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From:   Eric Sunshine <sunshine@sunshineco.com>
Date:   Fri, 8 May 2020 11:38:34 -0400
Message-ID: <CAPig+cQP_9onrq-z5db1GhXSSHaeKJ+UhNewWP25wLCsMRzSrA@mail.gmail.com>
Subject: Re: Re* [PATCH v4] submodule: port subcommand 'set-url' from shell to C
To:     Junio C Hamano <gitster@pobox.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>
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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 '=='. 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.

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).