>
The former is easier to define, but has the downside of essentially “silencing warnings”. Let’s say the code was originally written to cast an u16 to u32, but later the variable type changes from u16 to u64 and the cast is now actually silently truncating things. Here we have casts becoming a sort of “silence all warnings”.Well … we even mention Rust in the paragraph right before this. In Rust, you can up a u16 to a u64 this way:
let bigger: u32 = x.into();
or
let bigger = u32::from(x);
The conversion `from` is infallible, because a u16 always fits in a u32. There is no `from(u64) -> u32`, because as the article notes, that would truncate, so if we did change the type to u64, the code would now fail to compile. (And we'd be forced to figure out what we want to do here.)
(There are fallible conversions, too, in the form of try_from, that can do u64 → u32, but will return an error if the conversion fails.)
Similarly, for,
for (uint x = 10; x >= 0; x--) // Infinte loop!
This is why I think implicit wrapping is a bad idea in language design. Even Rust went down the wrong path (in my mind) there, and I think has worked back towards something safer in recent years. But Rust provides a decent example here too; this is pseudo-code:
for (uint x = 10; x.is_some(); x = x.checked_sub(1))
Where `checked_sub` is returns `None` instead of wrapping, providing us a means to detect the stopping point. So, something like that. (Though you'd probably also want to destructure the option into the uint for use inside the loop.) Of course, higher-level stuff always wins out here, I think, and in Rust you wouldn't write the above; instead something like,
for x in (0..=10).rev()
(And even then, if we
need indexes; usually, one would prefer to iterate through a slice or something like that. The higher-level concept of iterators usually dispenses with most or all uses of indexes, and in the rare cases when needed, most languages provide something like `enumerate` to get them from the iterator.)