block

Block definition - difference between braces and do-end?

由 允我心安 提交于 2019-12-17 04:07:53
问题 can anybody explain why the following code aborts with an error irb(main):186:0> print ((1..10).collect do |x| x**2 end) SyntaxError: (irb):186: syntax error, unexpected keyword_do_block, expecting ')' print ((1..10).collect do |x| x**2 end) ^ (irb):186: syntax error, unexpected keyword_end, expecting $end print ((1..10).collect do |x| x**2 end) ^ from /usr/bin/irb:12:in `<main>' whereas following code with the same functionality works as expected ? irb(main):187:0> print ((1..10).collect {

Returning method object from inside block

由 寵の児 提交于 2019-12-16 20:05:35
问题 I am wondering how to do the following correctly: I have a method that is to return an NSData object. It gets the NSData object from a UIDocument . The NSData object can get large, so I want to make sure it is fully loaded before the response starts. I would therefore like to return the value of the method from within the block itself. So something like this: - (NSData*)getMyData { MyUIDocument *doc = [[MyUIDocument alloc] initWithFileURL:fileURL]; [doc openWithCompletionHandler:^(BOOL

HOG：从理论到OpenCV实践

由 孤人 提交于 2019-12-16 02:57:01
OpenCV HOGDescriptor 参数图解 原文链接 一、理论 1、 HOG特征描述子的定义 ： locally normalised histogram of gradient orientation in dense overlapping grids，即局部归一化的梯度方向直方图， 是一种对图像局部重叠区域的密集型描述符, 它通过计算局部区域的梯度方向直方图来构成特征。 2、本质： Histogram of Oriented Gradient descriptors provide a dense overlapping description of image regions ，即 统计图像局部区域的梯度方向信息来作为该局部图像区域的表征。 3、OpenCV中的HOG算法来源： Histograms of Oriented Gradients for Human Detection , CVPR 2005。详细的算法可以参考这个文章。这里是 英文 和 中文 的介绍。 4、 检测窗口Win、块Block、单元格Cell的基本信息 (1)大小： A、检测窗口：WinSize=128*64像素，在图像中滑动的步长是8像素(水平和垂直都是) B、块：BlockSize=16*16像素，在检测窗口中滑动的步长是8像素(水平和垂直都是) C、单元格：CellSize=8*8像素

Linux文件系统管理

由 爱⌒轻易说出口 提交于 2019-12-15 16:51:15
（整理自《鸟哥的Linux私房菜》书籍） 1. 文件系统特性 我们都知道磁盘分区完毕后还需要进行格式化(format)，之后操作系统才能够使用这个文件系统。 为什么需要进行『格式化』呢？这是因为每种操作系统所设定的文件属性/权限并不相同， 为了存放这些文件所需的数据，因此就需要将分区槽进行格式化，以成为操作系统能够利用的文件系统格式(filesystem)。 一个可被挂载的数据为一个文件系统而不是一个分区槽。 文件系统是如何运作的？ 这与操作系统的文件数据有关。较新的操作系统的文件数据除了文件实际内容外， 通常含有非常多的属性，例如 Linux 操作系统的文件权限(rwx)与文件属性(拥有者、群组、时间参数等)。 文件系统通常会将这两部份的数据分别存放在不同的区块，权限与属性放置到 inode 中，至于实际数据则放置到 data block 区块中。还有一个超级区块 (superblock) 会记录整个文件系统的整体信息，包括 inode 与 block 的总量、使用量、剩余量等。 每个 inode 与 block 都有编号，至于这三个数据的意义可以简略说明如下： • superblock：记录此 filesystem 的整体信息，包括 inode/block 的总量、使用量、剩余量， 以及文件系统的格式与相关信息等； • inode：记录文件的属性，一个文件占用一个 inode

How to create generic closures in Swift

由 孤人 提交于 2019-12-13 15:07:04
问题 I would like to create a function that uses generic closure (block) in swift. My first attempt was to do like : func saveWithCompletionObject(obj : AnyObject, success : AnyObject -> Void, failure : Void -> Void) But as soon as I call this function with another block, such as : func doSomething(success : String -> Void, failure : Void -> Void) { saveWithCompletionObject("Example", success, failure) } I get an error : 'AnyObject' is not a subtype of 'String' Thanks in advance ! 回答1: You cannot

What is begin…end in Erlang used for?

由 浪子不回头ぞ 提交于 2019-12-13 11:59:04
问题 I just stomped at a begin...end in Erlang's documentation (here), but it doesn't give some examples of how it is useful. Looking here in StackOverflow I found two cases where people would be using begin...end , both in list comprehensions: https://stackoverflow.com/a/5645116/979505 https://stackoverflow.com/a/5141263/979505 But I wonder if there are more of such uses. Can anyone provide another scenario in which a begin...end is useful in Erlang? Thanks 回答1: Macros, for example: -define(M(A,

Crash at _CFAutoreleasePoolPop

由 江枫思渺然 提交于 2019-12-13 07:32:17
问题 I got a crash from Fabric ,the stack is below: Thread : Crashed: com.apple.main-thread 0 libobjc.A.dylib 6806634868 objc_release + 20 1 libsystem_blocks.dylib 6813456656 _Block_release + 256 2 libobjc.A.dylib 6806640420 (anonymous namespace)::AutoreleasePoolPage::pop(void*) + 564 3 CoreFoundation 6529519172 _CFAutoreleasePoolPop + 28 4 UIKit 6605817924 _wrapRunLoopWithAutoreleasePoolHandler + 76 5 CoreFoundation 6530394704 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 32 6

Returning method object from inside block

由 戏子无情 提交于 2019-12-13 07:23:48
问题 I am wondering how to do the following correctly: I have a method that is to return an NSData object. It gets the NSData object from a UIDocument . The NSData object can get large, so I want to make sure it is fully loaded before the response starts. I would therefore like to return the value of the method from within the block itself. So something like this: - (NSData*)getMyData { MyUIDocument *doc = [[MyUIDocument alloc] initWithFileURL:fileURL]; [doc openWithCompletionHandler:^(BOOL

Ruby Hash declaration with an inline block in the middle

由 家住魔仙堡 提交于 2019-12-13 04:58:55
问题 Here is an XML document: <Request> <Field1>value1</Field1> <Field2>value2</Field2> <Section1> <Field attribute1="attrval1">value11</Field> <Field attribute1="attrval2">value12</Field> <Field attribute1="attrval3">value13</Field> <Field attribute1="attrval4">value14</Field> </Section1> <Section2> <Fld1>value21</Fld1> <Fld2>value22</Fld2> <Fld3>value23</Fld3> </Section2> </Request> which is parsed by following Ruby code: xml = Nokogiri::XML(request.raw_post) req = xml.xpath('/Request') hash = {

Extract TU Partitioning Information in HEVC Reference Software 16.18

由 北城余情 提交于 2019-12-13 03:57:01
问题 I want to extract CU/PU/TU partitioning data from HEVC HM encoder. I could extract CU/PU partitioning information using getHeight/getWidth/getPartitionSize functions in TComDataCU class. But, don't know how to access TU partitioning information. Please help. 回答1: You can do it easily on the decoder side. You need to find the function parseCoeffNxN and then access the TU size with uiWidth and uiHeight . Start with this simple test and then give feedbacks here. If there's a problem, we will
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