pipeline

I understand that PowerShell piping works by taking the output of one cmdlet and passing it to another cmdlet as input. But how does it go about doing this? Does the first cmdlet finish and then pass all the output variables across at once, which are then processed by the next cmdlet? Or is each output from the first cmdlet taken one at a time and then run it through all of the remaining piped cmdlet’s? You can see how pipeline order works with a simple bit of script: function a {begin {Write-Host 'begin a'} process {Write-Host "process a: $_"; $_} end {Write-Host 'end a'}} function b {begin

I can't think of any way to implement pipelining in c that would actually work. That's why I've decided to write in here. I have to say, that I understand how do pipe/fork/mkfifo work. I've seen plenty examples of implementing 2-3 pipelines. It's easy. My problem starts, when I've got to implement shell, and pipelines count is unknown. What I've got now: eg. ls -al | tr a-z A-Z | tr A-Z a-z | tr a-z A-Z I transform such line into something like that: array[0] = {"ls", "-al", NULL"} array[1] = {"tr", "a-z", "A-Z", NULL"} array[2] = {"tr", "A-Z", "a-z", NULL"} array[3] = {"tr", "a-z", "A-Z",

I am having some trouble with a scrapy pipeline. My information is being scraped form sites ok and the process_item method is being called correctly. However the spider_opened and spider_closed methods are not being called. class MyPipeline(object): def __init__(self): log.msg("Initializing Pipeline") self.conn = None self.cur = None def spider_opened(self, spider): log.msg("Pipeline.spider_opened called", level=log.DEBUG) def spider_closed(self, spider): log.msg("Pipeline.spider_closed called", level=log.DEBUG) def process_item(self, item, spider): log.msg("Processsing item " + item['title'],

Is there a way to write pipelined functions in R where the result of one function passes immediately into the next? I'm coming from F# and really appreciated this ability but have not found how to do it in R. It should be simple but I can't find how. In F# it would look something like this: let complexFunction x = x |> square |> add 5 |> toString In this case the input would be squared, then have 5 added to it and then converted to a string. I'm wanting to be able to do something similar in R but don't know how. I've searched for how to do something like this but have not come across anything.

Modern CPUs have extensive pipelining, that is, they are loading necessary instructions and data long before they actually execute the instruction. Sometimes, the data loaded into the pipeline gets invalidated, and the pipeline must be cleared and reloaded with new data. The time it takes to refill the pipeline can be considerable, and cause a performance slowdown. If I call a function pointer in C, is the pipeline smart enough to realize that the pointer in the pipeline is a function pointer, and that it should follow that pointer for the next instructions? Or will having a function pointer

How do I access the scrapy settings in settings.py from the item pipeline. The documentation mentions it can be accessed through the crawler in extensions, but I don't see how to access the crawler in the pipelines. The way to access your Scrapy settings (as defined in settings.py ) from within your_spider.py is simple. All other answers are way too complicated. The reason for this is the very poor maintenance of the Scrapy documentation, combined with many recent updates & changes. Neither in the "Settings" documentation " How to access settings ", nor in the "Settings API" have they bothered

It is said that pipeline is a better way when many set/get is required in redis, so this is my test code: public class TestPipeline { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub JedisShardInfo si = new JedisShardInfo("127.0.0.1", 6379); List<JedisShardInfo> list = new ArrayList<JedisShardInfo>(); list.add(si); ShardedJedis jedis = new ShardedJedis(list); long startTime = System.currentTimeMillis(); ShardedJedisPipeline pipeline = jedis.pipelined(); for (int i = 0; i < 100000; i++) { Map<String, String> map = new HashMap<String, String>();

I have written a simple PowerShell filter that pushes the current object down the pipeline if its date is between the specified begin and end date. The objects coming down the pipeline are always in ascending date order so as soon as the date exceeds the specified end date I know my work is done and I would like to let tell the pipeline that the upstream commands can abandon their work so that the pipeline can finish its work. I am reading some very large log files and I will frequently want to examine just a portion of the log. I am pretty sure this is not possible but I wanted to ask to be

boolean a = false, b = true; if ( a && b ) { ... }; In most languages, b will not get evaluated because a is false so a && b cannot be true. My question is, wouldn't short circuiting be slower in terms of architecture? In a pipeline, do you just stall while waiting to get the result of a to determine if b should be evaluated or not? Would it be better to do nested ifs instead? Does that even help? Also, does anyone know what short-circuit evaluation is typically called? This question arose after I found out that my programming friend had never heard of short-circuit evaluation and stated that