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From: Olaf Rogalsky <olaf.rogalsky@aol.de>
To: help-gnu-emacs@gnu.org
Subject: understanding backquote
Date: Tue, 02 Jun 2015 21:17:37 +0200	[thread overview]
Message-ID: <87mw0hly26.fsf@aol.de> (raw)
In-Reply-To: 87vbf65jem.fsf@free.fr


Hi,

I have problems in understanding the semantics of backquote. Consider
the following function:

(defun test () `,(* (+ 1 2) (+ 3 4)))

Now let's have a look at the defintion of the symbol:

(symbol-function 'test)
=> (lambda nil (* (+ 1 2) (+ 3 4))) 

Huhh??? I was thinking, that the above definition is equivalent to the
following:

(defun test () 21)

Ok, this was unexpected, but perhaps the compiler does it "right":
(disassemble (byte-compile 'test))
=>  byte code:
      args: nil
    0       constant  21
    1       return    

Yes, it does. It is only, that I suspect, that this has nothing to do
with backquotes, but rather with constant folding optimization.

Can anybody explain this to me?

Thanks,
Olaf



  parent reply	other threads:[~2015-06-02 19:17 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-02 13:28 gtags-find-tag and gtags-find-rtag in C-code Peter Münster
2015-06-02 15:06 ` Eli Zaretskii
2015-06-02 16:01   ` Peter Münster
2015-06-02 16:13     ` Eli Zaretskii
2015-06-02 19:09       ` Dmitry Gutov
2015-06-02 20:34       ` Peter Münster
2015-06-02 19:17 ` Olaf Rogalsky [this message]
2015-06-03 11:05   ` understanding backquote Nicolas Richard
     [not found]   ` <mailman.4231.1433345880.904.help-gnu-emacs@gnu.org>
2015-06-03 18:53     ` Stefan Monnier
     [not found] ` <mailman.4175.1433272668.904.help-gnu-emacs@gnu.org>
2015-06-02 20:03   ` Pascal J. Bourguignon
2015-06-02 23:00     ` Olaf Rogalsky
2015-06-03 10:40       ` Nicolas Richard
     [not found]     ` <mailman.4191.1433286041.904.help-gnu-emacs@gnu.org>
2015-06-02 23:08       ` Pascal J. Bourguignon
2015-06-02 21:22   ` Barry Margolin
2015-06-02 22:53     ` Olaf Rogalsky
     [not found]     ` <mailman.4189.1433285612.904.help-gnu-emacs@gnu.org>
2015-06-02 23:07       ` Pascal J. Bourguignon
2015-06-02 23:54         ` Olaf Rogalsky
     [not found]         ` <mailman.4193.1433289260.904.help-gnu-emacs@gnu.org>
2015-06-03  1:14           ` Stefan Monnier
2015-06-03  7:57             ` Olaf Rogalsky
2015-06-03 10:23               ` Olaf Rogalsky
2015-06-03  2:37           ` Pascal J. Bourguignon

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