This commit makes the formatted values' main constructors `const`,
so that they can be used in constant definitions.
`from_usize` constructors can't be made const because `try_into`
can't be used in `const` functions as of rustc 1.64.0. Same for
`Percent::from_ratio`: floating point arithmetic is not allowed.
Introduce a set of Constructor traits which are implemented on
integer of float depending on the formatted values. This traits
allows building formatted values using expressions such as:
```rust
let buffer_nb = 20.buffers();
let size = 42.k_bytes();
let duration = 15.minutes() + 30.seconds();
let quantity = 42.default_format();
let progress = 20.percent();
let progress = 0.2.percent_ratio();
```
Previous proposition for constructing specific formatted values was
to use an operation such as `42 * Default::ONE` which, in retrospect,
doesn't seem idiomatic.
This commit adds `from_u64` and `from_usize` constructors for most
formatted values. Having `from_usize` is convenient when dealing with
quantities related to containers indices or length.
This also fixes the `Percent` from float constructors from which was
derived the `ONE` constant as well as previous display implementation.
Also removed the `pub` specifier for `Undefined` inner value. It wasn't
removed in a previous commit as `Undefined` can use the full range of
the inner type. But now, it seems preferable not to expose the inner
value for proper encapsulation and so as to reduce the differences with
other formatted values (kind of least astonishment principle).
... users would be able to bypass the range checks and build a
defined Rust value which would be interpreted as `None` in C code.
Added format module examples for formatted values constructions.
- The `GST_FORMAT_PERCENT_SCALE` was not used to compute the value
to display.
- Added `Display` examples in the format module documentation.
- Simplified `glib_newtype_display` macro.
The `Signed` version for `GenericFormattedValue` was implemented as
`Signed<GenericFormattedValue>`, which failed to represent properly
the `None` variants when applicable and could represent inconsistent
`Signed` variant combined with `GenericFormattedValue` formats which
are internaly represented as signed integers.
Some operations were implemented on types that wouldn't result in
the expected physical unit. E.g.:
- `ClockTime / ClockTime` results in a unit-less factor.
- `u64 / ClockTime` would result in a `1 / ClockTime`. Since we don't
use any `Frequency` type, this operation is removed. Users should
use the `ClockTime` accessors to compute the expected value.
This commit also adds:
- multiplications with integers as the left hand side operands.
- `Partial{Eq,Ord} for `Signed<T>` with `T` as left hand side operand.
- `opt_add` / `opt_sub` for `Signed<T>` with `T` as left or right hand
side operands.
- missing tests for `Partial{Eq,Ord}` and `OptionOrd`.
This implementation can interfere with unrelated code and was removed:
- `Signed<usize>.` `PartialOrd` makes existing code computing the len
of slices needing type annotation because the len is later used in
a comparison for which the compiler is unable to determine if
the len is `Signed<usize>` or `usize`.
