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Design doc updated with a derived unit short name

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Mateusz Pusz
2019-10-15 11:42:06 +02:00
parent b889c81cb9
commit 98b78c9a2c
1 changed files with 19 additions and 19 deletions
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38
doc/DESIGN.md
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@@ -242,14 +242,14 @@ struct unit : downcast_base<unit<D, R>> {
All units are created with a `derived_unit` helper: All units are created with a `derived_unit` helper:
```cpp ```cpp
template<typename Child, typename...> template<typename Child, fixed_string Name, typename...>
struct derived_unit; struct derived_unit;
``` ```
For example to define the base unit of `length`: For example to define the base unit of `length`:
```cpp ```cpp
struct metre : derived_unit<metre, length> {}; struct metre : derived_unit<metre, "m", length> {};
``` ```
Again, similarly to `derived_dimension`, the first class template parameter is a CRTP idiom used Again, similarly to `derived_dimension`, the first class template parameter is a CRTP idiom used
@@ -259,46 +259,46 @@ to provide downcasting facility (described below).
- helper to create a base unit of a specified dimension - helper to create a base unit of a specified dimension
```cpp ```cpp
template<typename Child, Dimension D> template<typename Child, fixed_string Name, Dimension D>
struct derived_unit<Child, D>; struct derived_unit<Child, Name, D>;
``` ```
```cpp ```cpp
struct metre : derived_unit<metre, length> {}; struct metre : derived_unit<metre, "m", length> {};
``` ```
- helper to create other units for a specified dimension - helper to create other units for a specified dimension
```cpp ```cpp
template<typename Child, Dimension D, Ratio R> template<typename Child, fixed_string Name, Dimension D, Ratio R>
struct derived_unit<Child, D, R>; struct derived_unit<Child, Name, D, R>;
``` ```
```cpp ```cpp
struct yard : derived_unit<yard, length, ratio<9'144, 10'000>> {}; struct yard : derived_unit<yard, "yd", length, ratio<9'144, 10'000>> {};
``` ```
- helper to create a unit with a SI prefix - helper to create a unit with a SI prefix
```cpp ```cpp
template<typename Child, Unit U> template<typename Child, fixed_string Name, Unit U>
struct derived_unit<Child, U>; struct derived_unit<Child, Name, U>;
``` ```
```cpp ```cpp
struct kilometre : derived_unit<kilometre, kilo<metre>> {}; struct kilometre : derived_unit<kilometre, "km", kilo<metre>> {};
``` ```
- helper that automatically calculates ratio based on info in desired dimension and provided list - helper that automatically calculates ratio based on info in desired dimension and provided list
of units of base dimensions of units of base dimensions
```cpp ```cpp
template<typename Child, Dimension D, Unit U, Unit... Us> template<typename Child, fixed_string Name, Dimension D, Unit U, Unit... Us>
struct derived_unit<Child, D, U, Us...>; struct derived_unit<Child, Name, D, U, Us...>;
``` ```
```cpp ```cpp
struct kilometre_per_hour : derived_unit<kilometre_per_hour, velocity, kilometre, hour> {}; struct kilometre_per_hour : derived_unit<kilometre_per_hour, "km/h", velocity, kilometre, hour> {};
``` ```
`units::Unit` is a concept that is satisfied by a type that is empty and publicly `units::Unit` is a concept that is satisfied by a type that is empty and publicly
@@ -554,8 +554,8 @@ struct derived_dimension : downcast_helper<Child, detail::make_dimension_t<Es...
``` ```
```cpp ```cpp
template<typename Child, Dimension D> template<typename Child, fixed_string Name, Dimension D>
struct derived_unit<Child, D, R> : downcast_helper<Child, unit<D, ratio<1>>> {}; struct derived_unit<Child, Name, D, R> : downcast_helper<Child, unit<D, ratio<1>>> {};
``` ```
With such CRTP types the only thing the user has to do to register a new type to the downcasting With such CRTP types the only thing the user has to do to register a new type to the downcasting
@@ -563,7 +563,7 @@ facility is to publicly derive from one of those CRTP types and provide its new
the first template parameter of the CRTP type. the first template parameter of the CRTP type.
```cpp ```cpp
struct metre : derived_unit<metre, length> {}; struct metre : derived_unit<metre, "m", length> {};
``` ```
Above types are used to define base and target of a downcasting operation. To perform the actual Above types are used to define base and target of a downcasting operation. To perform the actual
@@ -644,8 +644,8 @@ In order to extend the library with custom dimensions the user has to:
4. Define units and register them to a downcasting facility: 4. Define units and register them to a downcasting facility:
```cpp ```cpp
struct bit : units::derived_unit<bit, digital_information> {}; struct bit : units::derived_unit<bit, "b", digital_information> {};
struct byte : units::derived_unit<byte, digital_information, units::ratio<8>> {}; struct byte : units::derived_unit<byte, "B", digital_information, units::ratio<8>> {};
``` ```
5. Provide user-defined literals for the most important units: 5. Provide user-defined literals for the most important units: