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From: Eric Abrahamsen <eric@ericabrahamsen.net>
To: emacs-devel@gnu.org
Subject: Re: defsubst VS defun or defmacro [was RE: Compiled code in Emacs-26 will fail in Emacs-25 if use pcase]
Date: Thu, 23 Feb 2017 20:20:21 -0800	[thread overview]
Message-ID: <87bmtsfce2.fsf@pellet> (raw)
In-Reply-To: p91o9xs6y3g.fsf@google.com

raman <raman@google.com> writes:

> The rule of thumb I've used over the years:
>
> 1. Never use defmacro except when creating a special-form or special
> notation AKA DSL 
>
> 2. Use defun except for short and often repeated forms that also need
> speed, then I've used defsubst because they behave like functions for
> all practical purposes such as mapcar.

Good, these were the principles I was working from, though in my case I
had no empirical data to support them :)

> 3. I had done some timing in the early days of emacspeak, including
> looking at what M-x disassemble produced, then tighten the inner loop of
> emacspeak appropriately with defsubst.
>
> 4. What just broke is  calls to defsubst-defined functions from within
> other defsubst --- independent of our various views on the misguidedness
> or otherwise of defsubst, I believe this is a bug that might be worth
> fixing since it breaks  working code in mysterious and unpredictable ways.

Okay, makes sense. I've never been tempted to use defsubsts for anything
more than two-liners, but I'll keep an eye on this.

Thanks!
Eric




  reply	other threads:[~2017-02-24  4:20 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-06 17:50 [PATCH]: Add new bytecode op `switch' for implementing branch tables Vibhav Pant
2017-02-06 18:30 ` Stefan Monnier
2017-02-07  8:45   ` Vibhav Pant
2017-02-07 14:41     ` Stefan Monnier
     [not found]       ` <CA+T2Sh3N09WGoHtNL3BbptsKA1ZdwWedTNDd0vmeBe0fTO5a1g@mail.gmail.com>
     [not found]         ` <CA+T2Sh2sa6=WOvyePzL_ACR0Nw=jTnZze_xXFcvL=22OURP=ZA@mail.gmail.com>
2017-02-07 15:21           ` Vibhav Pant
2017-02-07 13:50   ` Vibhav Pant
2017-02-07 15:56     ` Clément Pit-Claudel
2017-02-08 13:38       ` Vibhav Pant
2017-02-08 16:21         ` Vibhav Pant
2017-02-08 17:46           ` Vibhav Pant
2017-02-09 13:21           ` Stefan Monnier
2017-02-08 17:56         ` Eli Zaretskii
2017-02-23  4:35           ` Compiled code in Emacs-26 will fail in Emacs-25 if use pcase [was: Add new bytecode op `switch' for implementing branch tables.] Tino Calancha
2017-02-23  8:36             ` Richard Copley
2017-02-23 10:12               ` Tino Calancha
2022-07-04 12:24               ` Vibhav Pant
2017-02-23 13:39             ` Stefan Monnier
2017-02-23 14:33               ` Kaushal Modi
2017-02-23 15:10                 ` Stefan Monnier
2022-07-02 20:31                   ` Robert Weiner
2022-07-02 21:28                     ` Stefan Monnier
     [not found]               ` <CA+T2Sh29UhuNrhRZG=PPQbYYHtONXwyb8dX4rBVLmwdORLELhg@mail.gmail.com>
2017-02-23 17:50                 ` Vibhav Pant
2017-04-11 17:40               ` Compiled code in Emacs-26 will fail in Emacs-25 if use pcase Lars Brinkhoff
2017-02-23 16:15             ` Compiled code in Emacs-26 will fail in Emacs-25 if use pcase [was: Add new bytecode op `switch' for implementing branch tables.] raman
2017-02-23 17:24               ` Drew Adams
2017-02-23 17:50                 ` T.V Raman
2017-02-23 18:02                   ` Drew Adams
2017-02-23 18:24                     ` T.V Raman
2017-02-23 19:00                       ` Drew Adams
2017-02-24  2:06                       ` defsubst VS defun or defmacro [was RE: Compiled code in Emacs-26 will fail in Emacs-25 if use pcase] Tino Calancha
2017-02-24  3:14                         ` Eric Abrahamsen
2017-02-24  3:56                           ` raman
2017-02-24  4:20                             ` Eric Abrahamsen [this message]
2017-02-24  3:51                         ` raman
2017-02-09 17:32         ` [PATCH]: Add new bytecode op `switch' for implementing branch tables Clément Pit-Claudel
2017-02-09 19:15         ` Clément Pit-Claudel
2017-02-10  4:12           ` Vibhav Pant
2017-02-10  4:17             ` Clément Pit-Claudel
2017-02-10  5:03               ` Vibhav Pant
2017-02-10  6:07                 ` Stefan Monnier
2017-02-10 13:51                   ` Vibhav Pant
2017-02-10 15:12                     ` Stefan Monnier
2017-02-10 17:59                       ` Vibhav Pant
2017-02-10 18:25                         ` Vibhav Pant
2017-02-10 20:47                           ` Paul Eggert
2017-02-10 20:58                             ` Stefan Monnier
2017-02-11 15:07                             ` Vibhav Pant
2017-02-12  3:10                               ` Vibhav Pant
2017-02-13  7:18                                 ` Vibhav Pant
2017-02-09 16:37       ` Vibhav Pant
2017-02-06 19:32 ` Eli Zaretskii
2017-02-07 14:26   ` Vibhav Pant
2017-02-07 16:14     ` Eli Zaretskii

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