18.5. Other Examples of Table Lookups

A few other examples of table lookups appear in other sections of the book. They're used in the course of discussing other techniques, and the contexts don't emphasize the table lookups per se. Here's where you'll find them:

• Looking up rates in an insurance table: Section 16.3, "Creating Loops Easily From the Inside Out"

• Using decision tables to replace complicated logic: "Use decision tables to replace complicated conditions" in Section 19.1.

• Cost of memory paging during a table lookup: Section 25.3, "Kinds of Fat and Molasses"

• Combinations of boolean values (A or B or C): "Substitute Table Lookups for Complicated Expressions" in Section 26.1

• Precomputing values in a loan repayment table: Section 26.4, "Expressions."

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Checklist: Table-Driven Methods

• Have you considered table-driven methods as an alternative to complicated logic?

• Have you considered table-driven methods as an alternative to complicated inheritance structures?

• Have you considered storing the table's data externally and reading it at run time so that the data can be modified without changing code?

• If the table cannot be accessed directly via a straightforward array index (as in the age example), have you put the access-key calculation into a routine rather than duplicating the index calculation in the code?