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Rename to if-let* and when-let*

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Make the existing if-let and when-let aliases.
* lisp/emacs-lisp/subr-x.el (if-let*, when-let*): New macros.  Rewrite
docstrings, incorporating that from let* and the existing if-let.
(if-let, when-let, and-let*): Alias them.
This commit is contained in:
Mark Oteiza 2017-02-03 21:42:42 -05:00
parent e080d019f4
commit be10c00d3d
2 changed files with 28 additions and 12 deletions
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36
lisp/emacs-lisp/subr-x.el
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@ -115,12 +115,16 @@ threading."
binding))
bindings)))
(defmacro if-let (bindings then &rest else)
"Process BINDINGS and if all values are non-nil eval THEN, else ELSE.
Argument BINDINGS is a list of tuples whose car is a symbol to be
bound and (optionally) used in THEN, and its cadr is a sexp to be
evalled to set symbol's value. In the special case you only want
to bind a single value, BINDINGS can just be a plain tuple."
(defmacro if-let* (bindings then &rest else)
"Bind variables according to VARLIST and eval THEN or ELSE.
Each binding is evaluated in turn with `let*', and evaluation
stops if a binding value is nil. If all are non-nil, the value
of THEN is returned, or the last form in ELSE is returned.
Each element of VARLIST is a symbol (which is bound to nil)
or a list (SYMBOL VALUEFORM) (which binds SYMBOL to the value of VALUEFORM).
In the special case you only want to bind a single value,
VARLIST can just be a plain tuple.
\n(fn VARLIST THEN ELSE...)"
(declare (indent 2)
(debug ([&or (&rest (symbolp form)) (symbolp form)] form body)))
(when (and (<= (length bindings) 2)
@ -132,15 +136,23 @@ to bind a single value, BINDINGS can just be a plain tuple."
,then
,@else)))
(defmacro when-let (bindings &rest body)
"Process BINDINGS and if all values are non-nil eval BODY.
Argument BINDINGS is a list of tuples whose car is a symbol to be
bound and (optionally) used in BODY, and its cadr is a sexp to be
evalled to set symbol's value. In the special case you only want
to bind a single value, BINDINGS can just be a plain tuple."
(defmacro when-let* (bindings &rest body)
"Bind variables according to VARLIST and conditionally eval BODY.
Each binding is evaluated in turn with `let*', and evaluation
stops if a binding value is nil. If all are non-nil, the value
of the last form in BODY is returned.
Each element of VARLIST is a symbol (which is bound to nil)
or a list (SYMBOL VALUEFORM) (which binds SYMBOL to the value of VALUEFORM).
In the special case you only want to bind a single value,
VARLIST can just be a plain tuple.
\n(fn VARLIST BODY...)"
(declare (indent 1) (debug if-let))
(list 'if-let bindings (macroexp-progn body)))
(defalias 'if-let 'if-let*)
(defalias 'when-let 'when-let*)
(defalias 'and-let* 'when-let*)
(defsubst hash-table-empty-p (hash-table)
"Check whether HASH-TABLE is empty (has 0 elements)."
(zerop (hash-table-count hash-table)))