From: phillip.lord@russet.org.uk (Phillip Lord)
To: Artur Malabarba <bruce.connor.am@gmail.com>
Cc: emacs-devel <emacs-devel@gnu.org>
Subject: Re: [ELPA] New package: validate.el
Date: Mon, 18 Apr 2016 15:17:19 +0100 [thread overview]
Message-ID: <8760vft30w.fsf@russet.org.uk> (raw)
In-Reply-To: <CAAdUY-KoV0QOyHO2Qkwjxyv9mQNgyULo+bun9us2MyiYURG0jg@mail.gmail.com> (Artur Malabarba's message of "Mon, 18 Apr 2016 03:42:41 -0300")
I've wanted something like this for years, so this is really nice.
Can I suggest something like:
(validate-setq cider-known-endpoints "whoops")
which errors or setq's as appropriate.
Phil
Artur Malabarba <bruce.connor.am@gmail.com> writes:
> I've written a package for validating values against custom-types,
> while providing useful messages when the validation fails.
> I'd like to add it to Elpa (hopefully I'm not reinventing the wheel here).
>
> Cheers,
> Artur
>
> ---
> ;;; validate.el --- Schema validation for Emacs-lisp -*-
> lexical-binding: t; -*-
>
> ;; Copyright (C) 2016 Artur Malabarba
>
> ;; Author: Artur Malabarba <emacs@endlessparentheses.com>
> ;; Keywords: lisp
> ;; Package-Requires: ((emacs "24.1") (cl-lib "0.5"))
> ;; Version: 0.1
>
> ;;; Commentary:
> ;;
> ;; This library offers two functions that perform schema validation.
> ;; Use this is your Elisp packages to provide very informative error
> ;; messages when your users accidentally misconfigure a variable.
> ;; For instance, if everything is fine, these do the same thing:
> ;;
> ;; 1. (validate-variable 'cider-known-endpoints)
> ;; 2. cider-known-endpoints
> ;;
> ;; However, if the user has misconfigured this variable, option
> ;; 1. will immediately give them an informative error message, while
> ;; option 2. won't say anything and will lead to confusing errors down
> ;; the line.
> ;;
> ;; The format and language of the schemas is the same one used in the
> ;; `:type' property of a `defcustom'.
> ;;
> ;; See: (info "(elisp) Customization Types")
> ;;
> ;; Both functions throw a `user-error' if the value in question
> ;; doesn't match the schema, and return the value itself if it
> ;; matches. The function `validate-variable' verifies whether the value of a
> ;; custom variable matches its custom-type, while `validate-value' checks an
> ;; arbitrary value against an arbitrary schema.
> ;;
> ;; Missing features: `:inline', `plist', `coding-system', `color',
> ;; `hook', `restricted-sexp'.
>
> ;;; License:
> ;;
> ;; This file is part of GNU Emacs.
> ;;
> ;; GNU Emacs is free software: you can redistribute it and/or modify
> ;; it under the terms of the GNU General Public License as published by
> ;; the Free Software Foundation, either version 3 of the License, or
> ;; (at your option) any later version.
> ;;
> ;; GNU Emacs is distributed in the hope that it will be useful,
> ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
> ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> ;; GNU General Public License for more details.
> ;;
> ;; You should have received a copy of the GNU General Public License
> ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
>
> ;;; Code:
> (require 'cl-lib)
> (require 'seq)
> (require 'cus-edit)
>
> (defun validate--check-list-contents (values schemas)
> "Check that all VALUES match all SCHEMAS."
> (if (not (= (length values) (length schemas)))
> "wrong number of elements"
> (seq-find #'identity (seq-mapn #'validate--check values schemas))))
>
> (defun validate--check (value schema)
> "Return nil if VALUE matches SCHEMA.
> If they don't match, return an explanation."
> (let ((args (cdr-safe schema))
> (expected-type (or (car-safe schema) schema))
> (props nil))
> (while (and (keywordp (car args)) (cdr args))
> (setq props `(,(pop args) ,(pop args) ,@props)))
> (setq args (or (plist-get props :args)
> args))
> (let ((r
> (cl-labels ((wtype ;wrong-type
> (tt) (unless (funcall (intern (format "%sp" tt)) value)
> (format "not a %s" tt))))
> ;; TODO: hook (top-level only).
> (cl-case expected-type
> ((sexp other) nil)
> (variable (cond ((wtype 'symbol))
> ((not (boundp value)) "this symbol has
> no variable binding")))
> ((integer number float string character symbol function
> boolean face)
> (wtype expected-type))
> (regexp (cond ((ignore-errors (string-match value "") t) nil)
> ((wtype 'string))
> (t "not a valid regexp")))
> (repeat (cond
> ((or (not args) (cdr args)) (error "`repeat'
> needs exactly one argument"))
> ((wtype 'list))
> (t (let ((subschema (car args)))
> (seq-some (lambda (v) (validate--check v
> subschema)) value)))))
> ((const function-item variable-item) (unless (eq value
> (car args))
> "not the expected value"))
> (file (cond ((wtype 'string))
> ((file-exists-p value) nil)
> ((plist-get props :must-match) "file does not exist")
> ((not (file-writable-p value)) "file is not
> accessible")))
> (directory (cond ((wtype 'string))
> ((file-directory-p value) nil)
> ((file-exists-p value) "path is not a
> directory")
> ((not (file-writable-p value))
> "directory is not accessible")))
> (key-sequence (and (wtype 'string)
> (wtype 'vector)))
> ;; TODO: `coding-system', `color'
> (coding-system (wtype 'symbol))
> (color (wtype 'string))
> (cons (or (wtype 'cons)
> (validate--check (car value) (car args))
> (validate--check (cdr value) (cadr args))))
> ((list group) (or (wtype 'list)
> (validate--check-list-contents value args)))
> (vector (or (wtype 'vector)
> (validate--check-list-contents value args)))
> (alist (let ((value-type (plist-get props :value-type))
> (key-type (plist-get props :key-type)))
> (cond ((not value-type) (error "`alist' needs
> a :value-type"))
> ((not key-type) (error "`alist' needs a
> :key-type"))
> ((wtype 'list))
> (t (validate--check value
> `(repeat (cons ,key-type
> ,value-type)))))))
> ;; TODO: `plist'
> ((choice radio) (if (not (cdr args))
> (error "`choice' needs at least one
> argument")
> (let ((gather (mapcar (lambda (x)
> (validate--check value x)) args)))
> (when (seq-every-p #'identity gather)
> (concat "all of the options failed\n "
> (mapconcat #'identity
> gather "\n "))))))
> ;; TODO: `restricted-sexp'
> (set (or (wtype 'list)
> (let ((failed (list t)))
> (dolist (schema args)
> (let ((elem (seq-find (lambda (x) (not
> (validate--check x schema)))
> value
> failed)))
> (unless (eq elem failed)
> (setq value (remove elem value)))))
> (when value
> (concat "the following values don't match
> any of the options:\n "
> (mapconcat (lambda (x) (format
> "%s" x)) value "\n "))))))))))
> (when r
> (let ((print-length 4)
> (print-level 2))
> (format "Looking for `%S' in `%S' failed because:\n%s"
> schema value r))))))
>
> ;;; Exposed API
> ;;;###autoload
> (defun validate-value (value schema &optional noerror)
> "Check that VALUE matches SCHEMA.
> If it matches return VALUE, otherwise signal a `user-error'.
>
> If NOERROR is non-nil, return t to indicate a match and nil to
> indicate a failure."
> (let ((report (validate--check value schema)))
> (if report
> (unless noerror
> (user-error report))
> value)))
>
> ;;;###autoload
> (defun validate-variable (symbol &optional noerror)
> "Check that SYMBOL's value matches its schema.
> SYMBOL must be the name of a custom option with a defined
> `custom-type'. If SYMBOL has a value and a type, they are checked
> with `validate-value'. NOERROR is passed to `validate-value'."
> (let* ((val (symbol-value symbol))
> (type (custom-variable-type symbol)))
> (if type
> (validate-value val type)
> (if noerror val
> (error "Variable `%s' has no custom-type." symbol)))))
>
> (provide 'validate)
> ;;; validate.el ends here
next prev parent reply other threads:[~2016-04-18 14:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-18 6:42 [ELPA] New package: validate.el Artur Malabarba
2016-04-18 12:30 ` Stefan Monnier
2016-04-18 15:10 ` Artur Malabarba
2016-04-18 14:17 ` Phillip Lord [this message]
2016-04-18 15:12 ` Artur Malabarba
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