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author | Mark Oteiza <mvoteiza@udel.edu> | 2017-02-03 21:42:42 -0500 |
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committer | Mark Oteiza <mvoteiza@udel.edu> | 2017-02-03 21:42:42 -0500 |
commit | be10c00d3d64d53a7f31441d42f6c5b1f75b9916 (patch) | |
tree | f6398751a5f5d16e902f7d4b31e3912e550424f3 /lisp/emacs-lisp/subr-x.el | |
parent | e080d019f41d2738ba0db721c1b89ea57413439b (diff) | |
download | emacs-be10c00d3d64d53a7f31441d42f6c5b1f75b9916.tar.gz |
Rename to if-let* and when-let*
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.
Diffstat (limited to 'lisp/emacs-lisp/subr-x.el')
-rw-r--r-- | lisp/emacs-lisp/subr-x.el | 36 |
1 files changed, 24 insertions, 12 deletions
diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el index 52331b9ad36..f7a846927c0 100644 --- a/lisp/emacs-lisp/subr-x.el +++ b/lisp/emacs-lisp/subr-x.el @@ -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))) |