Closure operator now behaves as default argument operator, documentation.

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@965 0fc631ac-6414-0410-93d0-97cfa31319b6

doc/script/variables.txt

@@ -74,4 +74,17 @@ This can be done by first making a copy, and calling that:
 > to_upper("xyz") == "upper case: XYZ"
 Note that @real_to_upper@ is called without extra parameters, the @input@ variable is still set from the outer call to the new @to_upper@ itself.
 
+--Default arguments--
+It is possible to declare default arguments for functions using the @@@@ operator.
+> function := { "argument was: " + arg }@(arg:"default")
+If this function is called without the @arg@ argument, then the default value @default@ is used instead.
+For example:
+> function()                      == "argument was: default"
+> function(arg: "something else") == "argument was: something else"
+For determining whether the argument is set only explicit arguments count, not everything in scope, so
+> arg := "something else"
+> function()                      == "argument was: default"
+
+Defaults are evaluated at the time the @@@@ operator is evaluated, so they can be used to simulate static scoping.
+
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