submodule: port subcommand 'set-url' from shell to C
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Date:   Fri, 08 May 2020 08:57:09 -0700
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        (Eric Sunshine's message of "Fri, 8 May 2020 11:38:34 -0400")
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Eric Sunshine <sunshine@sunshineco.com> writes:

> On Fri, May 8, 2020 at 11:18 AM Junio C Hamano <gitster@pobox.com> wrote:
>> + - Do not explicitly compare an integral value with constant 0 or a
>> +   pointer value with constant NULL for equality; just say !value
>> +   instead.  To validate a counted array at ptr that has cnt elements
>> +   in it, write:
>> +
>> +       if (!ptr || !cnt)
>> +               BUG("array should not be empty at this point");
>> +
>> +   and not:
>> +
>> +       if (ptr == NULL || cnt == 0);
>> +               BUG("array should not be empty at this point");
>
> This talks only about '=='.

Yup.  The text would need a matching change, though.

> People might still use 0 or NULL with
> '!='. I wonder if the example can include '!=', as well. Perhaps:
>
>     if (!ptr)
>         BUG("...");
>     if (cnt)
>         foo(ptr, cnt);
>
> instead of:
>
>     if (ptr == NULL)
>         BUG("...");
>     if (cnt != 0)
>         foo(ptr, cnt);
>
> or something.

Or more succinctly:

	if (!ptr || cnt)
		BUG("we must have an empty array at this point");

perhaps?

> Also, would you want to talk about not comparing against NUL character?
>
>     if (*s)
>         foo(s);
>
> instead of:
>
>     if (*s != '\0')
>         foo(s);
>
> Maybe that's overkill since NUL is an integral value which is already
> covered by your earlier statement (but perhaps some people would
> overlook that).

Yeah, it might be worth saying it explicitly.  I dunno.