Trait kas::cast::ConvApprox
pub trait ConvApprox<T>: Sized {
// Required method
fn try_conv_approx(x: T) -> Result<Self, Error>;
// Provided method
fn conv_approx(x: T) -> Self { ... }
}Expand description
Like From, but for approximate numerical conversions
On success, the result must be approximately the same as the input value:
the difference must be smaller than the precision of the target type.
For example, one may have i32::conv_approx(1.9f32) = 1 or
f32::conv_approx(1f64 + (f32::EPSILON as f64) / 2.0) = 1.0.
Precise rounding mode should usually be truncation (round towards zero),
but this is not required. Use ConvFloat where a specific rounding mode
is required.
The sister-trait CastApprox supports “into” style usage.
Required Methods§
fn try_conv_approx(x: T) -> Result<Self, Error>
fn try_conv_approx(x: T) -> Result<Self, Error>
Try converting from T to Self, allowing approximation of value
This conversion may truncate excess precision not supported by the target type, so long as the value is approximately equal, from the point of view of precision of the target type.
This method should allow approximate conversion, but fail on input not (approximately) in the target’s range.
Provided Methods§
fn conv_approx(x: T) -> Self
fn conv_approx(x: T) -> Self
Converting from T to Self, allowing approximation of value
This method must return the same result as Self::try_conv_approx
where that method succeeds, but differs in the handling of errors:
- In debug builds the method panics on error
- Otherwise, the method may panic or may return a different value,
but like with the
askeyword all results must be well-defined and safe.
Default implementations use Self::try_conv_approx and panic on error.
Implementations provided by this library will panic in debug builds
or if the always_assert feature flag is used, and otherwise will
behave identically to the as keyword.
This mirrors the behaviour of Rust’s overflow checks on integer arithmetic in that it is a tool for diagnosing logic errors where success is expected.