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General Sparse Table
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Sometimes when working with tables there is a natural value to use as
the entry in all but a few cases.  The GeneralSparseTable constructor
can be used to provide any table type with a default value for
entries.

Suppose we launched a fund-raising campaign to raise fifty thousand
dollars.  To record the contributions, we want a table with strings as
keys (for the names) and integer entries (for the amount).  In a data
base of cash contributions, unless someone has been explicitly
entered, it is reasonable to assume they have made a zero dollar
contribution.

This creates a keyed access file with default entry 0. ::

  patrons: GeneralSparseTable(String, Integer, KeyedAccessFile(Integer), 0) := table() ; 

Now patrons can be used just as any other table.  Here we record two gifts. ::

  patrons."Smith" := 10500 

  patrons."Jones" := 22000

Now let us look up the size of the contributions from Jones and Stingy. ::

  patrons."Jones" 

  patrons."Stingy"

Have we met our seventy thousand dollar goal? ::

  reduce(+, entries patrons) 

So the project is cancelled and we can delete the data base: ::

  )system rm -r kaf*.sdata

See Also:

* ``)show GeneralSparseTable``