procyberian/emacs
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Improved eval documentation

Browse source 
Prompted by Michael Heerdegen.

* src/eval.c (Feval):
* doc/lispref/eval.texi (Eval):
Be more precise about the LEXICAL argument.
This commit is contained in:
Mattias Engdegård 2023-10-23 11:12:33 +02:00
parent d1fa9f1956
commit 48e7f5493e
2 changed files with 12 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
doc/lispref/eval.texi
View file

@ -740,16 +740,17 @@ type of the @var{form} object determines how it is evaluated.
@xref{Forms}.
The argument @var{lexical} specifies the scoping rule for local
variables (@pxref{Variable Scoping}). If it is omitted or @code{nil},
that means to evaluate @var{form} using the default dynamic scoping
rule. If it is @code{t}, that means to use the lexical scoping rule.
variables (@pxref{Variable Scoping}). If it is @code{t}, that means
to evaluate @var{form} using lexical scoping; this is the recommended
value. If it is omitted or @code{nil}, that means to use the old
dynamic-only variable scoping rule.
The value of @var{lexical} can also be a non-empty list specifying a
particular @dfn{lexical environment} for lexical bindings; however,
this feature is only useful for specialized purposes, such as in Emacs
Lisp debuggers. Each member of the list is either a cons cell which
represents a lexical symbol-value pair, or a symbol representing a
dynamically bound variable.
(special) variable that would use dynamic scoping if bound.
Since @code{eval} is a function, the argument expression that appears
in a call to @code{eval} is evaluated twice: once as preparation before

10
src/eval.c
View file

@ -2364,9 +2364,13 @@ static Lisp_Object list_of_t; /* Never-modified constant containing (t). */
DEFUN ("eval", Feval, Seval, 1, 2, 0,
doc: /* Evaluate FORM and return its value.
If LEXICAL is t, evaluate using lexical scoping.
LEXICAL can also be an actual lexical environment, in the form of an
alist mapping symbols to their value. */)
If LEXICAL is `t', evaluate using lexical binding by default.
This is the recommended value.
If absent or `nil', use dynamic scoping only.
LEXICAL can also represent an actual lexical environment; see the Info
node `(elisp)Eval' for details. */)
(Lisp_Object form, Lisp_Object lexical)
{
specpdl_ref count = SPECPDL_INDEX ();