= A proposal to implement named styles and labels in MapServer =

== Proposed Map File Syntax Example ==

{{{
MAP
  STYLE
    # define a named style with global visibility
    NAME "some_style"
    ...
  END
  ...
  LAYER
    NAME "uses_a_style"
    CLASS
       # a name instead of a block means 'use the named style directly'
       STYLE "some_style"
       ...
    END
  END
  LAYER 
    NAME "extends_a_style"
    CLASS
      STYLE
        # inside a style block, pull in properties from another style
        # then make custom changes for this LAYER/CLASS
        EXTENDS "some_style"
        ...
      END
    END
  END
END
}}}

== Mapfile Extensions ==

 * Enable `STYLE` blocks at the top `MAP` level
   * Add a `NAME` directive to the `STYLE` block
   * Top-level `STYLE` blocks ''must'' be named

 * Provide a "named style" declaration in the `LAYER` block in the form of `LAYER "name"` (in addition to the existing `LAYER ... END` syntax)
   * The `LAYER` object gets instantiated with a ''copy'' of the named style from the top level
   * Referencing a non-existent `STYLE` by name throws an exception

 * Add an `EXTENDS "style"` directive to the `STYLE` block
   * Block styles that inherit from a named style are instantied as a copy of the named style before other declarations in the `STYLE` block are applied

== MapServer `StyleObj` Extensions ==

 * Add a "name" property to styleObj
 * Add a "shared" property to styleObj
   * Exporting a map file would emit all styleObjs with style.shared set to true at the top level
   * Programmatic changes to shared styles *would* affect all classes using that style
   * If you don't want that behavior, use cloneStyle/EXTENDS
 * Add a "cloneStyle" function to mapfile.c
   * This would be the programmatic interface for `EXTENDS`
   * cloneStyle would presumably copy a top-level style and set the new object's `shared` property to false
 * Look at INLINESYMBOLS(?) for exporting styles

== MapScript Extensions ==

 * ...?
 *