Macro slice_sep

macro_rules! slice_sep {
    ($inner:expr) => { ... };
    ($inner:expr, $sep:expr) => { ... };
}

👎Deprecated since 0.8.0-rc.1: Use string_v2 instead, v1 will be removed in 0.9.0.

Create a SliceSep.

Examples

Generally, this macro takes a slice of StringExtT types, like Vec<T> or &[T] where T implements StringExtT.

let slice_sep = slice_sep!(["a", "b", "c"], ',');
assert_eq!(
    str_concat!("Hello: ", &slice_sep, " World!"),
    "Hello: a,b,c World!"
);
let slice_sep = slice_sep!(vec!["a", "b", "c"], ',');
assert_eq!(
    str_concat!(sep = ';'; "TEXT_1", slice_sep, "2_TEXT"),
    "TEXT_1;a,b,c;2_TEXT"
);

Map is accepted too.

let slice_sep = slice_sep!(["a", "b", "c"].iter().map(|s| s.to_ascii_uppercase()), ',');
assert_eq!(
    str_concat!("Hello: ", slice_sep, " World!"),
    "Hello: A,B,C World!"
);

In fact all types that implements StringExtT can be used, though useless and do not do so.

let slice_sep = slice_sep!("a", ',');
assert_eq!(
    str_concat!(sep = ';'; "TEXT_1", &slice_sep, "2_TEXT"),
    "TEXT_1;a;2_TEXT"
);

Notes

Take the following as an example:

let post_ids = vec![1, 2, 3];
let l = slice_sep!(
    post_ids
        .iter()
        .map(|id| { slice_sep!(("post_ids[]=", id), "") }),
    '&'
)
.to_string_ext();
let r = slice_sep!(post_ids.iter().map(|id| { ("post_ids[]=", id) }), '&').to_string_ext();
assert_eq!(l, r);

Since the contents in tuple like ("post_ids[]=", id) are recognized as independent, the separator will be also inserted between them.

To avoid this, you can use slice_sep! with an empty separator to avoid recognizing the contents as independent, while () is better:

let post_ids = vec![1, 2, 3];
let l = slice_sep!(
    post_ids
        .iter()
        .map(|id| { slice_sep!(("post_ids[]=", id), "") }),
    '&'
)
.to_string_ext();
let r = slice_sep!(
    post_ids
        .iter()
        .map(|id| { slice_sep!(("post_ids[]=", id)) }), // No separator specified.
    '&'
)
.to_string_ext();
assert_eq!(l, r);