Question

class Array:
    def __init__(self):
        self.list = []

    def add(self, num):
        self.list.append(num)

a = Array()
a.add(1).add(2)

我想将数字1,2添加到self.list中。我该如何实施？

Answer 1

返回对象本身

using System;
using System.Net;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;

namespace WebClientAsync
{

    public partial class MainWindow : Window
    {

        const string SRC = "http://ovh.net/files/10Mio.dat";
        const string TARGET = @"d:\stuff\10Mio.dat";
        // Time needed to restore network connection
        const int TIMEOUT = 30 * 1000;

        public MainWindow()
        {
            InitializeComponent();
        }

        private async void btnDownload_Click(object sender, RoutedEventArgs e)
        {
            btnDownload.IsEnabled = false;
            btnDownload.Content = "Downloading " + SRC;
            CancellationTokenSource cts = new CancellationTokenSource();
            CancellationToken token = cts.Token;
            Timer timer = new Timer((o) =>
                {
                    // Force async cancellation
                    cts.Cancel();
                }
                , null //state
                , TIMEOUT
                , Timeout.Infinite // once
            );
            DownloadProgressChangedEventHandler handler = (sa, ea) =>
                {
                    // Restart timer
                    if (ea.BytesReceived < ea.TotalBytesToReceive && timer != null)
                    {
                        timer.Change(TIMEOUT, Timeout.Infinite);
                    }

                };
            btnDownload.Content = await DownloadFileTA(token, handler);
            // Note ProgressCallback will fire once again after awaited.
            timer.Dispose();
            btnDownload.IsEnabled = true;
        }

        private async Task<string> DownloadFileTA(CancellationToken token, DownloadProgressChangedEventHandler handler)
        {
            string res = null;
            WebClient wcl = new WebClient();
            wcl.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials;
            wcl.DownloadProgressChanged += handler;
            try
            {
                using (token.Register(() => wcl.CancelAsync()))
                {
                    await wcl.DownloadFileTaskAsync(new Uri(SRC), TARGET);
                }
                res = "Downloaded";
            }
            catch (Exception ex)
            {
                res = ex.Message + Environment.NewLine
                    + ((ex.InnerException != null) ? ex.InnerException.Message : String.Empty);
            }
            wcl.Dispose();
            return res;
        }
    }
}

Answer 2

插入后返回实例本身进行第二次操作，然后您将拥有实例本身，以便执行添加操作：

Replace All

Answer 3

作为替代方法，为什么不让您的add方法将值列表作为输入？看起来像这样更容易使用

def add(self, vals):
    self.list += vals

所以现在你可以

a.add([1,2])

而不是

a.add(1).add(2)

如何在Python中实现链操作？

3 个答案: