for x in y { if x.something() { z }} should be for x in y.filter(|x| !x.something()) { z }

[oli-obk]

encountered in the wild: https://github.com/Manishearth/rust-clippy/issues/600#issuecomment-184735383

for x in y {
    if x.something() {
        operate_on(x);
    }
}

and

for x in y {
    if !x.something() { continue }
    operate_on(x);
}

should be

for x in y.filter(|x| x.something()) {
    operate_on(x);
}

[fhartwig]

This is too subjective to make it Warn by default, in my opinion,.

[oli-obk]

This is too subjective to make it Warn by default, in my opinion,.

allow is fine by me

[llogiq]

Yeah, it's less readable IMHO.

[mcarton]

I’m not sure I would want that by default either.

[killercup]

If we suggest

for x in y.iter().filter(…) {
    stuff(x);
}

we might as well suggest itertool's foreach because it reads nicer:

y.iter().filter(…).foreach(stuff);

(Another option would of course be to write

let y = y.iter().filter(…);
for x in &y {
   stuff(x);
}

but that just seems to split the logic.)

[llogiq]

A recent thread on internals suggests that different versions of zips that should do the same thing exhibit differing performance characteristics, so we should tread lightly here until they have this figured out.

I personally like for loops for doing stuff when no result is collected and using iterator methods when manipulating sequences or collections of data.

[oli-obk]

I agree that this is not a good idea.