Passing Variables to Source Blocks

In which I document ways to define variables in an org file, and use those variables in SRC blocks throughout the rest of the file.

Global header args

Define variables globally in an org file using #+PROPERTY. Notice that the values can be elisp expressions. values.

NOTE: when changing a variable defined with #+PROPERTY, the buffer needs to be reloaded to take effect. Use M-x revert-buffer to reload the buffer.

echo $globalVar1
echo $globalVar2
echo $globalVar3

#+RESULTS:

Global Var 1 Value
5
4

Elisp association list

Define an elisp association list (alist) that maps variable names to values, and a lookup function for looking up a variable's value by name.

'(("alistVar1" "Alist Var 1 Value", "Alist var 1 description")
  ("alistVar2" 7 "Alist var 2 description"))

(nth 1 (assoc v data))

echo $v1
echo $v2

#+RESULTS:

Alist Var 1 Value
7

Org table

Define an org table that maps variable names to values, and a lookup function for looking up a variable's value by name. Under the covers, the table is just an elisp alist.

Var Name	Value	Description
tableVar1	Table Var 1 Value	Table var 1 description
tableVar2	6	Table var 2 description

(nth 1 (assoc v data))

echo $v1
echo $v2

#+RESULTS:

Table Var 1 Value
6

Drawer header args

These variables apply to all source blogs within this section.

echo $drawerVar1
echo $drawerVar2

#+RESULTS:

Drawer Var 1
8

Drawer header args using table

Same as above, but look up variable values from a table (specifically, the table in section Org table).

NOTE Calling functions in header-args can be problematic because of a bug with org mode, described here.

echo $drawerTable1
echo $drawerTable2

#+RESULTS:

Table Var 1 Value
6