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Re: UnaryFns & Tables
- To: <mark>, <tribble>
- Subject: Re: UnaryFns & Tables
- From: Hugh Hoover <heh>
- Date: Sat, 28 Oct 89 15:23:06 PDT
- Cc: <xanatech>
I essentially agree with Dean on this one. Having both UnaryFns and
TableViews is a good solution because they have different purposes, even
if the mechanics are similar.
I'm implementing TableViews in the same manner that UnaryFns are implemented,
in that you must instantiate a derived class of TableView to get a useful
mapping. I've created 2 standard mappings already, called IndexMappedTable
and FunctionMappedTabled. IndexMapped applies a UnaryFn (provided during
construction) to the key before doing a fetch on a hidden table (also provided
during construction). FunctionMapped, on the other hand, performs the fetch
first, and applies a UnaryFn to the result.
Since new TableViews can be built easily, getting one to perform wierd and
strange things only costs writing a new class. It IS possible to write
essentially a UnaryFn (with no hidden table), but it probably isn't useful
in most cases.
Let's consider this thread closed, shall we?