Extensions

- Created scripts/extensions/README to describe samples.
- Created sample extension scripts of each type.

scripts/extensions/uda.lua

@@ -0,0 +1,61 @@
+-- User Defined Attribute Extension.
+-- Implementing 'priority'.
+
+-- Arguments: None
+-- Returns:   An 8-element list of installation details.  Only called once, on
+--            installation of the extension.
+function install ()
+  return 'uda',                            -- Type
+         'priority',                       -- Name
+         1.0,                              -- Version
+         'Implements priority attribute',  -- Description
+         'Paul Beckingham',                -- Author
+         'paul@beckingham.net',            -- Contact
+         'GPLv2',                          -- License
+         '© 2011, Göteborg Bit Factory'    -- Copyright
+end
+
+
+-- Arguments: None
+-- Returns:   Data type
+function type ()
+  return 'custom'
+end
+
+-- Arguments: proposed value
+-- Returns:   1 --> allowed
+--            0 --> disallowed
+function allowed (value)
+  if value == 'H' ||
+     value == 'M' ||
+     value == 'L' ||
+     value == '' then
+    return 1
+  end
+
+  return 0
+end
+
+-- Arguments: left and right values to compare
+-- Returns:   1 --> left < right
+--            0 --> left >= right
+function compare (left, right)
+  if left == 'M' && right == 'H' then
+    return 1
+  elseif left == 'L' && (right == 'H' || right == 'M') then
+    return 1
+  elseif left == '' then
+    return 1
+  end
+
+  return 0
+end
+
+-- Arguments: Raw data
+-- Returns:   Formatted data
+-- Note:      Shown here is a pass-through format, doing no formatting.  This is
+--            the default behavior if the format function is not implemented.
+function format (value)
+  return value
+end
+