unofficial mirror of help-gnu-emacs@gnu.org
 help / color / mirror / Atom feed
From: Barry Margolin <barmar@alum.mit.edu>
To: help-gnu-emacs@gnu.org
Subject: Re: Macro Expansion Inconsistency
Date: Wed, 17 Dec 2014 10:53:48 -0500	[thread overview]
Message-ID: <barmar-8B89DD.10534817122014@88-209-239-213.giganet.hu> (raw)
In-Reply-To: mailman.16290.1418825041.1147.help-gnu-emacs@gnu.org

In article <mailman.16290.1418825041.1147.help-gnu-emacs@gnu.org>,
 Alexander Shukaev <haroogan@gmail.com> wrote:

> Thank you very much, John and Nicolas. I think I finally understand how
> macros expand in Emacs Lisp better now. I'm sure it's not a coincidence
> that you both came up with almost identical solutions. It suggests that the
> style of returning forms for evaluation from macro is probably the best way
> to go in most cases when `let' is involved.

Not just "probably the best" -- this is the ONLY way to go in macros. 
The whole point of macros is to produce new code to be evaluated in 
place of the original code.

The important thing to remember about macros is that they run when 
you're COMPILING the code, not when you run it. These may be 
approximately the same time if you evaluate the calling code (e.g. by 
typing it into the *scratch* buffer, loading the source file, M-x 
eval-region). This is why calling eval seems to work when you're testing 
the macro interactively.

But if you byte-compile the file, it will be run then, not when you 
later load the .elc file. This will usually be a totally different Emacs 
session, so it should be obvious why the results of calling eval won't 
be available then.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***


  parent reply	other threads:[~2014-12-17 15:53 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <mailman.16228.1418763453.1147.help-gnu-emacs@gnu.org>
2014-12-16 21:10 ` Macro Expansion Inconsistency Joost Kremers
2014-12-16 21:25   ` Alexander Shukaev
2014-12-16 21:46     ` John Mastro
2014-12-16 22:58       ` Alexander Shukaev
2014-12-16 23:14         ` Alexander Shukaev
2014-12-17  2:19           ` Alexander Shukaev
2014-12-17 10:04             ` Nicolas Richard
2014-12-17 14:03               ` Alexander Shukaev
2014-12-17 14:20                 ` Stefan Monnier
2014-12-17 14:34                   ` Alexander Shukaev
2014-12-17 14:21                 ` Nicolas Richard
2014-12-17 14:52                   ` Alexander Shukaev
2014-12-17 14:58                     ` Nicolas Richard
2014-12-17 15:14                       ` Alexander Shukaev
     [not found]               ` <mailman.16290.1418825041.1147.help-gnu-emacs@gnu.org>
2014-12-17 15:53                 ` Barry Margolin [this message]
2014-12-17 16:01                   ` Alexander Shukaev
     [not found]           ` <mailman.16262.1418782759.1147.help-gnu-emacs@gnu.org>
2014-12-17  3:03             ` Rusi
2014-12-17  9:21               ` Nicolas Richard
2014-12-16 23:20         ` John Mastro
     [not found]           ` <CAKu-7WzgoHH=zM_jxeVGMwzAne88nAoCUsLKQv9zUYo_amsjNg@mail.gmail.com>
2014-12-17  3:34             ` John Mastro
2014-12-17  3:41               ` John Mastro
2014-12-16 23:30   ` Stefan Monnier
2014-12-16 20:57 Alexander Shukaev

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://www.gnu.org/software/emacs/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=barmar-8B89DD.10534817122014@88-209-239-213.giganet.hu \
    --to=barmar@alum.mit.edu \
    --cc=help-gnu-emacs@gnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).