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83 lines
2.8 KiB
Markdown
83 lines
2.8 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/Troolean/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/Troolean/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/Troolean/blob/master/LICENSE)
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[](https://github.com/RobTillaart/Troolean/releases)
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# Troolean
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Arduino Library for a three state logic data type supporting {True False Unknown}.
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## Description
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Troolean is a data type that implements three state logic with the values
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{True False Unknown }
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Logic operators are similar to boolean and behave the same for the familiar boolean values.
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Trooleans can be used e.g. to indicate a value is valid, invalid or unknown to be valid or not.
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Imagine a monitoring application which has different sensors e.g. temperature.
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If the sensor is sampled less than 1 minute ago one could say the value is valid.
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If the last sample is taken more than an hour ago it could have changed (a lot) or not.
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So one does not know if the temperature has become invalid or not.
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Boolean logic would make it invalid, but troolean allows to state we just don't know.
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As long as there is no urgency (need a valid value) one does not need to resample yet.
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See also https://en.wikipedia.org/wiki/Three-valued_logic
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## Interface
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to elaborate.
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#### Constructor
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- **Troolean()** value is unknown.
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- **Troolean(const int8_t)** 0 = false, -1 = unknown anything else = true
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- **Troolean(const Troolean&)** copy constructor.
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#### Equality operators
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- **bool operator ==** equals
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- **bool operator !=** not equal
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- **operator bool()** convert to boolean.
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#### Logical operators
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- **Troolean operator ! ** negation, not UNKNOWN == UNKNOWN.
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- **Troolean operator && ** AND
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- **Troolean operator || ** OR
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#### Value operators
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- **bool isTrue()** if not false and if not unknown.
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- **bool isFalse()** idem.
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- **bool isUnknown()** idem.
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## Operation
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See examples
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## Future
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#### must
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- fix **isTrue()** to allow internal values to be anything except 0 and -1 (0.2.0)
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- check logical operators.
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- update documentation
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#### should
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- add unit tests (derive from test troolean.ino?)
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- add examples
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#### could
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- Troolean operator &&=
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- Troolean operator ||=
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- bool toBool(); // returns random true/false if unknown....
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#### wont
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- extend with don't care ? ==> four state logic ? Foolean?
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- => new class.
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