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[elpa] externals/org 9f1507b 4/5: ob-core.el: Add ability to use closure
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ELPA Syncer |
Subject: |
[elpa] externals/org 9f1507b 4/5: ob-core.el: Add ability to use closures as default header arguments |
Date: |
Wed, 29 Sep 2021 03:57:20 -0400 (EDT) |
branch: externals/org
commit 9f1507bdd1d3e902396bedab8318f30dac63df57
Author: Matt Huszagh <huszaghmatt@gmail.com>
Commit: Bastien <bzg@gnu.org>
ob-core.el: Add ability to use closures as default header arguments
* lisp/ob-core.el (org-babel-default-header-args): Document ability to
use closures.
(org-babel-eval-headers): New function to generate header arguments,
which adds the ability to evaluate closures during source block
execution or export.
(org-babel-merge-params): Only evaluate closures when we have our
final list of headers.
---
lisp/ob-core.el | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 55 insertions(+), 5 deletions(-)
diff --git a/lisp/ob-core.el b/lisp/ob-core.el
index c8380f7..bdc11d2 100644
--- a/lisp/ob-core.el
+++ b/lisp/ob-core.el
@@ -472,7 +472,35 @@ For the format of SAFE-LIST, see
`org-babel-safe-header-args'."
(defvar org-babel-default-header-args
'((:session . "none") (:results . "replace") (:exports . "code")
(:cache . "no") (:noweb . "no") (:hlines . "no") (:tangle . "no"))
- "Default arguments to use when evaluating a source block.")
+ "Default arguments to use when evaluating a source block.
+
+This is a list in which each element is an alist. Each key
+corresponds to a header argument, and each value to that header's
+value. The value can either be a string or a closure that
+evaluates to a string. The closure is evaluated when the source
+block is being evaluated (e.g. during execution or export), with
+point at the source block. It is not possible to use an
+arbitrary function symbol (e.g. 'some-func), since org uses
+lexical binding. To achieve the same functionality, call the
+function within a closure (e.g. (lambda () (some-func))).
+
+To understand how closures can be used as default header
+arguments, imagine you'd like to set the file name output of a
+latex source block to a sha1 of its contents. We could achieve
+this with:
+
+(defun org-src-sha ()
+ (let ((elem (org-element-at-point)))
+ (concat (sha1 (org-element-property :value elem)) \".svg\")))
+
+(setq org-babel-default-header-args:latex
+ `((:results . \"file link replace\")
+ (:file . (lambda () (org-src-sha)))))
+
+Because the closure is evaluated with point at the source block,
+the call to `org-element-at-point' above will always retrieve
+information about the current source block.")
+
(put 'org-babel-default-header-args 'safe-local-variable
(org-babel-header-args-safe-fn org-babel-safe-header-args))
@@ -583,6 +611,19 @@ the outer-most code block.")
(defvar *this*)
+(defun org-babel-eval-headers (headers)
+ "Compute header list set with HEADERS.
+
+Evaluate all header arguments set to functions prior to returning
+the list of header arguments."
+ (let ((lst nil))
+ (dolist (elem headers)
+ (if (and (cdr elem)
+ (functionp (cdr elem)))
+ (push `(,(car elem) . ,(funcall (cdr elem))) lst)
+ (push elem lst)))
+ lst))
+
(defun org-babel-get-src-block-info (&optional light datum)
"Extract information from a source block or inline source block.
@@ -2698,12 +2739,21 @@ parameters when merging lists."
results-exclusive-groups
results
(split-string
- (if (stringp value) value (eval value t))))))
+ (if (stringp value)
+ value
+ (if (functionp value)
+ (funcall value)
+ (eval value t)))))))
(`(:exports . ,value)
(setq exports (funcall merge
exports-exclusive-groups
exports
- (split-string (or value "")))))
+ (split-string (or
+ (if value
+ (if (functionp value)
+ (funcall value)
+ value)
+ ""))))))
;; Regular keywords: any value overwrites the previous one.
(_ (setq params (cons pair (assq-delete-all (car pair) params)))))))
;; Handle `:var' and clear out colnames and rownames for replaced
@@ -2718,14 +2768,14 @@ parameters when merging lists."
(cdr (assq param params))))
(setq params
(cl-remove-if (lambda (pair) (and (equal (car pair) param)
- (null (cdr pair))))
+ (null (cdr pair))))
params)))))
;; Handle other special keywords, which accept multiple values.
(setq params (nconc (list (cons :results (mapconcat #'identity results "
"))
(cons :exports (mapconcat #'identity exports "
")))
params))
;; Return merged params.
- params))
+ (org-babel-eval-headers params)))
(defun org-babel-noweb-p (params context)
"Check if PARAMS require expansion in CONTEXT.