Hello, :var header arguments can be provided multiple times. This is supported directly at the source block and through the default header argument facility. However, this was not handled correctly when the var was evaluated from a closure in a default header argument (only the last var was taken). This patch fixes that. I've also added documentation explaining how to set multiple vars in the default header argument facility.
Thanks, Matt
>From 5f02fe4e896e6909fab18e8d90a7e14bdce9d5c4 Mon Sep 17 00:00:00 2001 From: Matt Huszagh <huszaghm...@gmail.com> Date: Wed, 27 Oct 2021 07:47:20 -0700 Subject: [PATCH] ob-core.el: Fix behavior of lambda default header arg vars * lisp/ob-core.el: Permit multiple :var default header arguments when using closures. Additionally, document how to use default header arguments for arguments that can be provided multiple times. --- lisp/ob-core.el | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) diff --git a/lisp/ob-core.el b/lisp/ob-core.el index 7a9467b0e..21f461a08 100644 --- a/lisp/ob-core.el +++ b/lisp/ob-core.el @@ -478,12 +478,21 @@ For the format of SAFE-LIST, see `org-babel-safe-header-args'." 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))). +evaluates to a string. Some header arguments (e.g., :var for +some language backends) can be provided multiple times for a +source block. This functionality is also supported for default +header arguments by providing the header argument multiple times +in the alist. For example: + +'((:var . \"foo=\\\"bar\\\"\") + (:var . \"bar=\\\"foo\\\"\")) + +A 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 @@ -2718,6 +2727,11 @@ parameters when merging lists." (pcase pair (`(:var . ,value) (let ((name (cond + ;; Default header arguments can accept lambda + ;; functions. We uniquely identify the var + ;; according to the full string contents of + ;; the lambda function. + ((functionp value) value) ((listp value) (car value)) ((string-match "^\\([^= \f\t\n\r\v]+\\)[ \t]*=" value) (intern (match-string 1 value))) -- 2.31.1
