diff options
Diffstat (limited to 'lisp/emacs-lisp/subr-x.el')
| -rw-r--r-- | lisp/emacs-lisp/subr-x.el | 41 |
1 files changed, 29 insertions, 12 deletions
diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el index 7736225b5fa..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))) @@ -214,6 +226,11 @@ user enters `recenter', `scroll-up', or `scroll-down' responses, perform the requested window recentering or scrolling and ask again. +When `use-dialog-box' is t (the default), this function can pop +up a dialog window to collect the user input. That functionality +requires `display-popup-menus-p' to return t. Otherwise, a text +dialog will be used. + The return value is the matching entry from the CHOICES list. Usage example: |