block

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? Java anonymous classes are really, really wordy. Apart from the vast amounts of boilerplate that you need just to define them, some of Java's design

Whats the difference between DataAnnotations and Application Validation Block? DataAnnotations is an attribute based model to 'annotate' your data and it is in the .NET framework itself. Its most obvious use is for validation, as ASP.NET MVC does for instance. Validation Application Block itself is a validation framework, created by the Microsoft P&P team, but it is not part of the .NET framework. It also contains attributes to 'annotate' your data and in its newest version (5.0) the attributes inherit from DataAnnotations, making it interchangeable with DataAnnotations to some extent.

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? def some_method argument, &blk #... book.instance_eval &blk #... end UPDATE: However, that omits book but don't

导语 不会使用block的iOS程序员，不是一个合格的程序员 学会了block，你再也不想用繁琐的代理 block没有你想象中的那么难，不要害怕，不要畏惧，勇敢尝试 笔者入行iOS时已经是ARC的天下，所以这里只说ARC环境下的使用 什么是block block其实就是一个代码块，把你想要执行的代码封装在这个代码块里，等到需要的时候再去调用。那block是OC对象吗？答案是肯定的 来自官方文档 笔者以英语3.9级的水平给大家翻译下，“block是一个OC对象，这意味着它能被添加到集合，比如NSArray、NSDictionary” block的定义 block属性或变量 格式：返回值类型(^block名称)(参数列表) / 定义属性，block属性可以用strong修饰，也可以用copy修饰 有小伙伴留言说苹果官方建议用copy，笔者查了下文档, 确实是这样的，不过笔者未测试出copy与strong的区别，大家喜欢啥就用啥吧 / @property (nonatomic, strong) void(^myBlock)();//无参无返回值 @property (nonatomic, strong) void(^myBlock1)(NSString *);//带参数 @property (nonatomic, strong) NSString *(^myBlock2)

之前写过一篇 博客 ，把Block跟delegate类比，说明了使用block，可以通过更少的代码实现代理的功能。那篇博客将block定义为类的property。 过了这么长时间，对于block的内容有了很多的遗忘，果然block的语法比较操蛋，容易遗忘，还是看看 http://fuckingblocksyntax.com/ ，复习一下操蛋的block语法，我翻译如下， （1）block作为本地变量（local variable） returnType (^blockName)(parameterTypes) = ^returnType(parameters){... }; （2）block作为类的成员属性（@property） @property (nonatomic, copy) returnType (^blockName)(parameters); 这时候可以类比delegate，实现代理功能。 （3）block作为函数参数（method parameter） - (void)someMethodThatTakesABlock:(returnType (^)(parameterTypes))blockName; 调用包括block参数的函数， [someObject somethodThatTakesABlock:^returnType(parameters){...}];

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 = "testString"; } } This block confuses me and lead to reduced readability. Thanks for your response! First

index.py from flask import Flask,render_template from flask_bootstrap import Bootstrap #初始化 app = Flask(__name__) bootstrap = Bootstrap(app) #路由，处理URL 和函数之间关系的程序称为路由 @app.route('/') #视图函数，函数执行，返回结果 def index(): return render_template('index.html') @app.errorhandler(404) def page_not_found(e): return render_template('404.html'), 404 @app.errorhandler(500) def internal_server_error(e): return render_template('500.html'), 500 #启动服务器 if __name__ == '__main__': app.run() base.html {% extends "bootstrap/base.html" %} {% block title %}Flasky{% endblock %} {#包含导航条的程序基模板#} {% block navbar %} <div class

我們常聽到的LVM與軟體磁碟陣列(software raid)， 這些技術可以將一個分割槽格式化為多個檔案系統(例如LVM)，也能夠將多個分割槽合成一個檔案系統(LVM, RAID)！ 所以說，目前我們在格式化時已經不再說成針對 partition 來格式化了， 通常我們可以稱呼 一個可被掛載的資料為一個檔案系統而不是一個分割槽喔！ superblock：記錄此 filesystem 的整體資訊，包括inode/block的總量、使用量、剩餘量， 以及檔案系統的格式與相關資訊等； inode：記錄檔案的屬性，一個檔案佔用一個inode，同時記錄此檔案的資料所在的 block 號碼； block：實際記錄檔案的內容，若檔案太大時，會佔用多個 block 。 data block： data block 是用來放置檔案內容資料地方， 在 Ext2 檔案系統中所支援的 block 大小有 1K, 2K 及 4K 三種而已。在格式化時 block 的大小就固定了，且每個 block 都有編號，以方便 inode 的記錄啦。 原則上，block 的大小與數量在格式化完就不能夠再改變了(除非重新格式化)； 每個 block 內最多只能夠放置一個檔案的資料； 承上，如果檔案大於 block 的大小，則一個檔案會佔用多個 block 數量； 承上，若檔案小於 block ，則該 block

hdfs fsck / Connecting to namenode via http://localhost:9870/fsck?ugi=liugen&path=%2F FSCK started by liugen (auth:SIMPLE) from /127.0.0.1 for path / at Wed Oct 24 20:39:11 PDT 2018 Status: HEALTHY //集群状态健康 Number of data-nodes: 1 //集群有多少数据节点 Number of racks: 1 //集群有多少机架 Total dirs: 7 //集群有多少个目录 Total symlinks: 0 //集群有多少链接 Replicated Blocks: Total size: 54396813 B //集群总共文件大小 Total files: 3 //集群有多少个文件 Total blocks (validated): 2 (avg. block size 27198406 B) //多少个数据块 通过验证的有2块 平均块大小是27xxx Minimally replicated blocks: 2 (100.0 %) //最少复制的块数 Over-replicated blocks: 0 (0.0 %) //超过预计复制数目的块有几个（比如说