writeonly

Perl进程间通信

由 三世轮回 提交于 2020-04-13 16:17:56
【今日推荐】：为什么一到面试就懵逼！>>> 不同进程之间的通信或进程间通信(InterProcess Communication, IPC)，是一个涉及多个方面的主题。Perl提供了多种进程间通信的方式，本文将逐一介绍。本文的内容主体来自于《Pro Perl》的第21章。 单向管道(unidirectional pipe) 管道是两个文件描述符(文件句柄)通过一根管道连接起来，一端的文件句柄读，另一端的文件句柄写，从而实现进程间的通信。 Perl使用 pipe 函数可以创建单向管道，也就是一端只可读、一端只可写的管道，所以它需要两个文件句柄参数。 pipe READ_FH, WRITE_FH; 默认情况下，Perl会对IO进行缓冲，向写入端文件句柄写入数据时会暂时缓冲在文件句柄的缓冲中，而不会立即放进管道，也就是说读入端无法立即读取到这段数据。对于管道这种数据实时通信的机制， 应该关闭缓冲，而是让它在需要写入数据的时候立即刷到管道中 。 pipe READ_FH, WRITE_FH; # when write to WRITE_FH select WRITE_FH; $| = 1; # 或者使用IO::Handle设置autoflush(1) WRITE_FH->autoflush(1); 下面是一个父子进程间通过单向pipe通信的示例：父进程写、子进程读 #!/usr/bin

基于Asp.Net Core，利用ZXing来生成二维码的一般流程

由 馋奶兔 提交于 2020-04-09 16:37:33
　　本文主要介绍如何在.net环境下，基于Asp.Net Core，利用ZXing来生成二维码的一般操作。对二维码工作原理了解，详情见： https://blog.csdn.net/weixin_36191602/article/details/82466148 文章介绍。 1、前期准备 　　.net core preview8，vs2019（用于支持core3.0），二维码生成插件：开源库ZXIng。相关插件可以在github上找到。安装vs2019后新建.net core web解决方案，也可以右键该解决方案，通过管理解决方案Nuget包功能来找到。如下图：浏览中搜索Zxing第一个既是。选中安装即可。 　　可通过项目中依赖性查看相应包的引用。如图： 2.二维码生成 2.1前端页面 在login.cshtml页面中添加前端元素，主要是一个图片控件。 1 < div style ="text-align:center" > 2 < div style ="margin-top:20px" > 3 < span > 扫码获取 </ span >< br /> 4 < img id ="barcode" width ="400" height ="400" alt ="扫码获取" src ="Dynpass/GetBarCode" /> 5 </ div > 6 </ div >

How can I create a custom *write-only* dependency-property?

由 ﹥＞﹥吖頭↗ 提交于 2019-12-21 05:21:34
问题 I need to know what the procedure is for making a write-only dependency-property. I can see that the DependencyProperty class does not have a special "Register" method for write-only properties, but I have no idea whether the RegisterAttached method may apply to what I am trying to do. This property needs to be a dependency-property, rather than a simple CLR property. Internally, my class requires a PropertyChangedCallback on this property in order to remain stable. I know that write-only

Java thread-safe write-only hashmap

由 一曲冷凌霜 提交于 2019-12-10 10:14:27
问题 In my Java class I include a Hashmap variable (class property) and run some Threads which write-only into that HashMap using put() : each time the write happens it stores a unique key (which is done by design). Is the synchronized keyword on a class method write-only sufficient for thead-safe conditions? My HashMap is simple and not a ConcurrentHashMap ? 回答1: No, it is not sufficient to only synchronize the writes. Synchronization must be applied to both reads and writes to memory. Some other

DRF 用户密码验证

由 一世执手 提交于 2019-12-05 04:39:22
密码字段验证 参考 serializers.py from django.contrib.auth import password_validation class PhoneCodeSerializer(BaseSerializer): code = serializers.CharField( required=True, allow_blank=False, min_length=4, max_length=4, help_text='验证码', error_messages={ 'blank': '请输入验证码', 'required': '请输入验证码', 'min_length': '验证码格式错误', 'max_length': '验证码格式错误', }) phone = PhoneField( required=True, max_length=11, min_length=11, help_text='手机号') def validate_code(self, code): """ code.create user.receive user.register t1 t2 t3 5min内: t3-t1<5 t3-5<t1: 5min内 t3-5>t1: 过期 :param code: :return: """ last_record = VerifyCode

How can I create a custom *write-only* dependency-property?

由 天涯浪子 提交于 2019-12-03 20:09:23
I need to know what the procedure is for making a write-only dependency-property. I can see that the DependencyProperty class does not have a special "Register" method for write-only properties, but I have no idea whether the RegisterAttached method may apply to what I am trying to do. This property needs to be a dependency-property, rather than a simple CLR property. Internally, my class requires a PropertyChangedCallback on this property in order to remain stable. I know that write-only dependency-properties can be created, because it is stated quite clearly in: Pro C# 2008 and the .NET 3.5

C# compiler bug? Object initializer syntax used for write-only property in Expression makes csc crash

由 ♀尐吖头ヾ 提交于 2019-12-03 05:39:50
问题 You may consider this a bug report, however I'm curious if I am terribly wrong here, or if there is an explanation from Eric or someone else at Microsoft. Update This is now posted as a bug on Microsoft Connect. Description Consider the following class: class A { public object B { set { } } } Here, A.B is a write-only but otherwise fine property. Now, imagine we assign it inside of expression : Expression<Func<A>> expr = () => new A { B = new object { } }; This code makes C# compiler (both 3

C# compiler bug? Object initializer syntax used for write-only property in Expression makes csc crash

由 只愿长相守 提交于 2019-12-02 18:59:24
You may consider this a bug report, however I'm curious if I am terribly wrong here, or if there is an explanation from Eric or someone else at Microsoft. Update This is now posted as a bug on Microsoft Connect. Description Consider the following class: class A { public object B { set { } } } Here, A.B is a write-only but otherwise fine property. Now, imagine we assign it inside of expression : Expression<Func<A>> expr = () => new A { B = new object { } }; This code makes C# compiler (both 3.5 .30729.4926 and 4.0 .30319.1) spit out Internal Compiler Error (0xc0000005 at address 013E213F):
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