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• How to make html-files with content to be used in a simple ajax site to behave nicely in google?

  - by metatron

  I made some ajax sites in the past where I used ajax to get more of a desktop application feeling for my sites and also to keep the site maintainable. My strategy was making one index page and from there pulling in html content from some subpages. (So far I didn't use ajax to send data to the server.) The problem that I ran into is this: I want the subpages to be readable by google since they contain valuable content but once they show up in google's results they lead to the naked html-file (no css nor Javascript). I solved this by putting a javascript redirect (window.location = ...) on the subpages so they lead to the correct page. So as an example let's say I have a site at example.com with some javascript and css and a naked content page that should be loaded via ajax: example.com/content.html. Via ajax I pull in what I need from the content file but since my index.html contains href's to the content.html file (I want the content of my ajax site to be readable without Javascript) it will be indexed by google and gets listed in the search results. But I don't want people to see the naked html file. Hence the redirect that goes to the index page and gets handled by some Javascript to show the content as I want it to be showed. I was wondering if there are nicer solutions to this problem or different approaches.

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• Background loading javascript into iframe without using jQuery/Ajax?

  - by user210099

  I'm working on an offline only help system which requires loading a large amount of search-related data into an iframe before the search functionality can be used. Due to the folder structure of the project, I am unable to use Ajax-related background load methods, since the files I need are loaded a few directories "up and over." I have written some code which delays the loading of the help data until the rest of the webpage is loaded. The help data consists of a bunch of javascript files which have information about the terms, ect that exist in the help books which are installed on the system. The webpage works fine, until I start to load this help data into a hidden iframe. While the javascript files are loading, I can not use any of the webpage. Links that require a small files be downloaded for hover over effects don't show up, javascript (switching tabs on the page) has no effect. I'm wondering if this is just a limitation of the way javascript works, or if there's something else going on here. Once all the files are loaded for the help system, the webpage works as expected. function test(){ var MGCFrame = eval("parent.parent"); if((ALLFRAMESLOADED == true)){ t2 = MGCFrame.setTimeout("this.IHHeader.frames[0].loadData()",1); } else{ t1 = MGCFrame.setTimeout("this.IHHeader.frames[0].test()",1000); } } Load data simply starts the data loading process. Thanks for any help you can provide.

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• Integrating jQuery autocomplete with Google site search

  - by user1715700

  I have a bit of an odd situation. I have to implement search on a public facing website -but, that search must be able to search both web pages and have an autocomplete/suggestion functionality that comes from a list of terms that are in a DB table. So, I'm wondering a couple things: 1) should I be looking at Google search and jQuery autocomplete? 2) is there something else I should be looking at instead? 3) if this is the right path to be heading down are the enough pointers on implementation? The crux of my problem is that the terms that I need to use for the autocomplete/suggest functionality reside within a database and not on the webpages. So, I thought Google would be appropriate for search the webpages and that I could sort of fill in the blanks so to speak with these terms from the DB. I'm going to say that there are roughly 20-40,000 terms or so that need autocomplete. But that is really just a very rough guess -it could be less. I'm open to ideas and not really married to any particular solution. However, I will admit to liking the ideas of offloading the search to Google. I hear they have a good algorithm ;) Any ideas, thoughts, or leads are greatly appreciated!

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• C# InternalsVisibleTo() attribute for VBNET 2.0 while testing?

  - by Will Marcouiller

  I'm building an Active Directory wrapper in VBNET 2.0 (can't use later .NET) in which I have the following: IUtilisateur IGroupe IUniteOrganisation These interfaces are implemented in internal classes (Friend in VBNET), so that I want to implement a façade in order to instiate each of the interfaces with their internal classes. This will allow the architecture a better flexibility, etc. Now, I want to test these classes (Utilisateur, Groupe, UniteOrganisation) in a different project within the same solution. However, these classes are internal. I would like to be able to instantiate them without going through my façade, but only for these tests, nothing more. Here's a piece of code to illustrate it: public static class DirectoryFacade { public static IGroupe CreerGroupe() { return new Groupe(); } } // Then in code, I would write something alike: public partial class MainForm : Form { public MainForm() { IGroupe g = DirectoryFacade.CreerGroupe(); // Doing stuff with instance here... } } // My sample interface: public interface IGroupe { string Domaine { get; set; } IList<IUtilisateur> Membres { get; } } internal class Groupe : IGroupe { private IList<IUtilisateur> _membres; internal Groupe() { _membres = new List<IUtilisateur>(); } public string Domaine { get; set; } public IList<IUtilisateur> Membres { get { return _membres; } } } I heard of InternalsVisibleTo() attribute, recently. I was wondering whether it is available in VBNET 2.0/VS2005 so that I could access the assmebly's internal classes for my tests? Otherwise, how could I achieve this?

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• Editing XML file content with Python.

  - by Hooloovoo

  Hi, I am trying to use Python to read in an XML file containing some parameter names and values, e.g. ... <parameter name='par1'> <value>24</value> </parameter> <parameter name='par2'> <value>Blue/Red/Green</value> </parameter> ... and then pass it a dictionary with the parameter names {'par1':'53','par2':'Yellow/Pink/Black',...} and corresponding new values to replace the old ones in the XML file. The output should then overwrite the original XML file. At the moment I am converting the XML to a python dictionary and after some element comparison and regular expression handling, writing the output again in XML format. I am not too happy with this and was wondering whether anyone can recommend a more efficient way of doing it? Thanks.

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• Picture Box and Form Transparency

  - by Qu1nncunxIV

  Maybe I am missing something, but is it the case that when you set a pictureboxes background to transparent, all it really does is set it to the same color as the forms background? What I am trying to do is draw an animation for the benefit of this, a bouncing ball - which I paint on the form, then overlay that with a picture frame. End result should be a bouncing ball in a picture frame, I should mention that the picture frame does not have a straight edge, so it is not possible to arrange 4 picture boxes in a frame. The ball needs to vanish behind the frame to change color and then magically bounce back out. I have tried: 1.Setting the picture box background to pink and then key out the same pink, this basically cuts away everything, including that which is behind the picture box 2.Setting the picture box to transparent, this just displays the picture box background as the same color as the forms background. 3.I have tried painting the image in a rectangle, this had the same effect as drawing it in a picture box. I am not sure what I am doing wrong, I am wondering if there is any other ways I could try or if someone has made a custom control or library that supports transparency?

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• Should I re-use UI elements across view controllers?

  - by Endemic

  In the iPhone app I'm currently working on, I'd like two navigation controllers (I'll call them A and B) to have toolbars that are identical in appearance and function. The toolbar in question will look like this: [(button) (flexible-space) (label)] For posterity's sake, the label is actually a UIBarButtonItem with a custom view. My design requires that A always appear directly before B on the navigation stack, so B will never be loaded without A having been loaded. Given this layout, I started wondering, "Is it worth it to re-use A's toolbar items in B's toolbar?" As I see it, my options are: 1. Don't worry about re-use, create the toolbar items twice 2. Create the toolbar items in A and pass them to B in a custom initializer 3. Use some more obscure method that I haven't thought of to hold the toolbar constant when pushing a view controller As far as I can see, option 1 may violate DRY, but guarantees that there won't be any confusion on the off chance that (for example) the button may be required to perform two different (no matter how similar) functions for either view controller in future versions of the app. Were that to happen, options 2 or 3 would require the target-action of the button to change when B is loaded and unloaded. Even if the button were never required to perform different functions, I'm not sure what its proper target would be under option 2. All in all, it's not a huge problem, even if I have to go with option 1. I'm probably overthinking this anyway, trying to apply the dependency injection pattern where it's not appropriate. I just want to know the best practice should this situation arise in a more extreme form, like if a long chain of view controllers need to use identical (in appearance and function) UI elements.

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• Should I change $_REQUEST to $_POST

  - by Scarface

  Hey guys quick question, I have a checkbox system where a list of items can be checked and deleted on the click of a button. I currently use request and it does the job but I was wondering if $_REQUEST was some sort of security risk or improper. If anyone has any advice I would appreciate it. Should I change to $_POST? If so, what is the best way to go about it? foreach ($_REQUEST as $key=>$value) { if (substr($key,0,3)==="img") { $id = substr($key,3); if(isset($_REQUEST['Delete'])) { $sql = 'SELECT file_name,username FROM images WHERE id=?'; $stmt = $conn->prepare($sql); $result=$stmt->execute(array($id)); while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) { $image=$row['file_name']; $user=$row['username']; $myFile = "$user/images/$image"; unlink($myFile); } <input id=\"img".$id."\" name=\"img".$id."\" type=\"checkbox\">

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• Make an abstract class or use a processor?

  - by Tim Murphy

  I'm developing a class to compare two directories and run an action when a directory/file in the source directory does not exist in destination directory. Here is a prototype of the class: public abstract class IdenticalDirectories { private DirectoryInfo _sourceDirectory; private DirectoryInfo _destinationDirectory; protected abstract void DirectoryExists(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); protected abstract void DirectoryDoesNotExist(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); protected abstract void FileExists(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); protected abstract void FileDoesNotExist(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); public IdenticalDirectories(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory) { ... } public void Run() { foreach (DirectoryInfo sourceSubDirectory in _sourceDirectory.GetDirectories()) { DirectoryInfo destinationSubDirectory = this.GetDestinationDirectoryInfo(subDirectory); if (destinationSubDirectory.Exists()) { this.DirectoryExists(sourceSubDirectory, destinationSubDirectory); } else { this.DirectoryDoesNotExist(sourceSubDirectory, destinationSubDirectory); } foreach (FileInfo sourceFile in sourceSubDirectory.GetFiles()) { FileInfo destinationFile = this.GetDestinationFileInfo(sourceFile); if (destinationFile.Exists()) { this.FileExists(sourceFile, destinationFile); } else { this.FileDoesNotExist(sourceFile, destinationFile); } } } } } The above prototype is an abstract class. I'm wondering if it would be better to make the class non-abstract and have the Run method receiver a processor? eg. public void Run(IIdenticalDirectoriesProcessor processor) { foreach (DirectoryInfo sourceSubDirectory in _sourceDirectory.GetDirectories()) { DirectoryInfo destinationSubDirectory = this.GetDestinationDirectoryInfo(subDirectory); if (destinationSubDirectory.Exists()) { processor.DirectoryExists(sourceSubDirectory, destinationSubDirectory); } else { processor.DirectoryDoesNotExist(sourceSubDirectory, destinationSubDirectory); } foreach (FileInfo sourceFile in sourceSubDirectory.GetFiles()) { FileInfo destinationFile = this.GetDestinationFileInfo(sourceFile); if (destinationFile.Exists()) { processor.FileExists(sourceFile, destinationFile); } else { processor.FileDoesNotExist(sourceFile, destinationFile); } } } } What do you see as the pros and cons of each implementation?

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• What is the best way to add two strings together?

  - by Pim Jager

  I read somewehere (I thought on codinghorror) that it is bad practice to add strings together as if they are numbers, since like numbers, strings cannot be changed. Thus, adding them together creates a new string. So, I was wondering, what is the best way to add two strings together, when focusing on performance? Which of these four is better, or is there another way which is better? //Note that normally at least one of these two strings is variable $str1 = 'Hello '; $str2 = 'World!'; $output1 = $str1.$str2; //This is said to be bad $str1 = 'Hello '; $output2 = $str1.'World!'; //Also bad $str1 = 'Hello'; $str2 = 'World!'; $output3 = sprintf('%s %s', $str1, $str2); //Good? //This last one is probaply more common as: //$output = sprintf('%s %s', 'Hello', 'World!'); $str1 = 'Hello '; $str2 = '{a}World!'; $output4 = str_replace('{a}', $str1, $str2); Does it even matter?

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• Avoiding repetition with libraries that use a setup + execute model

  - by lijie

  Some libraries offer the ability to separate setup and execution, esp if the setup portion has undesirable characteristics such as unbounded latency. If the program needs to have this reflected in its structure, then it is natural to have: void setupXXX(...); // which calls the setup stuff void doXXX(...); // which calls the execute stuff The problem with this is that the structure of setupXXX and doXXX is going to be quite similar (at least textually -- control flow will prob be more complex in doXXX). Wondering if there are any ways to avoid this. Example: Let's say we're doing signal processing: filtering with a known kernel in the frequency domain. so, setupXXX and doXXX would probably be something like... void doFilter(FilterStuff *c) { for (int i = 0; i < c->N; ++i) { doFFT(c->x[i], c->fft_forward_setup, c->tmp); doMultiplyVector(c->tmp, c->filter); doFFT(c->tmp, c->fft_inverse_setup, c->x[i]); } } void setupFilter(FilterStuff *c) { setupFFT(..., &(c->fft_forward_setup)); // assign the kernel to c->filter ... setupFFT(..., &(c->fft_inverse_setup)); }

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• Maximum length of a std::basic_string<_CharT> string

  - by themoondothshine

  Hey all, I was wondering how one can fix an upper limit for the length of a string (in C++) for a given platform. I scrutinized a lot of libraries, and most of them define it arbitrarily. The GNU C++ STL (the one with experimental C++0x features) has quite a definition: size_t npos = size_t(-1); /*!< The maximum value that can be stored in a variable of type size_t */ size_t _S_max_len = ((npos - sizeof(_Rep_base))/sizeof(_CharT) - 1) / 4; /*!< Where _CharT is a template parameter; _Rep_base is a structure which encapsulates the allocated memory */ Here's how I understand the formula: The size_t type must hold the count of units allocated to the string (where each unit is of type _CharT) Theoretically, the maximum value that a variable of type size_t can take on is the total number of units of 1 byte (ie, of type char) that may be allocated The previous value minus the overhead required to keep track of the allocated memory (_Rep_base) is therefore the maximum number of units in a string. Divide this value by sizeof(_CharT) as _CharT may require more than a byte Subtract 1 from the previous value to account for a terminating character Finally, that leave the division by 4. I have absolutely no idea why! I looked at a lot of places for an explanation, but couldn't find a satisfactory one anywhere (that's why I've been trying to make up something for it! Please correct me if I'm wrong!!).

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• Having trouble using jQuery's .animate() to animate a div from left to right, right to left?

  - by Alex

  Hello, I seem to be having difficulties using jQuery .animate() to animate an absolutely positioned div from right to left on a button click, and left to right on another button click. I was wondering if you would be willing to help me understand what I'm doing wrong? Thanks. Below is my relevant CSS, HTML, and jQuery code. I can click the #moveLeft button and it wil indeed animate it to the left, but when I click the #moveRight button, nothing happens. Where am I going wrong? Thanks!! CSS #scorecardTwo { position:absolute; padding:5px; width: 300px; background-color:#E1E1E1; right:0px; top:0px; display:none; } HTML text text Left Right jQuery $("#scorecardTwo").fadeIn("slow"); $("#moveLeft").bind("click", function() { var config = { "left" : function() { return $(this).offset().left; }, "right" : function() { return $("body").innerWidth() - $K("#scorecardTwo").width(); } }; $("#scorecardTwo").css(config).animate({"left": "0px"}, "slow"); $(this).attr("disabled", "disabled"); $("#moveRight").attr("disabled", ""); }); $("#moveRight").bind("click", function() { var config = { "left" : function() { return $(this).offset().left; }, "right" : function() { return $("body").innerWidth() - $K("#scorecardTwo").width(); } }; $("#scorecardTwo").css(config).animate({"right" : "0px"}, "slow"); $(this).attr("disabled", "disabled"); $("#moveLeft").attr("disabled", ""); });

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• Simpler / more efficient method of nested if ... else flow?

  - by Scott

  I'm currently working on an emulation server for a flash-client based game, which has a "pets system", and I was wondering if there was a simpler way of going about checking the level of specified pets. Current code: public int Level { get { if (Expirience > 100) // Level 2 { if (Expirience > 200) // Level 3 { if (Expirience > 400) // Level 4 - Unsure of Goal { if (Expirience > 600) // Level 5 - Unsure of Goal { if (Expirience > 1000) // Level 6 { if (Expirience > 1300) // Level 7 { if (Expirience > 1800) // Level 8 { if (Expirience > 2400) // Level 9 { if (Expirience > 3200) // Level 10 { if (Expirience > 4300) // Level 11 { if (Expirience > 7200) // Level 12 - Unsure of Goal { if (Expirience > 8500) // Level 13 - Unsure of Goal { if (Expirience > 10100) // Level 14 { if (Expirience > 13300) // Level 15 { if (Expirience > 17500) // Level 16 { if (Expirience > 23000) // Level 17 { return 17; // Bored } return 16; } return 15; } return 14; } return 13; } return 12; } return 11; } return 10; } return 9; } return 8; } return 7; } return 6; } return 5; } return 4; } return 3; } return 2; } return 1; } } Yes, I'm aware I've misspelt Experience, I had made the mistake in a previous function and hadn't gotten around to updating everything.

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• Efficient way to call .Sum() on multiple properties

  - by SherCoder

  I have a function that uses Linq to get data from the database and then I call that function in another function to sum all the individual properties using .Sum on each individual property. I was wondering if there is an efficient way to sum all the properties at once rather than calling .Sum() on each individual property. I think the way I am doing as of right now, is very slow (although untested). public OminitureStats GetAvgOmnitureData(int? fnsId, int dateRange) { IQueryable<OminitureStats> query = GetOmnitureDataAsQueryable(fnsId, dateRange); int pageViews = query.Sum(q => q.PageViews); int monthlyUniqueVisitors = query.Sum(q => q.MonthlyUniqueVisitors); int visits = query.Sum(q => q.Visits); double pagesPerVisit = (double)query.Sum(q => q.PagesPerVisit); double bounceRate = (double)query.Sum(q => q.BounceRate); return new OminitureStats(pageViews, monthlyUniqueVisitors, visits, bounceRate, pagesPerVisit); }

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• Battery life if using GPS and background program

  - by StealthRT

  I was wondering if anyone has created an app that starts in the background and utilizes the GPS to gather the current Lat and Long every minute or so? If you have, would you please provide your battery times? As in, how long does your phone last until its all out of juice from just running that background app with standard cell phone programs. I'm trying to see if it would be worth the time to create an app for myself but if i work for 8 hours and dont have a way of charging my phone during that time then i dont want to be going home and it shut down on me since my app i would create works at my house. I need the app to work since it will see when i am in range of my home (from the GPS) and then send commands to my server at the house from my phone. So thats why it would need to be able to stay in the background doing a check every 1 minute or so. Or only turn on the GPS (Is is doable with iOS? & Android?) whenever its after 5pm each day so that it will minimize the load on the battery?!? Any help or suggestions would be great! Thanks!

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• C# Passing objects and list of objects by reference

  - by David Liddle

  I have a delegate that modifies an object. I pass an object to the delegate from a calling method, however the calling method does not pickup these changes. The same code works if I pass a List as the object. I thought all objects were passed by reference so any modifications would be reflected in the calling method? I can modify my code to pass a ref object to the delegate but am wondering why this is necessary? public class Binder { protected delegate int MyBinder<T>(object reader, T myObject); public void BindIt<T>(object reader, T myObject) { //m_binders is a hashtable of binder objects MyBinder<T> binder = m_binders["test"] as MyBinder<T>; int i = binder(reader, myObject); } } public class MyObjectBinder { public MyObjectBinder() { m_delegates["test"] = new MyBinder<MyObject>(BindMyObject); } private int BindMyObject(object reader, MyObject obj) { //make changes to obj in here } } ///calling method in some other class public void CallingMethod() { MyObject obj = new MyObject(); MyBinder binder = new MyBinder(); binder.BindIt(myReader, obj); //don't worry about myReader //obj should show reflected changes }

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• Displaying Query Results Horizontally

  - by AndyD273

  I am wondering if it is possible to take the results of a query and return them as a CSV string instead of as a column of cells. Basically, we have a table called Customers, and we have a table called CustomerTypeLines, and each Customer can have multiple CustomerTypeLines. When I run a query against it, I run into problems when I want to check multiple types, for instance: Select * from Customers a Inner Join CustomerTypeLines b on a.CustomerID = b.CustomerID where b.CustomerTypeID = 14 and b.CustomerTypeID = 66 ...returns nothing because a customer can't have both on the same line, obviously. In order to make it work, I had to add a field to Customers called CustomerTypes that looks like ,14,66,67, so I can do a Where a.CustomerTypes like '%,14,%' and a.CustomerTypes like '%,66,%' which returns 85 rows. Of course this is a pain because I have to make my program rebuild this field for that Customer each time the CustomerTypeLines table is changed. It would be nice if I could do a sub query in my where that would do the work for me, so instead of returning the results like: 14 66 67 it would return them like ,14,66,67, Is this possible?

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• How to approach socket programming between C# -> Java (Android)

  - by Alex

  I've recently knocked up a server/client app for Windows & Android that allows one to send a file from Windows to an android phone over a socket connection. It works great for a single file but trying to send multiple files over in a single stream is causing me problems. I've also realised that aside from the binary data, I will need to send messages over the socket to indicate error states and other application messages. I have little experience with network programming and and wondering what is the best way forward. Basically the C# server side of the app just goes into a listening state and uses Socket.SendFile to transmit the file. On Android I use the standard Java Socket.getInputStream() to receive the file. That works great for a single file transfer, but how should I handle multiple files and error/messaging information? Do I need to use a different socket for each file? Should I be using a higher level framework to handle this or can I send everything over the single socket? Any other suggestions for frameworks or learning materials?

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• Div Container Cleanup?

  - by Nto

  Just wondering if its possible to cleanup (less code needed to do the same thing) making this div container. Basically it's just a div with a background image however the top & bottom of the div have rounded graphical corners which is why I have a top, middle, and bottom div inside the container div. <div class="fbox"> <div class="ftop"></div> <div class="fmid"> Fullbox Text Goes Here </div> <div class="fbot"></div> </div> Css: .fbox { width: 934px; margin: 0 auto; opacity: 0.70; } .ftop { width: 934px; background:url(../images/cb/full.png) no-repeat 0 -34px; height: 17px; margin:0 } .fmid { width: 894px; padding-left: 20px; padding-right: 20px; background:url(../images/cb/fullmid.png) repeat-y; min-height: 50px; margin:0 } .fbot { width: 934px; background:url(../images/cb/full.png) no-repeat 0 -17px; height: 17px; margin:0 } Outcome: http://img709.imageshack.us/img709/6681/fbox.jpg

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• Moq basic questions

  - by devoured elysium

  I made the following test for my class: var mock = new Mock<IRandomNumberGenerator>(); mock.Setup(framework => framework.Generate(0, 50)) .Returns(7.0); var rnac = new RandomNumberAverageCounter(mock.Object, 1, 100); rnac.Run(); double result = rnac.GetAverage(); Assert.AreEqual(result, 7.0, 0.1); The problem here was that I changed my mind about what range of values Generate(int min, int max) would use. So in Mock.Setup() I defined the range as from 0 to 50 while later I actually called the Generate() method with a range from 1 to 100. I ran the test and it failed. I know that that is what it's supposed to happen but I was left wondering if isn't there a way to launch an exception or throw in a message when trying to run the method with wrong params. Also, if I want to run this Generate() method 10 times with different values (let's say, from 1 to 10), will I have to make 10 mock setups or something, or is there a special method for it? The best I could think of is this (which isn't bad, I'm just asking if there is other better way): for (int i = 1; i < 10; ++i) { mock.Setup(framework => framework.Generate(1, 100)) .Returns((double)i); }

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• The cross-thread usage of "HttpContext.Current" property and related things

  - by smwikipedia

  I read from < Essential ASP.NET with Examples in C# the following statement: Another useful property to know about is the static Current property of the HttpContext class. This property always points to the current instance of the HttpContext class for the request being serviced. This can be convenient if you are writing helper classes that will be used from pages or other pipeline classes and may need to access the context for whatever reason. By using the static Current property to retrieve the context, you can avoid passing a reference to it to helper classes. For example, the class shown in Listing 4-1 uses the Current property of the context to access the QueryString and print something to the current response buffer. Note that for this static property to be correctly initialized, the caller must be executing on the original request thread, so if you have spawned additional threads to perform work during a request, you must take care to provide access to the context class yourself. I am wondering about the root cause of the bold part, and one thing leads to another, here is my thoughts: We know that a process can have multiple threads. Each of these threads have their own stacks, respectively. These threads also have access to a shared memory area, the heap. The stack then, as I understand it, is kind of where all the context for that thread is stored. For a thread to access something in the heap it must use a pointer, and the pointer is stored on its stack. So when we make some cross-thread calls, we must make sure that all the necessary context info is passed from the caller thread's stack to the callee thread's stack. But I am not quite sure if I made any mistake. Any comments will be deeply appreciated. Thanks. ADD Here the stack is limited to user stack.

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• swap! alter and alike

  - by mekka

  Hello, I am having a problem understanding how these functions update the underlying ref, atom etc. The docs say: (apply f current-value-of-identity args) (def one (atom 0)) (swap! one inc) ;; => 1 So I am wondering how it got "expanded" to the apply form. It's not mentioned what exactly 'args' in the apply form is. Is it a sequence of arguments or are these separate values? Was it "expanded" to: (apply inc 0) ; obviously this wouldnt work, so that leaves only one possibility (apply inc 0 '()) (swap! one + 1 2 3) ;; #=> 7 Was it: (apply + 1 1 2 3 '()) ;or (apply + 1 [1 2 3]) (def two (atom [])) (swap! two conj 10 20) ;; #=> [10 20] Was it: (apply conj [] [10 20]) ;or (apply conj [] 10 20 '()) If I swap with a custom function like this: (def three (atom 0)) (swap! three (fn [current elem] (println (class elem))) 10) ;;#=> java.Lang.Integer Which means that the value '10' doesnt magically get changed into a seq '(10) and leads me to the conclusion, that it gets "expanded" to: (apply f current-value-of-identity arg1 arg2 arg3... '()) Is that a correct assumption and the docs are simply lacking a better description?

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• Java: GatheringByteChannel advantages?

  - by Jason S

  I'm wondering when the GatheringByteChannel's write methods (taking in an array of ByteBuffers) have advantages over the "regular" WritableByteChannel write methods. I tried a test where I could use the regular vs. the gathering write method on a FileChannel, with approx 400KB/sec total in ByteBuffers of between 23-27 bytes in length in both cases. Gathering writes used an array of 64. The regular method used up approx 12% of my CPU, and the gathering method used up approx 16% of my CPU (worse than the regular method!) This tells me it's NOT useful to use gathering writes on a FileChannel around this range of operating parameters. Why would this be the case, and when would you ever use GatheringByteChannel? (on network I/O?) Relevant differences here: public void log(Queue<Packet> packets) throws IOException { if (this.gather) { int Nbuf = 64; ByteBuffer[] bbufs = new ByteBuffer[Nbuf]; int i = 0; Packet p; while ((p = packets.poll()) != null) { bbufs[i++] = p.getBuffer(); if (i == Nbuf) { this.fc.write(bbufs); i = 0; } } if (i > 0) { this.fc.write(bbufs, 0, i); } } else { Packet p; while ((p = packets.poll()) != null) { this.fc.write(p.getBuffer()); } } }

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• Is it possible to get a truly unique id for a particular JVM instance?

  - by Uri

  I need a way to uniquely and permanently identify an instance of the JVM from within Java code running in that JVM. That is, if I have two JVMs running at the same time on the same machine, each is distinguishable. It is also distinguishable from running JVMs on other machines and from future executions on the same machine even if the process id is reused. I figure I could implement something like this by identifying the start time, the machine MAC, and the process id, and combining them in some way. I'm wondering if there is some standard way to achieve this. Update: I see that everyone recommended a UUID for the entire session. That seems like a good idea though possibly a little too heavyweight. Here is my problem though: I want to use the JVM id to create multiple unique identifiers in each JVM execution that somehow incorporate the JVM instance. My understanding is that you shouldn't really mix other numbers into a UUID because uniqueness is no longer guaranteed. An alternative is to make the UUID into a string and chain it, but then it becomes too long. Any ideas on overcoming this?

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