Trait iter_python::extension_traits::Join [−][src]
pub trait Join: Display {
fn join<Iterable>(
&self,
iterable: Iterable
) -> DisplayableJoin<'_, Self, <Iterable as IntoIterator>::IntoIter>
where
Iterable: IntoIterator,
<Iterable as IntoIterator>::Item: Display,
{ ... }
}Expand description
separator.join(iterable) method on anything Displayable.
Note that the separator goes in first argument position (before the dot), following Python’s style.
The difference with stdlib’s .join() is that it can take a lazy
sequence of Displayables, such as Itertools::join(),
while also returning a lazy struct that, when Displayed, shall write
each item separated by self.
Example
ⓘ
use ::join_lazy_fmt::*;
let sequence = format!("[{}]", ", ".join(0 .. 5));
assert_eq!(sequence, "[0, 1, 2, 3, 4]");
// Since `.join()` is lazy, this does not compute an infinite string.
let _ = ", ".join(0 ..);
const N: usize = 6;
let line = format!("+-{}-+", "-+-".join((1 .. N).map(|_| "---")));
// And the following allocates only one `String`:
let matrix = format!(
"{line}\n{body}\n{line}\n",
line=line,
body="\n".join(
(1 .. N).map(|i| lazy_format!(
"| {row} |",
row=" | ".join(
(1 .. N).map(|j| lazy_format!(
"a{i}{j}",
i=i,
j=j,
))
),
))
),
);
assert_eq!(matrix, "\
+-----+-----+-----+-----+-----+
| a11 | a12 | a13 | a14 | a15 |
| a21 | a22 | a23 | a24 | a25 |
| a31 | a32 | a33 | a34 | a35 |
| a41 | a42 | a43 | a44 | a45 |
| a51 | a52 | a53 | a54 | a55 |
+-----+-----+-----+-----+-----+
");