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我試圖通過Rust by Example website上的「Tuple課程」,但我被卡在格式化的輸出實現上。我有這樣的代碼,它打印傳遞矩陣:獲取字符串作爲格式化輸出中的值
#[derive(Debug)]
struct Matrix{
data: Vec<Vec<f64>> // [[...], [...],]
}
impl fmt::Display for Matrix {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let output_data = self.data
// [[1, 2], [2, 3]] -> ["1, 2", "2, 3"]
.into_iter()
.map(|row| {
row.into_iter()
.map(|value| value.to_string())
.collect::<Vec<String>>()
.join(", ")
})
.collect::<Vec<String>>()
// ["1, 2", "2, 3"] -> ["(1, 2)", "(2, 3)"]
.into_iter()
.map(|string_row| { format!("({})", string_row) })
// ["(1, 2)", "(2, 3)"] -> "(1, 2),\n(2, 3)"
.collect::<Vec<String>>()
.join(",\n");
write!(f, "{}", output_data)
}
}
但是,編譯器打印一條消息:
<anon>:21:40: 21:44 error: cannot move out of borrowed content [E0507]
<anon>:21 let output_data = self.data
^~~~
<anon>:21:40: 21:44 help: see the detailed explanation for E0507
error: aborting due to previous error
playpen: application terminated with error code 101
我試着換output_data
的成績爲RefCell
,但編譯仍然打印此錯誤。我如何解決這個問題,以便write!
宏能夠正常工作?