Clemson University -- CPSC 231 -- Fall 2009


binding - assignment of name, value, or other attribute to an object

                       object
        +------+      .-----.
        | name |---->< value >    the name can be symbolic, binary address, ...
        +------+      `-----'     the value can be text, binary value, ...

  naming
    - resolution: what size unit is assigned a name - bit, byte, word, block?
    - range: how many different objects can you name?
    - order: binary numbers are ordered, add offset to one to construct another
    - dimensionality: true segmentation uses two-dimensional names
    - homogeneity: array name is name of collection of homogeneous data, while
        struct/record name is name of collection of heterogeneous data
    - context-dependent name: abbreviated name must use some form of context
        to disambiguate (that is, to resolve the name among multiple objects)
        (note: context search rules called "scoping")
    - aliases: multiple names for same object
    - protection: do you associate access rights with names or with objects?
        (e.g., consider file system)

  binding type
    static binding - done once
    dynamic binding - done several times (dynamic binding of names usually
      requires a naming table)

  binding time - when done - e.g., compile time, run time
    early binding
    late binding, sometimes called lazy evaluation - done only when needed
      (e.g., "just-in-time" compiler)

  static, early binding - e.g., compile-time binding in a strongly-typed
    language, catch errors early, can execute efficiently
  dynamic, late binding - e.g., run-time binding in an interpretative
    language, flexible, easier to debug, but often slow

                  static binding          dynamic binding
                +-----------------------+-----------------------+
  assemble time | symbol name to address|                       |
                +-----------------------+-----------------------+
  link time     | external addr. resol. |                       |
                | relocation            |                       |
                +-----------------------+-----------------------+
  load time     | relocation            |                       |
                +-----------------------+-----------------------+
  run time      | "dynamic" linking     | value to mem location |\ dynamic
   (can be sub- | - is really a misnomer| parameter passing     || assignment
   divided, e.g.|   since binding done  | I/O buffers           |/ of value
   procedure-   |   at run time on first|                       |
   entry time)  |   call - this is lazy | choosing ISR (through |\
                |   evaluation          |   int. vect. table)   || dynamic
                |                       | segmentation/paging   || naming
                |                       |   (thru seg/pg table) || (separate
                |                       | file system directory || name table)
                |                       | file index nodes      |/
                |                       |                       |
                |                       | linked list with dyn. |\ name table
                |                       |   memory allocation   |/ is in links
                +-----------------------+-----------------------+