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| author | Stefan Monnier <monnier@iro.umontreal.ca> | 2018-10-30 14:24:31 -0400 |
|---|---|---|
| committer | Stefan Monnier <monnier@iro.umontreal.ca> | 2018-10-30 14:24:31 -0400 |
| commit | eb903d8f20ab0c31daa27a08b0acfd30115c7b5e (patch) | |
| tree | 72ef22d00690e7984c735fecd12e959d9a91e9c0 /lisp/emacs-lisp/pcase.el | |
| parent | 86abbb3cb8490f73eb00023cf1c9ea7b5a8fffaf (diff) | |
| download | emacs-eb903d8f20ab0c31daa27a08b0acfd30115c7b5e.tar.gz emacs-eb903d8f20ab0c31daa27a08b0acfd30115c7b5e.tar.bz2 emacs-eb903d8f20ab0c31daa27a08b0acfd30115c7b5e.zip | |
* lisp/emacs-lisp/pcase.el: Improve docstrings.
Diffstat (limited to 'lisp/emacs-lisp/pcase.el')
| -rw-r--r-- | lisp/emacs-lisp/pcase.el | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/lisp/emacs-lisp/pcase.el b/lisp/emacs-lisp/pcase.el index fa7b1de8b4d..2e89ae0779a 100644 --- a/lisp/emacs-lisp/pcase.el +++ b/lisp/emacs-lisp/pcase.el @@ -266,7 +266,8 @@ variable name being but a special case of it)." (defmacro pcase-let* (bindings &rest body) "Like `let*' but where you can use `pcase' patterns for bindings. BODY should be an expression, and BINDINGS should be a list of bindings -of the form (PAT EXP)." +of the form (PATTERN EXP). +See `pcase-let' for discussion of how PATTERN is matched." (declare (indent 1) (debug ((&rest (pcase-PAT &optional form)) body))) (let ((cached (gethash bindings pcase--memoize))) @@ -281,10 +282,11 @@ of the form (PAT EXP)." (defmacro pcase-let (bindings &rest body) "Like `let' but where you can use `pcase' patterns for bindings. BODY should be a list of expressions, and BINDINGS should be a list of bindings -of the form (PAT EXP). -The macro is expanded and optimized under the assumption that those -patterns *will* match, so a mismatch may go undetected or may cause -any kind of error." +of the form (PATTERN EXP). +The PATTERNs are only used to extract data, so the code does not test +whether the data does match the corresponding patterns: a mismatch +may signal an error or may go undetected, binding variables to arbitrary +values, such as nil." (declare (indent 1) (debug pcase-let*)) (if (null (cdr bindings)) `(pcase-let* ,bindings ,@body) @@ -302,7 +304,11 @@ any kind of error." ;;;###autoload (defmacro pcase-dolist (spec &rest body) - "Like `dolist' but where the binding can be a `pcase' pattern. + "Superset of `dolist' where the VAR binding can be a `pcase' PATTERN. +More specifically, this is just a shorthand for the following combination +of `dolist' and `pcase-let': + + (dolist (x LIST) (pcase-let ((PATTERN x)) BODY...)) \n(fn (PATTERN LIST) BODY...)" (declare (indent 1) (debug ((pcase-PAT form) body))) (if (pcase--trivial-upat-p (car spec)) |