From: Jean Louis <bugs@gnu.support>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: help-gnu-emacs@gnu.org
Subject: Re: How to tame compiler?
Date: Sat, 1 May 2021 09:34:06 +0300 [thread overview]
Message-ID: <YIz2Xs14+Y4tmPTX@protected.localdomain> (raw)
In-Reply-To: <jwvwnsj5d4y.fsf-monnier+emacs@gnu.org>
* Stefan Monnier <monnier@iro.umontreal.ca> [2021-05-01 06:50]:
> > Independent from the question whether your usage of `eval' is good or
> > valid - there must be some real problem here: if the compiler tells that
> > the lexical variables are unused, their values will not be available in
> > you `eval' call - you would have to create dynamical bindings for that.
>
> I know I sound like a broken clock, but I think a better answer is to
> avoid `eval`: instead of taking expressions (that you'd pass to `eval`)
> arrange to receive functions (which you'd pass to `funcall` or `apply`).
> Then you can pass those functions the data they need (e.g. the value of
> things like `unsubscribe-text`).
I have to understand it in this example:
The HTML template is following and it is string:
<html>
<head>
<title>⟦ xml-escape title ⟧</title>
</head>
<body>
<p>Today is one US dollar this many euros: ⟦ usd-eur 1 ⟧</p>
</body>
</html>
> I know I sound like a broken clock, but I think a better answer is to
> avoid `eval`: instead of taking expressions (that you'd pass to `eval`)
> arrange to receive functions (which you'd pass to `funcall` or `apply`).
> Then you can pass those functions the data they need (e.g. the value of
> things like `unsubscribe-text`).
Does that mean I should now extract maybe function `xml-escape' and use apply with rest of arguments?
Maybe instead of:
<title>⟦ xml-escape title ⟧</title>
I should make:
<title>⟦ xml-escape title ⟧</title>
And then apply xml-escape with "title".
Then I would convert first word into function, that somehow
works, but all the remaining parts of string still need to be
converted. How is program to know that things in a string are for
example other variables or other Lisp functions?
(let* ((lisp (buffer-substring-no-properties
(1+ (match-beginning 0)) (1- (match-end 0))))
(lisp (split-string lisp))
(function (pop lisp))
(_ (message "%s" function))
(value (apply (intern function) lisp)) ;; I am stuck here
(value (string-or-empty-string value)))
For simplest use case like converting string to variable, or something like:
⟦ var hello-name ⟧
I think that would work, but then if I only use variables, I
would not need "var" there, I could just interpolate it into
variable without eval.
For the case where there is even slightly complex Lisp like ⟦ (usd-eur (gold-price-kg)) ⟧
I would not know what to do there.
Maybe it could look like:
⟦ usd-eur (gold-price-kg) ⟧
But then again program would receive string "(gold-price-kg)" and
how would I know that string is another function? I would need to
extract that string and basically make small Lisp reader, again
we come to kind of eval-ing it.
I want to know if there is way to do it.
--
Jean
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next prev parent reply other threads:[~2021-05-01 6:34 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-22 14:43 How to tame compiler? Jean Louis
2021-04-22 14:46 ` Stefan Monnier
2021-04-22 15:47 ` Jean Louis
2021-04-22 16:06 ` Jean Louis
2021-04-30 13:31 ` Jorge P. de Morais Neto
2021-04-30 19:38 ` rcd-template-eval - was " Jean Louis
2021-04-30 19:48 ` rcd-template-eval, much is in Org mode Jean Louis
2021-04-30 20:06 ` Tassilo Horn
2021-04-30 22:08 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-04-30 23:04 ` Org mode rant Jean Louis
2021-05-01 0:46 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-01 6:10 ` Jean Louis
2021-05-01 6:34 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-01 9:41 ` On markdown images Jean Louis
2021-05-01 9:59 ` Yuri Khan
2021-05-01 10:18 ` Jean Louis
2021-05-01 11:09 ` Yuri Khan
2021-05-01 11:25 ` Jean Louis
2021-05-02 19:30 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-03 5:43 ` Yuri Khan
2021-05-03 17:08 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-03 23:22 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-04 2:39 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-01 5:00 ` Org mode rant Bastien
2021-05-01 5:10 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-01 9:16 ` Jean Louis
2021-05-01 10:06 ` Bastien
2021-05-01 10:42 ` Jean Louis
2021-05-01 10:10 ` Bastien
2021-05-01 11:19 ` Jean Louis
2021-05-01 13:48 ` [External] : " Drew Adams
2021-05-01 14:05 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-01 10:10 ` Bastien
2021-04-30 20:23 ` eval myths - Re: How to tame compiler? Jean Louis
2021-04-30 22:11 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-04-30 23:07 ` Jean Louis
2021-05-01 0:28 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-01 8:13 ` tomas
2021-04-30 22:06 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-04-30 22:20 ` Stefan Monnier
2021-04-30 22:31 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-04-30 22:50 ` Stefan Monnier
2021-04-30 22:56 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-01 0:44 ` Michael Heerdegen
2021-05-01 3:49 ` Stefan Monnier
2021-05-01 4:55 ` Michael Heerdegen
2021-05-01 6:34 ` Jean Louis [this message]
2021-05-01 13:38 ` Stefan Monnier
2021-05-01 16:19 ` Jean Louis
2021-05-02 5:41 ` Michael Heerdegen
2021-05-02 7:37 ` Jean Louis
2021-05-02 7:45 ` Jean Louis
2021-05-02 9:06 ` tomas
2021-05-02 11:18 ` Jean Louis
2021-05-02 12:24 ` tomas
2021-05-02 18:17 ` Jean Louis
2021-05-02 12:06 ` Stages of WWW development compared to Emacs Lisp development Jean Louis
2021-05-02 16:51 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-02 18:37 ` Jean Louis
2021-05-02 16:45 ` How to tame compiler? Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-02 22:29 ` Stefan Monnier
2021-05-02 23:14 ` Jean Louis
2021-05-03 1:58 ` Eduardo Ochs
2021-05-03 6:51 ` Eval in templates - " Jean Louis
2021-05-01 4:53 ` Michael Heerdegen
2021-05-01 7:05 ` Jean Louis
2021-05-01 7:59 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-01 6:03 ` Jean Louis
2021-05-01 6:17 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-02 5:58 ` Michael Heerdegen
2021-05-02 6:54 ` Jean Louis
2021-05-03 21:39 ` Jean Louis
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