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  • Keeping dates in order when using date_select and discarding year in Rails?

    - by MikeH
    My app has users who have seasonal products. When a user selects a product, we allow him to also select the product's season. We accomplish this by letting him select a start date and an end date for each product. We're using date_select to generate two sets of drop-downs: one for the start date and one for the end date. Including years doesn't make sense for our model. So we're using the option: discard_year => true To explain our problem, consider that our products are apples. Vendor X carries apples every year from September to January. Years are irrelevant here, and that's why we're using discard_year => true. However, while the specific years are irrelevant, the relative point in time from the start date to the end date is relevant. This is where our problem arises. When you use discard_year => true, Rails does set a year in the database, it just doesn't appear in the views. Rails sets all the years to 0001 in our app. Going back to our apple example, this means that the database now thinks the user has selected September 0001 to January 0001. This is a problem for us for a number of reasons. To solve this, the logic that I need to implement is the following: - If season_start month/date is before season_end month/date, then standard Rails approach is fine. - But, if season_start month/date is AFTER season_end month/date, then I need to dynamically update the database field such that the year for season_end is equal to the year for season_start + 1. My best guess is that I would create a custom method that runs as an after_save or after_update in my products model. But I'm not really sure how to do this. Ideas? Anybody ever had this issue? Thanks!

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  • NSCollectionView: Can the same object not be in the array more than once or is this a bug?

    - by Sean
    I may be doing this all wrong, but I thought I was on the right track until I hit this little snag. Basically I was putting together a toy using NSCollectionView and trying to understand how to hook that all up using IB. I have a button which will add a couple of strings to the NSArrayController: The first time I press this button, my strings appear in the collection view as expected: The second time I press the button, the views scroll down and room is made - but the items don't appear to get added. I just see blank space: The button is implemented as follows (controller is a pointer to the NSArrayController I added in IB): - (IBAction)addStuff:(id)control { [controller addObjects:[NSArray arrayWithObjects:@"String 1",@"String 2",@"String 3",nil]]; } I'm not sure what I'm doing wrong. Rather than try to explain all the connections/binds/etc, if you need more info, I'd be grateful if you could just take a quick look at the toy project itself. UPDATE: After more experimentation as suggested by James Williams, it seems the problem stems from having multiple objects with the same memory address in the array. This confuses either NSArrayController or NSCollectionView (not sure which). Changing my addStuff: to this resulted in the behavior I originally expected: [controller addObjects:[NSArray arrayWithObjects:[NSMutableString stringWithString:@"String 1"],[NSMutableString stringWithString:@"String 2"],[NSMutableString stringWithString:@"String 3"],nil]]; So the question now, I guess, is if this is a bug I should report to Apple or if this is intended/documented behavior and I just missed it?

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  • Creation of Objects: Constructors or Static Factory Methods

    - by Rachel
    I am going through Effective Java and some of my things which I consider as standard are not suggested by the book, for instance creation of object, I was under the impression that constructors are the best way of doing it and books says we should make use of static factory methods, I am not able to few some advantages and so disadvantages and so am asking this question, here are the benefits of using it. Advantages: One advantage of static factory methods is that, unlike constructors, they have names. A second advantage of static factory methods is that, unlike constructors, they are not required to create a new object each time they’re invoked. A third advantage of static factory methods is that, unlike constructors, they can return an object of any subtype of their return type. A fourth advantage of static factory methods is that they reduce the verbosity of creating parameterized type instances. I am not able to understand this advantage and would appreciate if someone can explain this point Disadvantages: The main disadvantage of providing only static factory methods is that classes without public or protected constructors cannot be subclassed. A second disadvantage of static factory methods is that they are not readily distinguishable from other static methods.I am not getting this point and so would really appreciate some explanation. Reference: Effective Java, Joshua Bloch, Edition 2, pg: 5-10 Also, How to decide to use whether to go for Constructor or Static Factory Method for Object Creation ?

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  • C# Breakpoint Weirdness

    - by Dan
    In my program I've got two data files A and B. The data in A is static and the data in B refers back to the data in A. In order to make sure the data in B is invalidated when A is changed, I keep an identifier for each of the links which is a long byte-string identifying the data. I get this string using BitConverter on some of the important properties. My problem is that this scheme isn't working. I save the identifiers initially, and with I reload (with the exact same data in A) the identifiers don't match anymore. It seems the bit converter gives different results when I go to save. The really weird thing about it is, if I place a breakpoint in the save code, I can see the identifier it's writing to the file is fine, and the next load works. If I don't place a breakpoint and say print the identifiers to console instead, they're totally different. It's like when my program is running at full-speed the CPU messes up some instructions. This isn't the first time something like this happens to me. I've seen it in other projects. What gives? Has anyone every experienced this kind of debugging weirdness? I can't explain how stopping the program and not stopping it can change the output. Also, it's not a hardware problem because this happens on my laptop as well.

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  • Why doesn't java.util.Set have get(int index)?

    - by Marty Pitt
    I'm sure there's a good reason, but could someone please explain why the java.util.Set interface lacks get(int Index), or any similar get() method? It seems that sets are great for putting things into, but I can't find an elegant way of retrieving a single item from it. If I know I want the first item, I can use set.iterator().next(), but otherwise it seems I have to cast to an Array to retrieve an item at a specific index? What are the appropriate ways of retrieving data from a set? (other than using an iterator) I'm sure the fact that it's excluded from the API means there's a good reason for not doing this -- could someone please enlighten me? EDIT: Some extremely great answers here, and a few saying "more context". The specific scneario was a dbUnit test, where I could reasonalby assert that the returned set from a query had only 1 item, and I was trying to access that item. However, the question is more valid without the scenario, as it remains more focussed : What's the difference between set & list. Thanks to all for the fantastic answers below.

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  • Adding <tr> from repeater's ItemDataBound Event

    - by nemiss
    My repeater's templates generate a table, where each item is a table row. When a very very specific condition is met (itemdata), I want to add an additional row to the table from this event. How can I do that? protected void rptData_ItemDataBound(object sender, RepeaterItemEventArgs e) { if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem) { bool tmp = bool.Parse(DataBinder.Eval(e.Item.DataItem, "somedata").ToString()); if (!tmp && e.Item.ItemIndex != 0) { //Add row after this item } } } I can use e.Item.Controls.Add() and add TableRow but for that I need to locate a table right? How can I solve that? UPDATE I will explain now why I need this: I am creating a sort of message board, where data entries are displayed in a tabled style. The first items in the table are "important" items after those items, i want to add this row. I could solved it using 2 repeaters, where the first repeater will be bounded to pinned items, and the second repeater will be bounded to refular items. But I don't want to have to repeaters nor I want to complex the business logic for separating the fetched data to pinned and not-pinned collection. I think the best opton is to do it "onfly", using one repeater and one datasource.

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  • Dynamic/Generic ViewModelBase?

    - by Shimmy
    I am learning MVVM now and I understand few things (more than but few are here..): Does every model potentially exposed (thru a VM) to the View is having a VM? For example, if I have a Contact and Address entity and each contact has an Addresses (many) property, does it mean I have to create a ContactViewModel and an AddressViewModel etc.? Do I have to redeclare all the properties of the Model again in the ViewModel (i.e. FirstName, LastName blah blah)? why not have a ViewModelBase and the ContactViewMode will be a subclass of ViewModelBase accessing the Entity's properties itself? and if this is a bad idea that the View has access to the entity (please explain why), then why not have the ViewModelBase be a DynamicObject (view the Dictionary example @ the link page), so I don't have to redeclare all the properties and validation over and over in the two tiers (M & VM) - because really, the View is anyway accessing the ViewModel's fields via reflection anyway. I think MVVM was the hardest technology I've ever learned. it doesn't have out-the-box support and there are to many frameworks and methods to achieve it, and in the other hand there is no arranged way to learn it (as MVC for instance), learning MVVM means browsing and surfing around trying to figure out what's better. Bottom line, what I mean by this section is please go and vote to MSFT to add MVVM support in the BCL and generators for VMs and Vs according to the Ms. Thanks

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  • Unit Testing Private Method in Resource Managing Class (C++)

    - by BillyONeal
    I previously asked this question under another name but deleted it because I didn't explain it very well. Let's say I have a class which manages a file. Let's say that this class treats the file as having a specific file format, and contains methods to perform operations on this file: class Foo { std::wstring fileName_; public: Foo(const std::wstring& fileName) : fileName_(fileName) { //Construct a Foo here. }; int getChecksum() { //Open the file and read some part of it //Long method to figure out what checksum it is. //Return the checksum. } }; Let's say I'd like to be able to unit test the part of this class that calculates the checksum. Unit testing the parts of the class that load in the file and such is impractical, because to test every part of the getChecksum() method I might need to construct 40 or 50 files! Now lets say I'd like to reuse the checksum method elsewhere in the class. I extract the method so that it now looks like this: class Foo { std::wstring fileName_; static int calculateChecksum(const std::vector<unsigned char> &fileBytes) { //Long method to figure out what checksum it is. } public: Foo(const std::wstring& fileName) : fileName_(fileName) { //Construct a Foo here. }; int getChecksum() { //Open the file and read some part of it return calculateChecksum( something ); } void modifyThisFileSomehow() { //Perform modification int newChecksum = calculateChecksum( something ); //Apply the newChecksum to the file } }; Now I'd like to unit test the calculateChecksum() method because it's easy to test and complicated, and I don't care about unit testing getChecksum() because it's simple and very difficult to test. But I can't test calculateChecksum() directly because it is private. Does anyone know of a solution to this problem?

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  • heap sort function explanation needed

    - by Codeguru
    Hello, Can someone clearly explain me how these functions of heap sort are working?? void heapSort(int numbers[], int array_size) { int i, temp; for (i = (array_size / 2)-1; i >= 0; i--) siftDown(numbers, i, array_size); for (i = array_size-1; i >= 1; i--) { temp = numbers[0]; numbers[0] = numbers[i]; numbers[i] = temp; siftDown(numbers, 0, i-1); } } void siftDown(int numbers[], int root, int bottom) { int done, maxChild, temp; done = 0; while ((root*2 <= bottom) && (!done)) { if (root*2 == bottom) maxChild = root * 2; else if (numbers[root * 2] > numbers[root * 2 + 1]) maxChild = root * 2; else maxChild = root * 2 + 1; if (numbers[root] < numbers[maxChild]) { temp = numbers[root]; numbers[root] = numbers[maxChild]; numbers[maxChild] = temp; root = maxChild; } else done = 1; } }

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  • GNU Make - Dependencies on non program code

    - by Tim Post
    A requirement for a program I am writing is that it must be able to trust a configuration file. To accomplish this, I am using several kinds of hashing algorithms to generate a hash of the file at compile time, this produces a header with the hashes as constants. Dependencies for this are pretty straight forward, my program depends on config_hash.h, which has a target that produces it. The makefile looks something like this : config_hash.h: $(SH) genhash config/config_file.cfg > $(srcdir)/config_hash.h $(PROGRAM): config_hash.h $(PROGRAM_DEPS) $(CC) ... ... ... I'm using the -M option to gcc, which is great for dealing with dependencies. If my header changes, my program is rebuilt. My problem is, I need to be able to tell if the config file has changed, so that config_hash.h is re-generated. I'm not quite sure how explain that kind of dependency to GNU make. I've tried listing config/config_file.cfg as a dependency for config_hash.h, and providing a .PHONY target for config_file.cfg without success. Obviously, I can't rely on the -M switch to gcc to help me here, since the config file is not a part of any object code. Any suggestions? Unfortunately, I can't post much of the Makefile, or I would have just posted the whole thing.

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  • WPF ContextMenu bind some property to another property of the same control

    - by bebicasoft
    I have a ContextMenu and a ColumnHeaderStyle defined in Window.Resource section witch i use-it to a DataGrid ColumnHeader. My code is something like this: <ContextMenu x:Key="cm_columnHeaderMenu"/> <Style x:Key="DefaultColumnHeaderStyle" TargetType="{x:Type DataGridColumnHeader}"> <Setter Property="ContextMenu" Value="{StaticResource cm_columnHeaderMenu}" /> </Style> <DataGrid Grid.Column="2" Grid.Row="1" x:Name="dgridFiles" IsReadOnly="True" ColumnHeaderStyle="{StaticResource DefaultColumnHeaderStyle}"> I want to know if I can (and if the answer it true, then HOW I could do it) bind the ContextMenu Visibility property to same control ContextMenu Items.Count>0 property. Initially based on some other treeView control selections made there shoud be no items in the context menu, but i wish to add dinamically items in ContextMenu based on selection in treeView. This part is done, the context has those items. On some selections there are no-items, but still on the grid it appears an empty ContextMenu. So I believe the easiest part it would be to bind the Visibility to Items.Count property of the same control. Sorry if my english is not good enought, I'll try to explain better if i didnt make clear 1st time.

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  • Is there a max recommended size on bundling js/css files due to chunking or packet loss?

    - by George Mauer
    So we all have heard that its good to bundle your javascript. Of course it is, but it seems to me that the story is too simple. See if my logic makes sense here. Obviously fewer HTTP requests is fewer round trips and hence better. However - and I don't know much about bare http - aren't http responses sent in chunks? And if a file is larger than one of those chunks doesn't it have to be downloaded as multiple (possibly synchronous?) round trips? As opposed to this, several requests for files just under the chunking size would arrive much quicker since modern web browsers download resources like javascripts in parallel. Even if chunking is not an issue, it seems like there would be some max recommended size just due to likelyhood of packet loss alone since a bundled file must wait till it is entirely downloaded to execute, versus the more lenient native rule that scripts must execute in order. Obviously there's also matters of browser caching and code volatility to consider but can someone confirm this or explain why I'm off base? Does anyone have any numbers to put to it?

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  • What are the differences between mapping,binding and parsing?

    - by sfrj
    I am starting to learn web-services in java EE6. I did web development before, but never nothing related to web services. All is new to me and the books and the tutorials i find in the web are to technical. I started learning about .xsd schemas and also .xml. In that topic i feel confident, i understand what are the schemas used for and what validation means. Now my next step is learning about JAX-B(Java Api for XML Binding). I rode some about it and i did also some practice in my IDE. But i have lots of basic doubts, that make me stuck and cannot feel confident to continue to the next topic. Ill appreciate a lot if someone could explain me well my doubts: What does it mean mapping and what is a mapping tool? What does it mean binding and what is a binding tool? What does it mean parsing and what is a parsing tool? How is JAX-B related to mapping,binding and parsing? I am seeking for a good answer built by you, not just a copy paste from google(Ive already been online a few hours and only got confused).

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  • Calculate location and number of intersections between multiple date/time ranges?

    - by Patricker
    I need to calculate the location of intersections between multiple date ranges, and the number of overlapping intersections. Then I need to show which date/time ranges overlap each of those intersecting sections. It is slightly more complicated than that so I'll do my best to explain by providing an example. I am working in VB.Net, but C# examples are acceptable as well as I work in both. We have several high risk tasks that involve the same system. Below I have three example jobs named HR1/2/3/4 with start and end date/times. HR1 {1/6/2010 10:00 - 1/6/2010 15:00} HR2 {1/6/2010 11:00 - 1/6/2010 18:00} HR3 {1/6/2010 12:00 - 1/6/2010 14:00} HR4 {1/6/2010 18:00 - 1/6/2010 20:00} What I want the end result to be is shown below. I am having trouble describing it any way but by example. HRE1 {1/6/2010 10:00 - 1/6/2010 11:00} - Intersects 1 {End Time Split 1, for readability only, not needed in solution} HRE1 {1/6/2010 11:00 - 1/6/2010 12:00} - Intersects 2 HRE2 {1/6/2010 11:00 - 1/6/2010 12:00} - Intersects 2 {End Time Split 2, for readability only, not needed in solution} HRE1 {1/6/2010 12:00 - 1/6/2010 14:00} - Intersects 3 HRE2 {1/6/2010 12:00 - 1/6/2010 14:00} - Intersects 3 HRE3 {1/6/2010 12:00 - 1/6/2010 14:00} - Intersects 3 {End Time Split 3, for readability only, not needed in solution} HRE1 {1/6/2010 14:00 - 1/6/2010 15:00} - Intersects 2 HRE2 {1/6/2010 14:00 - 1/6/2010 15:00} - Intersects 2 {End Time Split 4, for readability only, not needed in solution} HRE2 {1/6/2010 15:00 - 1/6/2010 18:00} - Intersects 1 {End Time Split 5, for readability only, not needed in solution} HR4 {1/6/2010 18:00 - 1/6/2010 20:00} - Intersects 1 Any help would be greatly appreciated.

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  • questions on nfa and dfa..

    - by Loop
    Hi Guys... Hope you help me with this one.... I have a main question which is ''how to judge whether a regular expression will be accepted by NFA and/or DFA? For eg. My question says that which of the regular expressions are equivalent? explain... 1.(a+b)*b(a+b)*b(a+b)* 2.a*ba*ba* 3.a*ba*b(a+b)* do we have to draw the NFA and DFA and then find through minimisation algorithm? if we do then how do we come to know that which regular expression is accepted by NFA/DFA so that we can begin with the answer? its so confusing.... Second is a very similar one, the question asks me to show that the language (a^nb^n|n1} is not accepted by DFA...grrrrr...how do i know this? (BTW this is a set of all strings of where a number of a's is followed by the same number of b's).... I hope I explained clearly well....

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  • C to Assembly code - what does it mean

    - by Smith
    I'm trying to figure out exactly what is going on with the following assembly code. Can someone go down line by line and explain what is happening? I input what I think is happening (see comments) but need clarification. .file "testcalc.c" .section .rodata.str1.1,"aMS",@progbits,1 .LC0: .string "x=%d, y=%d, z=%d, result=%d\n" .text .globl main .type main, @function main: leal 4(%esp), %ecx // establish stack frame andl $-16, %esp // decrement %esp by 16, align stack pushl -4(%ecx) // push original stack pointer pushl %ebp // save base pointer movl %esp, %ebp // establish stack frame pushl %ecx // save to ecx subl $36, %esp // alloc 36 bytes for local vars movl $11, 8(%esp) // store 11 in z movl $6, 4(%esp) // store 6 in y movl $2, (%esp) // store 2 in x call calc // function call to calc movl %eax, 20(%esp) // %esp + 20 into %eax movl $11, 16(%esp) // WHAT movl $6, 12(%esp) // WHAT movl $2, 8(%esp) // WHAT movl $.LC0, 4(%esp) // WHAT?!?! movl $1, (%esp) // move result into address of %esp call __printf_chk // call printf function addl $36, %esp // WHAT? popl %ecx popl %ebp leal -4(%ecx), %esp ret .size main, .-main .ident "GCC: (Ubuntu 4.3.3-5ubuntu4) 4.3.3" .section .note.GNU-stack,"",@progbits Original code: #include <stdio.h> int calc(int x, int y, int z); int main() { int x = 2; int y = 6; int z = 11; int result; result = calc(x,y,z); printf("x=%d, y=%d, z=%d, result=%d\n",x,y,z,result); }

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  • Getting User input with Scanner

    - by Giannis
    I am trying to have a scanner take input in a loop. Once the user wants to finish he can exit this loop. I have tried many different ways to do it but there is always some problem. This is the code: Scanner sc = new Scanner(System.in); System.out.println("Continue?[Y/N]"); while (sc.hasNext()&& (sc.next().equals("Y"))) { System.out.println("Enter first name"); String name = sc.nextLine(); System.out.println("Enter surname"); String surname = sc.nextLine(); . . . System.out.println("Continue?[Y/N]"); } } The problem with the code above, which also happens on different methods I tried, is that when the user types Y, the scanner will skip the first input for first name,and jump to the surname. If the user types N the loop stops correctly. Someone can explain the reason this happens, and how to overcome using scanner class? p.s: Doing something like while(sc.nextLine().equals("Y")), will cause the loop to terminate before getting input from user after first run of the loop.

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  • How to add deploy.jar to classpath?

    - by dma_k
    I am facing the problem: I need to add ${java.home}/lib/deploy.jar JAR file to classpath in the runtime (dynamically from java). The solution with Thread#setContextClassLoader(ClassLoader) (mentioned here) does not work because of this bug (if somebody can explain what is really a problem – you are welcome). The solution with -Xbootclasspath/a:"%JAVA_HOME%/jre/lib/deploy.jar" does not work well for me, because I want to have "pure executable jar" as a deliverable: no wrapping scripts please (more over %JAVA_HOME% may not be defined in user's environment in Windows for example, plus I need to write a script per platform) The solution with merging deploy.jar file into my deliverable works only if I make a build on Windows platform. Unfortunately, when the deliverable is produced on build server running on Linux, I got Linux-dependant JAR, which does not execute on Windows – it fails with the trace below. I have read How the Java Launcher Finds Classes and Java programming dynamics: Java classes and class loading articles but I've got no extra ideas, how to correctly handle this situation. Any advices or solutions are very welcomed. Trace: java.lang.NoClassDefFoundError: Could not initialize class com.sun.deploy.config.Config at com.sun.deploy.net.proxy.UserDefinedProxyConfig.getBrowserProxyInfo(UserDefinedProxyConfig.java:43) at com.sun.deploy.net.proxy.DynamicProxyManager.reset(DynamicProxyManager.java:235) at com.sun.deploy.net.proxy.DeployProxySelector.reset(DeployProxySelector.java:59) ... java.lang.NullPointerException at com.sun.deploy.net.proxy.DynamicProxyManager.getProxyList(DynamicProxyManager.java:63) at com.sun.deploy.net.proxy.DeployProxySelector.select(DeployProxySelector.java:166)

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  • C# iterator is executed twice when composing two IEnumerable methods

    - by achristoph
    I just started learning about C# iterator but got confused with the flow of the program after reading the output of the program. The foreach with uniqueVals seems to be executed twice. My understanding is that the first few lines up to the line before "Nums in Square: 3" should not be there. Can anyone help to explain why this happens? The output is: Unique: 1 Adding to uniqueVals: 1 Unique: 2 Adding to uniqueVals: 2 Unique: 2 Unique: 3 Adding to uniqueVals: 3 Nums in Square: 3 Unique: 1 Adding to uniqueVals: 1 Square: 1 Number returned from Unique: 1 Unique: 2 Adding to uniqueVals: 2 Square: 2 Number returned from Unique: 4 Unique: 2 Unique: 3 Adding to uniqueVals: 3 Square: 3 Number returned from Unique: 9 static class Program { public static IEnumerable<T> Unique<T>(IEnumerable<T> sequence) { Dictionary<T, T> uniqueVals = new Dictionary<T, T>(); foreach (T item in sequence) { Console.WriteLine("Unique: {0}", item); if (!uniqueVals.ContainsKey(item)) { Console.WriteLine("Adding to uniqueVals: {0}", item); uniqueVals.Add(item, item); yield return item; Console.WriteLine("After Unique yield: {0}", item); } } } public static IEnumerable<int> Square(IEnumerable<int> nums) { Console.WriteLine("Nums in Square: {0}", nums.Count()); foreach (int num in nums) { Console.WriteLine("Square: {0}", num); yield return num * num; Console.WriteLine("After Square yield: {0}", num); } } static void Main(string[] args) { var nums = new int[] { 1, 2, 2, 3 }; foreach (int num in Square(Unique(nums))) Console.WriteLine("Number returned from Unique: {0}", num); Console.Read(); } }

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  • Design: How to declare a specialized memory handler class

    - by Michael Dorgan
    On an embedded type system, I have created a Small Object Allocator that piggy backs on top of a standard memory allocation system. This allocator is a Boost::simple_segregated_storage< class and it does exactly what I need - O(1) alloc/dealloc time on small objects at the cost of a touch of internal fragmentation. My question is how best to declare it. Right now, it's scope static declared in our mem code module, which is probably fine, but it feels a bit exposed there and is also now linked to that module forever. Normally, I declare it as a monostate or a singleton, but this uses the dynamic memory allocator (where this is located.) Furthermore, our dynamic memory allocator is being initialized and used before static object initialization occurs on our system (as again, the memory manager is pretty much the most fundamental component of an engine.) To get around this catch 22, I added an extra 'if the small memory allocator exists' to see if the small object allocator exists yet. That if that now must be run on every small object allocation. In the scheme of things, this is nearly negligable, but it still bothers me. So the question is, is there a better way to declare this portion of the memory manager that helps decouple it from the memory module and perhaps not costing that extra isinitialized() if statement? If this method uses dynamic memory, please explain how to get around lack of initialization of the small object portion of the manager.

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  • Serializing and deserializing a map with key as string

    - by Grace K
    Hi! I am intending to serialize and deserialize a hashmap whose key is a string. From Josh Bloch's Effective Java, I understand the following. P.222 "For example, consider the case of a harsh table. The physical representation is a sequence of hash buckets containing key-value entries. Which bucket an entry is placed in is a function of the hash code of the key, which is not, in general guaranteed to be the same from JVM implementation to JVM implementation. In fact, it isn't even guranteed to be the same from run to run on the same JVM implementation. Therefore accepting the default serialized form for a hash table would constitute a serious bug. Serializing and deserializing the hash table could yield an object whose invariants were seriously corrupt." My questions are: 1) In general, would overriding the equals and hashcode of the key class of the map resolve this issue and the map can be correctly restored? 2) If my key is a String and the String class is already overriding the hashCode() method, would I still have problem described above. (I am seeing a bug which makes me think this is probably still a problem even though the key is String with overriding hashCode.) 3)Previously, I get around this issue by serializing an array of entries (key, value) and when deserializing I would reconstruct the map. I am wondering if there is a better approach. 4) If the answers to question 1 and 2 are that I still can't be guaranteed. Could someone explain why? If the hashCodes are the same would they go to the same buckets across JVMs? Thanks, Grace

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  • "One or more breakpoints cannot be set and have been disabled. Execution will stop at the beginning

    - by sam
    I set a breakpoint in my code in Visual-C++, but when I run, I see the error mentioned in the title. I know this question has been asked before on Stack Overflow (http://stackoverflow.com/questions/657470/breakpoints-cannot-be-set-and-have-been-disabled-problem), but none of the answers there fully explained the problem I'm seeing. The closest I can see is something about the linker, but I don't understand that - so if someone could explain in more detail that would be great. In my case, I have 2 projects in Visual C++ - the production dsw, and the test code dsw. I have loaded and rebuilt both dsws in debug mode. I want a breakpoint in the production code, which is run via the test scripts. My issue is I get the error message when I run the test code, because the break point is in the production code, which isn't loaded up when the test starts. Near the beginning of the test script there is a mytest_initialize() command. I imagine this goes off and loads up the production dll. Once this line has executed, I can put the breakpoint in my production code and run until I hit it. But it's quite annoying to have to run to this line, set the breakpoint and continue every time I want to run the test. So I think the problem is Visual C++ doesn't realise the two projects are related. Is this a linker issue? What does the linker do and what settings should I change to make this work? Thanks in advance. Apologies if instead I should be appending this question to the existing one, this is my first post so not quite sure how this should work.

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  • Using an SHA1 with Microsoft CAPI

    - by Erik Jõgi
    I have an SHA1 hash and I need to sign it. The CryptSignHash() method requires a HCRYPTHASH handle for signing. I create it and as I have the actual hash value already then set it: CryptCreateHash(cryptoProvider, CALG_SHA1, 0, 0, &hash); CryptSetHashParam(hash, HP_HASHVAL, hashBytes, 0); The hashBytes is an array of 20 bytes. However the problem is that the signature produced from this HCRYPTHASH handle is incorrect. I traced the problem down to the fact that CAPI actually doesn't use all 20 bytes from my hashBytes array. For some reason it thinks that SHA1 is only 4 bytes. To verify this I wrote this small program: HCRYPTPROV cryptoProvider; CryptAcquireContext(&cryptoProvider, NULL, NULL, PROV_RSA_FULL, 0); HCRYPTHASH hash; HCRYPTKEY keyForHash; CryptCreateHash(cryptoProvider, CALG_SHA1, keyForHash, 0, &hash); DWORD hashLength; CryptGetHashParam(hash, HP_HASHSIZE, NULL, &hashLength, 0); printf("hashLength: %d\n", hashLength); And this prints out hashLength: 4 ! Can anyone explain what I am doing wrong or why Microsoft CAPI thinks that SHA1 is 4 bytes (32 bits) instead of 20 bytes (160 bits).

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  • structDelete doesn't affect the shallow copy?

    - by Travis
    I was playing around onError so I tried to create an error using a large xml document object. <cfset XMLByRef = variables.parsedXML.XMLRootElement.XMLChildElement> <cfset structDelete(variables.parsedXML, "XMLRootElement")> <cfset startXMLShortLoop = getTickCount()> <cfloop from = "1" to = "#arrayLen(variables.XMLByRef)#" index = "variables.i"> <cfoutput>#variables.XMLByRef[variables.i].id.xmltext#</cfoutput><br /> </cfloop> <cfset stopXMLShortLoop = getTickCount()> I expected to get an error because I deleted the structure I was referencing. From LiveDocs: Variable Assignment - Creates an additional reference, or alias, to the structure. Any change to the data using one variable name changes the structure that you access using the other variable name. This technique is useful when you want to add a local variable to another scope or otherwise change a variable's scope without deleting the variable from the original scope. instead I got 580df1de-3362-ca9b-b287-47795b6cdc17 25a00498-0f68-6f04-a981-56853c0844ed ... ... ... db49ed8a-0ba6-8644-124a-6d6ebda3aa52 57e57e28-e044-6119-afe2-aebffb549342 Looped 12805 times in 297 milliseconds <cfdump var = "#variables#"> Shows there's nothing in the structure, just parsedXML.xmlRoot.xmlName with the value of XMLRootElement. I also tried <cfset structDelete(variables.parsedXML.XMLRootElement, "XMLChildElement")> as well as structClear for both. More information on deleting from the xml document object. http://help.adobe.com/en_US/ColdFusion/9.0/Developing/WSc3ff6d0ea77859461172e0811cbec22c24-78e3.html Can someone please explain my faulty logic? Thanks.

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  • getting data from tableviewcell to 2nd view

    - by chubsta
    I am very new to this and am trying to learn by creating a few little apps for myself. I have a navigation-based app where the user taps the row to select a film title - i then want the second view to show details of the film. Thanks to a very helpful person here i am getting the results of the row pressed as 'rowTitle' as follows : (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { NSString *key = [keys objectAtIndex:indexPath.section]; NSArray *nameSection = [names objectForKey:key]; NSString *rowTitle = [nameSection objectAtIndex:indexPath.row]; NSLog(@"rowTitle = %@", rowTitle); [tableView deselectRowAtIndexPath:indexPath animated:YES]; I am, however, struggling to make the data at 'rowTitle' available to the 2nd view - basically, if i can get the info - for example rowTitle is "aliens2" - i want to be able to add a new extension to the end of the string returned by 'rowTitle' in order to point to an image (if that makes sense) in the second view... something like tempImageName=[** this is where the info from rowTitle needs to be i suppose**]; tempImageType=@".png"; finalImageName=[tempImageName stringByAppendingString:tempImageType]; does this make sense to anyone (apologies if it doesnt - i know what i want but how to explain it is a little more awkward!) Thanks again for any help anyone can give (and any help as to formatting these questions would be useful too obviously!!)!

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