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Diffstat (limited to 'module/srfi/srfi-39.scm')
-rw-r--r-- | module/srfi/srfi-39.scm | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/module/srfi/srfi-39.scm b/module/srfi/srfi-39.scm new file mode 100644 index 000000000..661ab0fbe --- /dev/null +++ b/module/srfi/srfi-39.scm @@ -0,0 +1,55 @@ +;;; srfi-39.scm --- Parameter objects + +;; Copyright (C) 2004, 2005, 2006, 2008, 2011 Free Software Foundation, Inc. +;; +;; This library is free software; you can redistribute it and/or +;; modify it under the terms of the GNU Lesser General Public +;; License as published by the Free Software Foundation; either +;; version 3 of the License, or (at your option) any later version. +;; +;; This library 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 +;; Lesser General Public License for more details. +;; +;; You should have received a copy of the GNU Lesser General Public +;; License along with this library; if not, write to the Free Software +;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + +;;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org> +;;; Date: 2004-05-05 + +;;; Commentary: + +;; This is an implementation of SRFI-39 (Parameter objects). +;; +;; The implementation is based on Guile's fluid objects, and is, therefore, +;; thread-safe (parameters are thread-local). +;; +;; In addition to the forms defined in SRFI-39 (`make-parameter', +;; `parameterize'), a new procedure `with-parameters*' is provided. +;; This procedures is analogous to `with-fluids*' but taking as first +;; argument a list of parameter objects instead of a list of fluids. +;; + +;;; Code: + +(define-module (srfi srfi-39) + ;; helper procedure not in srfi-39. + #:export (with-parameters*) + #:re-export (make-parameter + parameterize + current-input-port current-output-port current-error-port)) + +(cond-expand-provide (current-module) '(srfi-39)) + +(define (with-parameters* params values thunk) + (let more ((params params) + (values values) + (fluids '()) ;; fluids from each of PARAMS + (convs '())) ;; VALUES with conversion proc applied + (if (null? params) + (with-fluids* fluids convs thunk) + (more (cdr params) (cdr values) + (cons (parameter-fluid (car params)) fluids) + (cons ((parameter-converter (car params)) (car values)) convs))))) |