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0.3.1 | Oct 6, 2023 |
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0.2.5 | Dec 31, 2018 |
0.2.4 | Jul 21, 2018 |
0.2.3 | Aug 5, 2017 |
0.1.2 | Jan 21, 2017 |
#729 in Rust patterns
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Used in 5 crates
(via kompact)
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This module implements a very opinionated approach to converting numbers.
Imagine you have a function return_u32
, and you would like to pass its return value into some
other function take_i8:
fn return_u32() -> u32 {
257
}
fn take_i8(i: i8) {
}
Then, the compiler (correctly) complains as soon as you write take_i8(return_u32())
.
I came into those situations frequently, so I simply changed it to
take_i8(return_u32() as i8)
. However, when doing so, I implicitly assumed that the semantic
meaning of the number does not change, i.e. I assume that i8
is capable of representing the
exact same value that return_u32
gives me (which is not the case in the example shown).
This module enables you to write the following:
use as_num::TAsNum; // TAsNum is the trait enabling the conversions
take_i8(return_u32().as_num())
as_num
converts its argument into the destination type, thereby checking whether the
conversion can be done without loss of data.
It tries to follow a similar approach to the one that is chosen with e.g. "normal addition" and checked_add
:
It offers one method as_num
that does the conversion (at last going down to Rust's as
), and
debug_assert
s that the conversion is lossless.
In addition to as_num
, it offers a method checked_as_num
, returning an Option
.
This module implements conversion for any combination of the following types:
i8
, i16
, i32
, i64
, isize
, u8
, u16
, u32
, u64
, usize
, f32
, f64
.
The function as_num
debug_assert
s that the destination value is convertible back to the
exact same source value.
That, in particular, means that converting floating-point to integral numbers can only be done
with as_num
if the source is already been rounded to some integral number.