From: "Štěpán Němec" <stepnem@gmail.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: mattiase@acm.org, emacs-devel@gnu.org
Subject: Re: Regexp bytecode disassembler
Date: Sat, 21 Mar 2020 21:44:49 +0100 [thread overview]
Message-ID: <871rpl77zy.fsf@gmail.com> (raw)
In-Reply-To: <83y2rtcux2.fsf@gnu.org>
On Sat, 21 Mar 2020 22:30:49 +0200
Eli Zaretskii wrote:
>> Do you mean you would prefer to use `cond' and rewrite all those clauses
>> to something like the following?
>>
>> (cond
>> ((eql opcode 0) (cons 'no-op 1))
>> ((eql opcode 1) (cons 'succeed 1))
>
> Yes.
>
>> Maybe readability is much more subjective than I thought, but I find the
>> latter very suboptimal, to say the least.
>
> Why "suboptimal"?
It's unnecessarily verbose and most of that is just repetition, i.e.
noise, which makes it harder to read. It _begs_ to be rewritten with
(p)case. :-)
>> Also, isn't "just selecting from a list of fixed values" precisely the
>> reason to use some sort of case/switch instead of the general `cond'?
>
> 'cond' _is_ a case/switch construct.
I have to disagree. `cond' is a general conditional construct: all the
clauses are completely independent, testing for anything, whereas in a
`case' you have one object that is tested against each clause. Which is
precisely the case here.
>> Certainly `pcase' can also be useful in more complicated use cases, but
>> it will expand to the cond form anyway, so I also don't see any
>> performance concerns.
>
> I said nothing about the performance.
OK. I was just trying to come up with some other possible factors, as I
found the readability argument so surprising.
--
Štěpán
next prev parent reply other threads:[~2020-03-21 20:44 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-20 12:27 Regexp bytecode disassembler Mattias Engdegård
2020-03-20 12:58 ` Andreas Schwab
2020-03-20 14:34 ` Eli Zaretskii
2020-03-21 16:52 ` Mattias Engdegård
2020-03-21 19:19 ` Eli Zaretskii
2020-03-21 20:16 ` Štěpán Němec
2020-03-21 20:30 ` Eli Zaretskii
2020-03-21 20:40 ` Mattias Engdegård
2020-03-21 20:44 ` Štěpán Němec [this message]
2020-03-22 14:12 ` Eli Zaretskii
2020-03-22 14:43 ` Štěpán Němec
2020-03-22 16:55 ` Eli Zaretskii
2020-03-22 17:16 ` Štěpán Němec
2020-03-22 17:30 ` Eli Zaretskii
2020-03-22 18:34 ` Paul Eggert
2020-03-22 18:36 ` Dmitry Gutov
2020-03-21 20:50 ` Dmitry Gutov
2020-03-21 23:58 ` Drew Adams
2020-03-22 0:02 ` Drew Adams
2020-03-21 20:37 ` Mattias Engdegård
2020-03-22 3:28 ` Eli Zaretskii
2020-03-22 9:23 ` Mattias Engdegård
2020-03-22 10:37 ` Eli Zaretskii
2020-03-22 15:24 ` Mattias Engdegård
2020-03-22 17:06 ` Eli Zaretskii
2020-03-22 19:39 ` Mattias Engdegård
2020-03-22 20:12 ` Eli Zaretskii
2020-03-22 20:22 ` Corwin Brust
2020-03-20 15:39 ` Pip Cet
2020-03-21 16:56 ` Mattias Engdegård
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