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38 lines
1.4 KiB
Plaintext
38 lines
1.4 KiB
Plaintext
/** \page pricedocs Price Overview
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The Prices and the Price DB overview is in src/doc/design/engine.texinfo
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API: \ref Price
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Below, a few meta-notes about how prices and the GUI (should) interact:
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\section pricecompute Computing Prices
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When a price is computed from the (value/amt) that a user entered
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in a register, and this price is stored in the priceDB, then
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both the register entry and the price must have links to each other
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(via the KVP trees) so that each can be found from the other.
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This is needed because if the user enters an incorrect amt or value
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or date in the transaction register, and then corrects it later,
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possibly weeks or months later, the corresponding price in the
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priceDB must be fixed as well.
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Similarly, if a user deletes a transaction (possibly because it
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contains an error in date/amt/value), then it is advisable that
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the corresponding priceDB entry must be deleted as well (since
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it is not safe to assume that the price is 'correct').
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\section Rounding errors
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When doing price math in the register, one must be careful, because
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round-off errors can make 'obvious' math inaccurate. Note that if
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we define price as (value/amt), then we will find that
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value != price * amt due to roundoff handling. One must be careful
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and consistent in handling this in the register, as otherwise
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users will be driven crazy by inconsistent behaviour.
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(Linas Vepstas April 2003)
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*/
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