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bug#18059: 24.3.92; defvar and special variables
From: |
Noam Postavsky |
Subject: |
bug#18059: 24.3.92; defvar and special variables |
Date: |
Sat, 10 Feb 2018 14:29:52 -0500 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.0.90 (gnu/linux) |
tags 18059 + patch
quit
Michael Heerdegen <michael_heerdegen@web.de> writes:
>>From eval.c:
>
> /* A simple (defvar foo) with lexical scoping does "nothing" except
> declare that var to be dynamically scoped *locally* (i.e. within
> the current file or let-block). */
>
> This behavior isn't obvious, so it should be mentioned in the docstring
> of "defvar" and in
>
> (info "(elisp) Defining Variables")
How about this:
>From c284028ba554fb4292d3a3ef275351d5f2dda80e Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Sat, 10 Feb 2018 14:06:05 -0500
Subject: [PATCH] Explain more about (defvar foo) form (Bug#18059)
* doc/lispref/variables.texi (Defining Variables):
* doc/lispref/compile.texi (Compiler Errors): Emphasize that omitting
VALUE for `defvar' marks the variable special only locally.
---
doc/lispref/compile.texi | 4 ++--
doc/lispref/variables.texi | 10 +++++++---
2 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/doc/lispref/compile.texi b/doc/lispref/compile.texi
index 0e39866d34..77d35be1ba 100644
--- a/doc/lispref/compile.texi
+++ b/doc/lispref/compile.texi
@@ -500,8 +500,8 @@ Compiler Errors
@item
Likewise, you can tell the compiler that a variable is defined using
@code{defvar} with no initial value. (Note that this marks the
-variable as special, i.e.@: dynamically bound.) @xref{Defining
-Variables}.
+variable as special, i.e.@: dynamically bound, but only within the
+file.) @xref{Defining Variables}.
@end itemize
You can also suppress any and all compiler warnings within a certain
diff --git a/doc/lispref/variables.texi b/doc/lispref/variables.texi
index e025d3fd10..cd9e1afc97 100644
--- a/doc/lispref/variables.texi
+++ b/doc/lispref/variables.texi
@@ -442,9 +442,13 @@ Defining Variables
evaluated and @var{symbol} is set to the result. But if @var{symbol}
is not void, @var{value} is not evaluated, and @var{symbol}'s value is
left unchanged. If @var{value} is omitted, the value of @var{symbol}
-is not changed in any case. Using @code{defvar} with no value is one
-method of suppressing byte compilation warnings, see @ref{Compiler
-Errors}.
+is not changed in any case.
+
+Note that specifying a value, even @code{nil}, marks the variable as
+special permanently. Whereas if @var{value} is omitted then the
+variable is only marked special locally (i.e. within the current file
+or let-block). This can be useful for suppressing byte compilation
+warnings, see @ref{Compiler Errors}.
If @var{symbol} has a buffer-local binding in the current buffer,
@code{defvar} acts on the default value, which is buffer-independent,
--
2.11.0
- bug#18059: 24.3.92; defvar and special variables,
Noam Postavsky <=
- bug#18059: 24.3.92; defvar and special variables, Michael Heerdegen, 2018/02/10
- bug#18059: 24.3.92; defvar and special variables, Drew Adams, 2018/02/10
- bug#18059: 24.3.92; defvar and special variables, Noam Postavsky, 2018/02/10
- bug#18059: 24.3.92; defvar and special variables, Stefan Monnier, 2018/02/11
- bug#18059: 24.3.92; defvar and special variables, Noam Postavsky, 2018/02/11
- bug#18059: 24.3.92; defvar and special variables, Michael Heerdegen, 2018/02/11
- bug#18059: 24.3.92; defvar and special variables, Noam Postavsky, 2018/02/11