GNU bug report logs - #26055
25.1; Eshell dollar expansion $var[i] not working

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Chunyang Xu <mail <at> xuchunyang.me>
To: bug-gnu-emacs <at> gnu.org
Subject: 25.1; Eshell dollar expansion $var[i] not working
Date: Sat, 11 Mar 2017 17:35:05 +0800

I execute the following commands in Eshell

~ $ setq l (quote (a b c))
(a b c)
~ $ echo $l[1]
~ $ nth 1 $l
b
~ $

I expect 'echo $l[1]' should print 'b'

~ $ setq s 'foo bar baz'
foo bar baz
~ $ echo $s[1]
~ $ nth 1 (split-string s)
bar
~ $ 

and 'echo $s[1]' should print 'bar' because in
(info "(eshell) Dollars Expansion") it says

‘$var[i]’
     Expands to the ‘i’th element of the value bound to ‘var’.  If the
     value is a string, it will be split at whitespace to make it a
     list.  Again, raises an error if the value is not a sequence.

Do I misunderstand this? Besides, the manual also says

‘$var[hello]’
     Calls ‘assoc’ on ‘var’ with ‘"hello"’, expecting it to be an alist
     (*note Association Lists: (elisp)Association List Type.).

it looks like to me they are using the same syntax, if so, how can
Eshell know which is which?

~ $ setq al (quote (("1" . one) ("2" . two)))
(("1" . one)
 ("2" . two))
~ $ echo $al[1]
one
~ $

Message #8 received at 26055 <at> debbugs.gnu.org (full text, mbox):

From: npostavs <at> users.sourceforge.net
To: Chunyang Xu <mail <at> xuchunyang.me>
Cc: 26055 <at> debbugs.gnu.org
Subject: Re: bug#26055: 25.1; Eshell dollar expansion $var[i] not working
Date: Tue, 14 Mar 2017 00:03:06 -0400

severity 26055 minor
tags 26055 confirmed
quit

Chunyang Xu <mail <at> xuchunyang.me> writes:

> I execute the following commands in Eshell
>
> ~ $ setq l (quote (a b c))
> (a b c)
> ~ $ echo $l[1]
> ~ $ nth 1 $l
> b
> ~ $
>
> I expect 'echo $l[1]' should print 'b'
>
> ~ $ setq s 'foo bar baz'
> foo bar baz
> ~ $ echo $s[1]
> ~ $ nth 1 (split-string s)
> bar
> ~ $ 
>
> and 'echo $s[1]' should print 'bar' because in
> (info "(eshell) Dollars Expansion") it says
>
> ‘$var[i]’
>      Expands to the ‘i’th element of the value bound to ‘var’.  If the
>      value is a string, it will be split at whitespace to make it a
>      list.  Again, raises an error if the value is not a sequence.
>
> Do I misunderstand this? Besides, the manual also says
>
> ‘$var[hello]’
>      Calls ‘assoc’ on ‘var’ with ‘"hello"’, expecting it to be an alist
>      (*note Association Lists: (elisp)Association List Type.).
>
> it looks like to me they are using the same syntax, if so, how can
> Eshell know which is which?
>
> ~ $ setq al (quote (("1" . one) ("2" . two)))
> (("1" . one)
>  ("2" . two))
> ~ $ echo $al[1]
> one
> ~ $

Since this apparently never worked it's hard to say what's supposed to
happen, but it looks like a 'number' property is added and then ignored.
Maybe something like this should be applied?

---   i/lisp/eshell/esh-var.el
+++   w/lisp/eshell/esh-var.el
@@ -562,8 +562,10 @@ eshell-apply-indices
   value)
 
 (defun eshell-index-value (value index)
   "Reference VALUE using the given INDEX."
+  (when (and (stringp index) (get-text-property 0 'number index))
+    (setq index (string-to-number index)))
   (if (stringp index)
       (cdr (assoc index value))
     (cond
      ((ring-p value)

Message #15 received at 26055 <at> debbugs.gnu.org (full text, mbox):

From: npostavs <at> users.sourceforge.net
To: Chunyang Xu <mail <at> xuchunyang.me>
Cc: 26055 <at> debbugs.gnu.org
Subject: Re: bug#26055: 25.1; Eshell dollar expansion $var[i] not working
Date: Fri, 09 Jun 2017 20:33:26 -0400

[Message part 1 (text/plain, inline)]

tags 26055 patch
quit

npostavs <at> users.sourceforge.net writes:

> Since this apparently never worked it's hard to say what's supposed to
> happen, but it looks like a 'number' property is added and then ignored.
> Maybe something like this should be applied?

Since `eshell-lisp-command' does the conversion of strings marked with
'number', I think it's correct to make eshell-index-value do so as well.

[v1-0001-Handle-integer-indices-for-eshell-variables-Bug-2.patch (text/x-diff, inline)]

From bacbb41ab4d5539d284b1a540e70779a49c00e25 Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs <at> gmail.com>
Date: Fri, 9 Jun 2017 19:40:38 -0400
Subject: [PATCH v1] Handle integer indices for eshell variables (Bug#26055)

* lisp/eshell/esh-var.el (eshell-index-value): Convert index to number
if it's been marked as one, just like `eshell-lisp-command' does.
---
 lisp/eshell/esh-var.el | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lisp/eshell/esh-var.el b/lisp/eshell/esh-var.el
index fe1f1188c8..cdd05bd7e9 100644
--- a/lisp/eshell/esh-var.el
+++ b/lisp/eshell/esh-var.el
@@ -563,6 +563,8 @@ (defun eshell-apply-indices (value indices)
 
 (defun eshell-index-value (value index)
   "Reference VALUE using the given INDEX."
+  (when (and (stringp index) (get-text-property 0 'number index))
+    (setq index (string-to-number index)))
   (if (stringp index)
       (cdr (assoc index value))
     (cond
-- 
2.11.1

Message #20 received at 26055 <at> debbugs.gnu.org (full text, mbox):

From: npostavs <at> users.sourceforge.net
To: Chunyang Xu <mail <at> xuchunyang.me>
Cc: 26055 <at> debbugs.gnu.org
Subject: Re: bug#26055: 25.1; Eshell dollar expansion $var[i] not working
Date: Sat, 17 Jun 2017 00:17:52 -0400

tags 26055 fixed
close 26055 26.1
quit

npostavs <at> users.sourceforge.net writes:

>> Since this apparently never worked it's hard to say what's supposed to
>> happen, but it looks like a 'number' property is added and then ignored.
>> Maybe something like this should be applied?
>
> Since `eshell-lisp-command' does the conversion of strings marked with
> 'number', I think it's correct to make eshell-index-value do so as well.

Pushed to master [1: 27c194995b].

[1: 27c194995b]: 2017-06-17 00:10:33 -0400
  Handle integer indices for eshell variables (Bug#26055)
  http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=27c194995b460b79e8e62e0d21e85d87df664649

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