block | 易学教程

WPF asynchronous Task<T> blocking UI

阅读更多关于 WPF asynchronous Task blocking UI

问题 I already worked with Task type. And all was good while Task return nothing. For example: XAML: <Button Name="_button" Click="ButtonBase_OnClick"> Click </Button> CodeBehind: private void ButtonBase_OnClick(object sender, RoutedEventArgs e) { _button.IsEnabled = false; Task.Factory.StartNew(() => { Thread.Sleep(5*1000); Dispatcher.Invoke(new Action(() => _button.IsEnabled = true)); }); } This works fine. But I want to Task returns some value, for example Boolean . So I need to use Task

Blocks & Procs in Ruby

阅读更多关于 Blocks & Procs in Ruby

问题 I have started learning Ruby, and I have read a couple of tutorials and I even bought a book ("Programming Ruby 1.9 - The Pragmatic Programmers' Guide"), and I came across something new that I haven't seen before in any of the other languages I know (I am working as a PHP webdeveloper). Blocks & Procs. I think I understand what they are, but what I don't understand is why they are so great, and when and why I should use them. Everywhere I look they say blocks and procs are a great feature in

Limitations of Java Anonymous Classes compared to Objective-C Blocks

阅读更多关于 Limitations of Java Anonymous Classes compared to Objective-C Blocks

问题 I'm just starting to wrap my head around first order functions and closures after discovering blocks in Objective-C. Java is another language where I've heard about closures (or lack thereof) and how anonymous classes make up for this somewhat. I can definitely see the advantages of closures as blocks in Objective-C, but what are the limitations of anonymous Java classes? To what extent do they 'somewhat' make up for the lack of true closures? 回答1: Java anonymous classes are really, really

What is the alternative to a non-static initialization block?

阅读更多关于 What is the alternative to a non-static initialization block?

问题 My projects had some developer who loved a non-static initialization block . What is the alternative to this and what is the downside of this alternative? I would guess: initialize the values in the constructor ? Why should we use a non-initialization block? As far as I understood the "initialization block" is used to set values when instantiating the class. Is a constructor then not sufficient? public class BlockTest { String test = new String(); //Non-static initialization block { test =

DSL block without argument in ruby

阅读更多关于 DSL block without argument in ruby

问题 I'm writing a simple dsl in ruby. Few weeks ago I stumbled upon some blog post, which show how to transform code like: some_method argument do |book| book.some_method_on_book book.some_other_method_on_book :with => argument end into cleaner code: some_method argument do some_method_on_book some_other_method_on_book :with => argument end I can't remember how to do this and I'm not sure about downsides but cleaner syntax is tempting. Does anyone have a clue about this transformation? 回答1: def

【翻译笔记】Hadoop分布式文件系统

阅读更多关于【翻译笔记】Hadoop分布式文件系统

摘要 Hadoop分布式文件系统（HDFS）设计用来可靠的存储超大数据集，同时以高速带宽将数据集传输给用户应用。在一个超大集群中，数以千计的服务器直接接触存储器和执行用户应用任务。通过许多服务器的分布式存储和计算，资源随需求增长的时候仍然可以保持经济性。我们解释了HDFS架构，同时介绍了我们在雅虎使用HDFS去管理25PB企业数据的经验。 1、介绍和相关工作 Hadoop 的一个重要特点是将数据和计算能力划分为小部分，通过许多（数千）主机运行，这些主机并行计算得到他们的结果。一个 Hadoop 集群通过简单增加商用服务器的数量来扩展其计算能力，存储能力和 IO 带宽。 1.1、与其他分布式系统的异同点相同点 HDFS 分别存储文件系统元数据和应用程序数据。与在其他分布式文件系统中相同，比如 PVFS 【 2 】【 14 】， Lustre 【 7 】和 GFS 【 5 】【 8 】， HDFS 在一个专门的服务器存储元数据，这个服务器被称为名称节点。应用程序数据存储在其他被称为数据结点的服务器上。不同点 HDFS中的数据节点并不使用数据保护机制比如RAID（独立磁盘冗余阵列），以确保数据持久性。相反。比如GFS，其文件内容在多个数据节点是重复的以确保可靠性。这个策略不仅仅可以确保数据持久性，还有额外的优点：数据变形带宽加倍

Find maximum pixel using BLOCKPROC in Matlab

阅读更多关于 Find maximum pixel using BLOCKPROC in Matlab

问题 In Matlab I've got a 3D matrix (over 100 frames 512x512). My goal is to find some representative points through the whole hyper-matrix. To do so I've implemented the traditional (and not very efficient) method: I subdivide the large matrix into smaller sub-matrices and then I look for the pixel with the highest value. After doing that I change those relative coordinates of that very pixel in the sub-matrix to global coordinates referenced to the large matrix. Now, I'm redesigning the

CSS中 inline、block、inline-block的区别

阅读更多关于 CSS中 inline、block、inline-block的区别

我们用firbug浏览别人网站时会发现设计者会在很多地方使用inline-block。我们都知道 inline是声明div是内联对象，block是声明块对象，那么inline-block是什么意思，即内联又成块？接下来做个测试，让我们了解一下三者的区别和作用吧： 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 <htmlxmlns=" http://www.w3.org/1999/xhtml "> <head> <metahttp-equiv="Content-Type"content="text/html; charset=utf-8"/> <title>inline、block、inline-block的区别</title> <style> .a{display:inline; width:100px; height:100px; padding:5px; background-color:#F00;} .b{display:block; width:100px; height:100px; padding:5px;background-color:#0f0;} .c{display:inline-block; width:100px;height:100px; padding:5px;background

How to call a method once the completion block finish?

阅读更多关于 How to call a method once the completion block finish?

问题 I want to call the signUp method first, once I got the userID, I need to call the another method normalSignupMethod . [ConnectionObj signUp:user]; [helper normalSignupMethod:dict]; signUp Method: [MYRequest signUp:user successBlock:^(QBResponse *response, QBUUser *user) { // Sign up was successful // Store user id [SingletonClass sharedMySingleton].userID = [NSString stringWithFormat:@"%@",response.data[@"id"]]; } errorBlock:^(QBResponse *response) { // Handle error here NSLog(@" error in

inline-block 前世今生

阅读更多关于 inline-block 前世今生

曾几何时，display:inline-block 已经深入「大街小巷」，随处可见「display:inline-block; *display:inline; *zoom:1; 」这样的代码。如今现代浏览器已经全面支持这个属性值了，上面的代码只是为了兼容 IE6、7 而已。那么你真的了解 inline-block 了吗？本文将带你深入剖析该属性值的前世今生，让你更好的理解和运用 inline-block。（本文约定 display:inline-block 简写为 inline-block）开篇我们来看几个问题： IE6、7 真的不支持 display:inline-block 吗？ display:inline-block 后的元素为什么会产生水平空隙，这真的是 bug 吗？如何更好的解决 display:inline-block 元素间产生的水平空隙？一、inline-block 前世 1.认知也许有人问你为何要写「 display:inline-block; *display:inline; *zoom:1; 」来兼容 IE6、7 时，你会立马答道：因为 IE6、7 不支持 display:inline-block 呗!不知道何时起，惯性思维给开发者带来了这样一个可怕的概念。万物都是辩证的，当你写下这些的时候，可曾怀疑过大众观点真的可靠吗？也许你认为这些无关