小编kni*_*ght的帖子

代码类似于以下内容,在函数中是Context结构的实现,定义如下:

struct Context {
    lines: isize,
    buffer: Vec<String>,
    history: Vec<Box<Instruction>>,
}

而功能,当然作为一种实现:

fn _execute_history(&mut self, instruction: &Instruction) -> Reaction {
    let num = instruction.suffix.parse::<usize>();
    match num {
        Ok(number) => {
            match self.history.get(number) {
                Some(ins) => { return self.execute(*ins); },
                _         => { /* Error handling */ }
            }
        }
        Err(..) => { /* Error handling */ }
    }
}

这不编译,我不明白错误信息.我在网上搜索类似的问题,我似乎无法在这里解决问题.我来自Python背景.完整的错误:

hello.rs:72:23: 72:35 note: previous borrow of `self.history[..]` occurs here; the immutable
borrow prevents subsequent moves or mutable borrows …

我正在研究一个主要返回闭包而不是传统的基于类的方法的Python项目.例如:

def term(token):
    def fn(text):
        return (...)
    return fn

可以想象,调试和测试闭包是一个噩梦,特别是如果我在整个代码中使用相同的名称来封闭.例如:

>>> term('t')
<function fn at 0x...>

所以我尝试将它包装在一个类中以__repr__从namedtuple中获取特殊处理:

def rr(cls, attrs):
    T = namedtuple(cls, attrs)

    class G(object):
        __slots__ = ()

        def __init__(self, repr_message, callable):
            self.callable = callable
            self.repr_message = repr_message

        def __call__(self, *args, **kwargs):
            return self.callable(*args, **kwargs)

        def __repr__(self):
            return self.repr_message

    K = type(cls, (G,), {})

    def wrapper(fn):
        def init(*args, **kwargs):
            t = T(*args, **kwargs)
            return K(
                repr(t),
                fn(*args, **kwargs),
            )
        return init
    return wrapper

这样:

>>> rr('Term', ['token'])(term)('$') …

所以我有这个代码,它返回有关该文件的一系列信息.它返回两次输出,如第二个片段所示.

list = os.listdir(".")
print Style.BRIGHT + "size        info        last-accessed    last-changed     filename" + Style.RESET_ALL
for f in list:
    info = os.stat(f)
    # "  size          info        last-accessed    last-changed     filename
    print " ", info[ST_SIZE], "                                                  " + f

并输出:

  size        info        last-accessed    last-changed     filename
  6243                                                   .bash_history
  55                                                   .bash_profile
  3                                                   .CFUserTextEncoding
  15364                                                   .DS_Store
  102                                                   .fontconfig
  105                                                   .sh_history
  102                                                   .ssh
  442                                                   .Trash
  0                                                   .Xauthority
  105                                                   console
  6688                                                   console.py
  272                                                   Desktop
  238                                                   Documents
  442                                                   Downloads
  2924                                                   Folder
  1156                                                   Library
  204                                                   Movies
  102                                                   Music
  136                                                   Pictures …