* Prelim

Run this code first:

#+begin_src emacs-lisp
  (require 'cl-lib)
  (defun awe-show-headers (&rest headers)
    (pp-to-string (save-excursion
                    (goto-char org-babel-current-src-block-location)
                    (cl-delete-if-not
                     (lambda (pair) (memq (car pair) headers))
                     (nth 2 (org-babel-get-src-block-info 'light))))))
#+end_src

#+RESULTS:
: awe-show-headers

* Case 1
** The old way
  :PROPERTIES:
  :cache:    foo
  :comments: bar
  :END:

#+begin_src emacs-lisp
(awe-show-headers :cache :comments)
#+end_src

#+RESULTS:
: ((:comments . "bar yes")
:  (:cache . "foo no"))

*** Subtree
    :PROPERTIES:
    :cache:    quux
    :END:

*Good*: we can inherit different header args from multiple levels in the hierarchy.

#+begin_src emacs-lisp
(awe-show-headers :cache :comments)
#+end_src

#+RESULTS:
: ((:comments . "bar yes")
:  (:cache . "quux no"))

** The new way
   :PROPERTIES:
   :header-args: :cache foo :comments bar
   :END:

#+begin_src emacs-lisp
(awe-show-headers :cache :comments)
#+end_src

#+RESULTS:
: ((:comments . "bar yes")
:  (:cache . "foo no"))

*** Subtree
    :PROPERTIES:
    :header-args: :cache quux
    :END:

*PROBLEM*: we don’t get =:comments foo= from parent headline (“The new way”)

#+begin_src emacs-lisp
(awe-show-headers :cache :comments)
#+end_src

#+RESULTS:
: ((:comments . "yes")
:  (:cache . "quux no"))

*** Subtree 2
    :PROPERTIES:
    :header-args+: :cache quux
    :END:

*PROBLEM*: we still don’t get =:comments foo= from parent headline even by using the +

#+begin_src emacs-lisp
(awe-show-headers :cache :comments)
#+end_src

#+RESULTS:
: ((:comments . "yes")
:  (:cache . "quux no"))

* Case 2

** old way

*** subtree
   :PROPERTIES:
   :var:    awe-x=1
   :END:

#+name: call-me
#+begin_src emacs-lisp
(or (and (boundp 'awe-x) awe-x) "drat")
#+end_src

*** other subtree

*Good*: the variable is bound from the site of definition, not call.

#+call: call-me()

#+RESULTS:
: 1


** new way

*** subtree
   :PROPERTIES:
   :header-args: :var awe-x=1
   :END:

#+name: call-me-new
#+begin_src emacs-lisp
(or (and (boundp 'awe-x) awe-x) "drat")
#+end_src

*** other subtree

*Bad*: the variable doesn’t get bound

#+call: call-me-new()

#+RESULTS:
: drat