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• My first Lisp macro; is it leaky?

  - by Tom Martin

  I've been working through Practical Common Lisp and as an exercise decided to write a macro to determine if a number is a multiple of another number: (defmacro multp (value factor) `(= (rem ,value ,factor) 0)) so that : (multp 40 10) evaluates to true whilst (multp 40 13) does not The question is does this macro leak in some way? Also is this "good" Lisp? Is there already an existing function/macro that I could have used?

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• Using typedefs (or #defines) on built in types - any sensible reason?

  - by jb

  Well I'm doing some Java - C integration, and throught C library werid type mappings are used (theres more of them;)): #define CHAR char /* 8 bit signed int */ #define SHORT short /* 16 bit signed int */ #define INT int /* "natural" length signed int */ #define LONG long /* 32 bit signed int */ typedef unsigned char BYTE; /* 8 bit unsigned int */ typedef unsigned char UCHAR; /* 8 bit unsigned int */ typedef unsigned short USHORT; /* 16 bit unsigned int */ typedef unsigned int UINT; /* "natural" length unsigned int*/ Is there any legitimate reason not to use them? It's not like char is going to be redefined anytime soon. I can think of: Writing platform/compiler portable code (size of type is underspecified in C/C++) Saving space and time on embedded systems - if you loop over array shorter than 255 on 8bit microprocessor writing: for(uint8_t ii = 0; ii < len; ii++) will give meaureable speedup.

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• Correct structure and way of website versioning

  - by Saif Bechan

  Recently I use GIT to version my website. It makes it all really easy to see how my project develops and I always have save backups on different places on the web. Now my main question is if it is recommended to version your whole root of the website. I have a basic structure that looks something like this: /httpdocs /config /media /application index.php .htaccess 1) Should I use the /httpdocs folder to version, or should I use the content of the folder. 2) Is it recommended to version the media folder. In the media version I have several images for the overall layout, and some other images for the website. These imagas can be quite large. I work on these images from time to time and so they change. I hardly never need the old image again, so is this not just taking up precious storage space. I would highly appreciate just some basic recommendation on this topic.

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• How to expose a constructor variable(sic!) as read-only?

  - by Malax

  Hi StackOverflow! I have this rather simple question about Scala. Given that i have to following class definition: class Foo(var bar: Int) The code which is able to construct an instance of Foo must be able to pass the initial value for bar. But if I define bar as var the User is also able to change its value at runtime which is not what I want. The User should only be able to read bar. bar itself is modified internally so a val is not an option. I think I might be getting an answer very soon as this question is so simple. :-) Cheers, Malax

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• Why are there magic attributes exposed in the Servlet spec?

  - by Brabster

  It's always seemed a little at odds with the principles of Java that the Java Servlet Spec (2.5 version here) includes a set of magic attributes containing info about included resources, namely: javax.servlet.include.request_uri javax.servlet.include.context_path javax.servlet.include.servlet_path javax.servlet.include.path_info javax.servlet.include.query_string It's not even specifically pointed out in the API documentation, only in the spec where it is a must for correct implementation. This approach feels very wrong, an exposed implementation detail that clients will use and depend on. Why is this information exposed in this way?

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• Me As Child Type In General Function

  - by Steven

  I have a MustInherit Parent class with two Child classes which Inherit from the Parent. How can I use (or Cast) Me in a Parent function as the the child type of that instance? EDIT: My actual goal is to be able to serialize (BinaryFormatter.Serialize(Stream, Object)) either of my child classes. However, "repeating the code" in each child "seems" wrong. EDIT2: This is my Serialize function. Where should I implement this function? Copying and pasting to each child doesn't seem right, but casting the parent to a child doesn't seem right either. Public Function Serialize() As Byte() Dim bFmt As New BinaryFormatter() Dim mStr As New MemoryStream() bFmt.Serialize(mStr, Me) Return mStr.ToArray() End Function

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• Learning Javascript in one weekend?

  - by dueyfinster

  Similiar to this question, I am wondering if experienced Javascript developers have any websites they use with examples to get the basics of Javascript down in 24/28 hours? I have looked at Douglas Crockford's Google Tech Talk and I bought the book "Javascript: the good parts" but I haven't had time to read it.

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• Should checkins be small steps or complete features?

  - by Caspin

  Two of version controls uses seem to dictate different checkin styles. distibution centric: changesets will generally reflect a complete feature. In general these checkins will be larger. This style is more user/maintainer friendly. rollback centric: changesets will be individual small steps so the history can function like an incredibly powerful undo. In general these checkins will be smaller. This style is more developer friendly. I like to use my version control as really powerful undo while while I banging away at some stubborn code/bug. In this way I'm not afraid to make drastic changes just to try out a possible solution. However, this seems to give me a fragmented file history with lots of "well that didn't work" checkins. If instead I try to have my changeset reflect complete features I loose the use of my version control software for experimentation. However, it is much easier for user/maintainers to figure out how the code is evolving. Which has great advantages for code reviews, managing multiple branches, etc. So what's a developer to do? checkin small steps or complete features?

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• WPF binding to a boolean on a control

  - by Jose

  I'm wondering if someone has a simple succinct solution to binding to a dependency property that needs to be the converse of the property. Here's an example I have a textbox that is disabled based on a property in the datacontext e.g.: <TextBox IsEnabled={Binding CanEdit} Text={Binding MyText}/> The requirement changes and I want to make it ReadOnly instead of disabled, so without changing my ViewModel I could do this: In the UserControl resources: <UserControl.Resources> <m:NotConverter x:Key="NotConverter"/> </UserControl.Resources> And then change the TextBox to: <TextBox IsReadOnly={Binding CanEdit,Converter={StaticResource NotConverter}} Text={Binding MyText}/> Which I personally think is EXTREMELY verbose I would love to be able to just do this(notice the !): <TextBox IsReadOnly={Binding !CanEdit} Text={Binding MyText}/> But alas, that is not an option that I know of. I can think of two options. Create an attached property IsNotReadOnly to FrameworkElement(?) and bind to that property If I change my ViewModel then I could add a property CanEdit and another CannotEdit which I would be kind of embarrassed of because I believe it adds an irrelevant property to a class, which I don't think is a good practice. The main reason for the question is that in my project the above isn't just for one control, so trying to keep my project as DRY as possible and readable I am throwing this out to anyone feeling my pain and has come up with a solution :)

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• Multiple-File Template Implementation

  - by Maxpm

  With normal functions, the declaration and definition are often separated across multiple files like so: // Foo.h namespace Foo { void Bar(); } . // Foo.cpp #include "Foo.h" void Foo::Bar() { cout << "Inside function." << endl; } It is my understanding that this cannot be done with templates. The declaration and definition must not be separate because the appropriate form of the template is created "on-demand" when needed. So, how and where are templates typically defined in a multiple-file project like this? My intuition is that it would be in Foo.cpp because that's where the "meat" of functions normally is, but on the other hand it's the header file that's going to be included.

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• Is it okay if my ViewModel 'creates' bindable user controls for my View?

  - by j0rd4n

  I have an entry-point View with a tab control. Each tab is going to have a user control embedded within it. Each embedded view inherits from the same base class and will need to be updated as a key field on the entry-point view is updated. I'm thinking the easiest way to design this page is to have the entry-point ViewModel create and expose a collection of the tabbed views so the entry-point View can just bind to the user control elements using a DataTemplate on the tab control. Is it okay for a ViewModel to instantiate and provide UI elements for its View?

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• Proper way to name booleans that are A or B not True False

  - by Hurricanepkt

  I have a field that indicates whether someone wars a commission or a fee. In sql its going to be a bit field. How should I name it?

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• How to refactor this Ruby on Rails code?

  - by yuval

  I want to fetch posts based on their status, so I have this code inside my PostsController index action. It seems to be cluttering the index action, though, and I'm not sure it belongs here. How could I make it more concise and where would I move it in my application so it doesn't clutter up my index action (if that is the correct thing to do)? if params[:status].empty? status = 'active' else status = ['active', 'deleted', 'commented'].include?(params[:status]) ? params[:status] : 'active' end case status when 'active' #active posts are not marked as deleted and have no comments is_deleted = false comments_count_sign = "=" when 'deleted' #deleted posts are marked as deleted and have no comments is_deleted = true comments_count_sign = "=" when 'commented' #commented posts are not marked as deleted and do have comments is_deleted = false comments_count_sign = ">" end @posts = Post.find(:all, :conditions => ["is_deleted = ? and comments_count_sign #{comments_count_sign} 0", is_deleted])

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• Is this 2D array initialization a bad idea?

  - by Brendan Long

  I have something I need a 2D array for, but for better cache performance, I'd rather have it actually be a normal array. Here's the idea I had but I don't know if it's a terrible idea: const int XWIDTH = 10, YWIDTH = 10; int main(){ int * tempInts = new int[XWIDTH * YWIDTH]; int ** ints = new int*[XWIDTH]; for(int i=0; i<XWIDTH; i++){ ints[i] = &tempInts[i*YWIDTH]; } // do things with ints delete[] ints[0]; delete[] ints; return 0; } So the idea is that instead of newing a bunch of arrays (and having them placed in different places in memory), I just point to an array I made all at once. The reason for the delete[] (int*) ints; is because I'm actually doing this in a class and it would save [trivial amounts of] memory to not save the original pointer. Just wondering if there's any reasons this is a horrible idea. Or if there's an easier/better way. The goal is to be able to access the array as ints[x][y] rather than ints[x*YWIDTH+y].

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• Stateless singleton VS Static methods

  - by Sebastien Lorber

  Hey, Don't find any good answer to this simple question about helper/utils classes: Why would i create a singleton (stateless) rather than static methods? Why an object instance could be needed while the object has no state? Sometimes i really don't know what to use...

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• Ideal way to set global uncaught exception Handler in Android

  - by Samuh

  I want to set a global uncaught exception handler for all the threads in my Android application. So, in my Application subclass I set an implementation of Thread.UncaughtExceptionHandler as default handler for uncaught exceptions. Thread.setDefaultUncaughtExceptionHandler( new DefaultExceptionHandler(this)); In my implementation, I am trying to display an AlertDialog displaying appropriate exception message. However, this doesn't seem to work. Whenever, an exception is thrown for any thread which goes un-handled, I get the stock, OS-default dialog (Sorry!-Application-has-stopped-unexpectedly dialog). What is the correct and ideal way to set a default handler for uncaught exceptions? Thanks.

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• What Security Issues I should have in PHP Hosting

  - by phpBOY

  Hi, Just wanted to know what could be the security cautions I should know about PHP Hosting? Thanks

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• Recommendations with hierarchical data on non-relational databases?

  - by Luki

  I'm developing an web application that uses a non-relational database as a backend (django-nonrel + AppEngine). I need to store some hierarchical data (projects/subproject_1/subproject_N/tasks), and I'm wondering which pattern should I use. For now I thought of: Adjacency List (store the item's parent id) Nested sets (store left and right values for the item) In my case, the depth of nesting for a normal user will not exceed 4-5 levels. Also, on the UI, I would like to have a pagination for the items on the first level, to avoid to load too many items at the first page load. From what I understand so far, nested sets are great when the hierarchy is used more for displaying. Adjacency lists are great when editing on the tree is done often. In my case I guess I need the displaying more than the editing (when using nested sets, even if the display would work great, the above pagination could complicate things on editing). Do you have any thoughts and advice, based on your experience with the non-relational databases?

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• Is it OK to write code after [super dealloc]? (Objective-C)

  - by Richard J. Ross III

  I have a situation in my code, where I cannot clean up my classes objects without first calling [super dealloc]. It is something like this: // Baseclass.m @implmentation Baseclass ... -(void) dealloc { [self _removeAllData]; [aVariableThatBelongsToMe release]; [anotherVariableThatBelongsToMe release]; [super dealloc]; } ... @end This works great. My problem is, when I went to subclass this huge and nasty class (over 2000 lines of gross code), I ran into a problem: when I released my objects before calling [super dealloc] I had zombies running through the code that were activated when I called the [self _removeAllData] method. // Subclass.m @implementation Subclass ... -(void) deallloc { [super dealloc]; [someObjectUsedInTheRemoveAllDataMethod release]; } ... @end This works great, and It didn't require me to refactor any code. My question Is this: Is it safe for me to do this, or should I refactor my code? Or maybe autorelease the objects? I am programming for iPhone if that matters any.

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• Approaching Java from a Ruby perspective

  - by Travis

  There are plenty of resources available to a Java developer for getting a jump-start into Ruby/Rails development. The reverse doesn't appear to be true. What resources would you suggest for getting up-to-date on the current state of java technologies? How about learning how to approach DRY (don't repeat yourself) without the use of metaprogramming? Or how to approach various scenarios where a ruby developer is used to passing in a function (proc/lambda/block) as an argument (callbacks, etc)?

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• What does the expression "Fail Early" mean, and when would you want to do so?

  - by Andrew Grimm

  What does the expression "Fail Early" mean, and under what circumstances is this approach most useful, and when would you avoid the approach?

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• In which controller do you put the CRUD for the child part of a relationship?

  - by uriDium

  I am using ASP.Net MVC but this probably applies to all MVC patterns in general. My problem, for example I have companies and in each company I have a list of contacts. When I have selected a company I can see its details and a list of the contacts for that company. When I want to add a new contact for that company, should the implementation of that action go into the company controller as an "AddContact" action or should it go into the contact controller into a "New" action and we pass the Company ID in the URL? What is the usual way of dealing with this sort of thing in ASP.Net MVC? Is there a better stategy?

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• To trigger everytime with .click()?

  - by Dejan.S

  I tried to have a .click() on a <a> to find out it wont trigger every time I click, what it suppose to do is open a dialog. That is not the only problem I would need to pass a value to my jquery to. I just cant figure this one out. I need it to be a <a> because it's gone be in a dropdown menu. Do you got any suggestions? this is the code I use so far $(document).ready(function() { $('a').click(function() { var first = "<iframe style='width: 100%; height: 100%;' src='" + need to put value here + "'</iframe>'"; $('.iframe').html(first); $('#dialog').dialog({ bgiframe: true, modal: true, height: 600, width: 1000 }); }); }); thanks guys

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• Database Structure for CakePHP Models

  - by Michael T. Smith

  We're building a data tracking web app using CakePHP, and I'm having some issues getting the database structure right. We have Companies that haveMany Sites. Sites haveMany DataSamples. Tags haveAndBelongToMany Sites. That is all set up fine. The problem is "ranking" the sites within tags. We need to store it in the database as an archive. I created a Rank model that is setup like this: rank ( id (int), sample_id (int), tag_id (int), site_id (int), rank (int), total_rows) ) So, the question is, how do I create the associations for tag, site and sample to rank? I originally set them as haveMany. But the returned structures don't get me where I'd like to be. It looks like: [Site] => Array ( [Sample] = Array(), [Tag] = Array() ) When I'm really looking for: [Site] => Array ( [Tag] = Array ( [Sample] => Array ( [Rank] => Array ( ...data... ) ) ) ) I think that I may not be structuring the database properly; so if I need to update please let me know. Otherwise, how do I write a find query that gets me where I need to be? Thanks! Thoughts? Need more details? Just ask!

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• Should a C++ constructor do real work?

  - by Wade Williams

  I'm strugging with some advice I have in the back of my mind but for which I can't remember the reasoning. I seem to remember at some point reading some advice (can't remember the source) that C++ constructors should not do real work. Rather, they should initialize variables only. The advice when on to explain that real work should be done in some sort of init() method, to be called separately after the instance was created. The situation is I have a class that represents a hardware device. It makes logical sense to me for the constructor to call the routines that query the device in order to build up the instance variables that describe the device. In other words, once new instantiates the object, the developer receives an object which is ready to be used, no separate call to object-init() required. Is there a good reason why constructors shouldn't do real work? Obviously it could slow allocation time, but that wouldn't be any different if calling a separate method immediately after allocation. Just trying to figure out what gotchas I not currently considering that might have lead to such advice.

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