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  • Python and Unicode: How everything should be Unicode

    - by A A
    Forgive if this a long a question: I have been programming in Python for around six months. Self taught, starting with the Python tutorial and then SO and then just using Google for stuff. Here is the sad part: No one told me all strings should be Unicode. No, I am not lying or making this up, but where does the tutorial mention it? And most examples also I see just make use of byte strings, instead of Unicode strings. I was just browsing and came across this question on SO, which says how every string in Python should be a Unicode string. This pretty much made me cry! I read that every string in Python 3.0 is Unicode by default, so my questions are for 2.x: Should I do a: print u'Some text' or just print 'Text' ? Everything should be Unicode, does this mean, like say I have a tuple: t = ('First', 'Second'), it should be t = (u'First', u'Second')? I read that I can do a from __future__ import unicode_literals and then every string will be a Unicode string, but should I do this inside a container also? When reading/ writing to a file, I should use the codecs module. Right? Or should I just use the standard way or reading/ writing and encode or decode where required? If I get the string from say raw_input(), should I convert that to Unicode also? What is the common approach to handling all of the above issues in 2.x? The from __future__ import unicode_literals statement? Sorry for being a such a noob, but this changes what I have been doing for a long time and so clearly I am confused.

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  • My 3D object (opengl es) is disappearing behind the iPhone camera view

    - by KLC
    I have an augmented reality iPhone app that I am converting from Core Animation to OpenGL ES 1.1. I have added code that has been modified from the Apple OpenGL template. My problem is that my 3D object , when translating along the negative Z-axis (away from the user), appears to disappear into the camera view, until its completely gone. I have experimented with several solutions, but to no avail. What I have determined: Using the 3D icosahedron from Jeff Lamarche's blog here, the object starts it at 0,0,0 and then translates with decreasing z coordinates. By the time the z value reaches -2.0f, the object is gone. It appears as if it is disappearing behind the camera view. This is how I set my frustrum & viewport (unchanged from Apple's code) glMatrixMode(GL_PROJECTION); size = zNear * tanf(DEGREES_TO_RADIANS(fieldOfView) / 2.0); //Grab the size of the screen CGRect rect = self.bounds; glFrustumf(-size, size, -size / (rect.size.width / rect.size.height), size / (rect.size.width / rect.size.height), zNear, zFar); glViewport(0, 0, rect.size.width, rect.size.height); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); What I have tried: The camera view is the main view and several other views are added to it as subviews, including the openGLView. I have commented those views out for test purposes. I have applied CATransforms to move the openGLView in the z direction -500 and +500, and done the same to the camera view. I have also changed the zFar in the above code to 1.0f, and it still disappears at z position of -2.0, which doesn't make sense (shouldn't it disappear at z=1.0?) My experimentation has got me more confused than when I started ( which usually means I am missing a key piece, but I can't figure out what). Thanks for your help.

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  • Easiest RPC client method in PHP

    - by T.K.
    I've been asked to help a friend's company to bring up a web application. I have very limited time and I reluctantly accepted the request, at one condition. As most of the logic goes on in the back-end, I suggested that I would finish the complete back-end only, allowing a front-end developer to simply interface with my backend. I plan to do the back-end in Java EE or Python (with Pylons). It does not really matter at this point. I plan to have my back-end completely ready and unit-tested, so that my input will hardly be needed after my work is done. I know they have a PHP programmer, but as far as I could tell he is a real rookie. I want him to basically interface with my backend's services in the easiest possible way, with no way of him "stuffing" it up. It's basically a CRUD-only application. I could implement the backend as accessible through a webservice such as XML-RPC or SOAP. Even a RESTful API could be possible. However, my main objective is to make something that complete "noob" PHP programmer can easily interface with without getting confused. Preferably I do not even want to talk to him because I generally have an extremely busy schedule, and doing "support calls" is not something I am willing to do. Which approach should I choose? I would welcome any suggestions and inputs!

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  • PHP: MVC and Model

    - by Pirkka
    Hello I`ve been wondering this one thing about creating models. If I make for example Page model. Is it the both: It can retrieve one row from the table or all the rows. Somehow Im mixing the objects and the database. I have thought it like this: I would have to make a Page-class that would represent one row in the table. It also would have all the basic CRUD-methods. Then I would have to do a Pages-class (somekind of collection) that would retrieve rows from the table and instantiate a Page object from each row. Is this kind of weird? If someone could explain to me the idea of model throughout.. Im again confused. Maybe Im thinking the whole OOP too difficult.. And by the way this forum is great. Hopefully people will just understand my problems. Heh. I was a long time procedural style programmer and now in 3 months I have dived into OOP and MVC and PHP frameworks and I just get more excited day by day when I explore this stuff!

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  • Why did instruments report a leak while its ref count did become zero

    - by bromj
    Hello guys, green hand i am. I'm using instruments, and it did a great help to me so far, but I'm confused now 'cause it report a memory leak to me while its leaked block history shows me that the ref count of that memory had finally become 0. What does it mean? It's really embarrassing that I couldn't post a image here... so I have to describe it in text. Hope it would be clear enough for you: Event Type || RefCt || Responsible Library || Responsible Caller Malloc         || 1        || MyWeather              || +[ForecastData parseSingleForecastWithXMLElement:] Autorelease||           || MyWeather              || +[ForecastData parseSingleForecastWithXMLElement:] Retain         || 2        || MyWeather              || +[ForecastData parseWithData:] Release      || 1        || Foundation              || +[NSAutoreleasePool drain:] Retain         || 2        || Foundation              || +[NSThread initWithTarget:selector:object:] Release      || 1        || Foundation              || +[NSString compare:options:] Release      || 0        || MyWeather              || +[RootViewController dealloc] Any help will be appreciated~

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  • Protected and Private methods

    - by cabaret
    I'm reading through Beginning Ruby and I'm stuck at the part about private and protected methods. This is a newbie question, I know. I searched through SO for a bit but I couldn't manage to find a clear and newbie-friendly explanation of the difference between private and protected methods. The book gives two examples, the first one for private methods: class Person def initialize(name) set_name(name) end def name @first_name + ' ' + @last_name end private def set_name(name) first_name, last_name = name.split(/\s+/) set_first_name(first_name) set_last_name(last_name) end def set_first_name(name) @first_name = name end def set_last_name(name) @last_name = name end end In this case, if I try p = Person.new("Fred Bloggs") p.set_last_name("Smith") It will tell me that I can't use the set_last_name method, because it's private. All good till there. However, in the other example, they define an age method as protected and when I do fred = Person.new(34) chris = Person.new(25) puts chris.age_difference_with(fred) puts chris.age It gives an error: :20: protected method 'age' called for #<Person:0x1e5f28 @age=25> (NoMethodError) I honestly fail to see the difference between the private and protected methods, it sounds the same to me. Could someone provide me with a clear explanation so I'll never get confused about this again? I'll provide the code for the second example if necessary.

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  • How to release a "PopUp" view"?

    - by david
    I have this class that shows a popup. I do a alloc-init on it and it comes up. DarkVader* darkPopUp = [[DarkVader alloc] init:theButton helpMessage:[theButton.titleLabel.text intValue] isADay:NO offset:0]; It shows itself and if the user presses Ok it disappears. When do I release this? I could do a [self release] in the class when the OK button is pressed. Is this correct? If I do this the Analyzer says it has a retain count of +1 and gets leaked in the calling function. If I release it just after the alloc-init the Analyzer says it has a retain count of +0 and i should not release it. DLog(@"DarkVader retain count: %i", [darkPopUp retainCount]); says it has a retain count of 2. I'm confused. In short my question is: How do I release an object that gets initialized does some work and ends but no one is there to release it in the calling function.

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  • Loading from archive?

    - by fuzzygoat
    Can anyone point me in the right direction, I have two sets of load/save methods below that I am playing with to save an array of objects out to disk and then load them back in. I am getting a little confused after calling "saveMoons" how I should go about loading that data back in ... any pointers would be great. -(void)saveMoons:(NSString *)savePath { NSMutableData *data = [[NSMutableData alloc] init]; NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data]; [moons encodeWithCoder:archiver]; [archiver finishEncoding]; [data writeToFile:savePath atomically:YES]; [data release]; [archiver release]; } -(void)loadMoons:(NSString *)loadPath { NSMutableData *data = [[NSMutableData alloc] initWithContentsOfFile:loadPath]; NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data]; // [self setMoons:[unarchiver ??????]]; } . // ------------------------------------------------------------------- ** // SIMPLER // ------------------------------------------------------------------- ** -(void)saveMoons_SIMPLE:(NSString *)savePath { NSData *data = [NSKeyedArchiver archivedDataWithRootObject:moons]; [data writeToFile:savePath atomically:YES]; } -(void)loadMoons_SIMPLE:(NSString *)loadPath { [self setMoons:[NSKeyedUnarchiver unarchiveObjectWithFile:loadPath]]; } // ------------------------------------------------------------------- ** // // ------------------------------------------------------------------- ** gary

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  • How to std::find using a Compare object?

    - by dehmann
    I am confused about the interface of std::find. Why doesn't it take a Compare object that tells it how to compare two objects? If I could pass a Compare object I could make the following code work, where I would like to compare by value, instead of just comparing the pointer values directly: typedef std::vector<std::string*> Vec; Vec vec; std::string* s1 = new std::string("foo"); std::string* s2 = new std::string("foo"); vec.push_back(s1); Vec::const_iterator found = std::find(vec.begin(), vec.end(), s2); // not found, obviously, because I can't tell it to compare by value delete s1; delete s2; Is the following the recommended way to do it? template<class T> struct MyEqualsByVal { const T& x_; MyEqualsByVal(const T& x) : x_(x) {} bool operator()(const T& y) const { return *x_ == *y; } }; // ... vec.push_back(s1); Vec::const_iterator found = std::find_if(vec.begin(), vec.end(), MyEqualsByVal<std::string*>(s2)); // OK, will find "foo"

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  • Is it safe to use random Unicode for complex delimiter sequences in strings?

    - by ccomet
    Question: In terms of program stability and ensuring that the system will actually operate, how safe is it to use chars like ¦, § or ‡ for complex delimiter sequences in strings? Can I reliable believe that I won't run into any issues in a program reading these incorrectly? I am working in a system, using C# code, in which I have to store a fairly complex set of information within a single string. The readability of this string is only necessary on the computer side, end-users should only ever see the information after it has been parsed by the appropriate methods. Because some of the data in these strings will be collections of variable size, I use different delimiters to identify what parts of the string correspond to a certain tier of organization. There are enough cases that the standard sets of ;, |, and similar ilk have been exhausted. I considered two-char delimiters, like ;# or ;|, but I felt that it would be very inefficient. There probably isn't that large of a performance difference in storing with one char versus two chars, but when I have the option of picking the smaller option, it just feels wrong to pick the larger one. So finally, I considered using the set of characters like the double dagger and section. They only take up one char, and they are definitely not going to show up in the actual text that I'll be storing, so they won't be confused for anything. But character encoding is finicky. While the visibility to the end user is meaningless (since they, in fact, won't see it), I became recently concerned about how the programs in the system will read it. The string is stored in one database, while a separate program is responsible for both encoding and decoding the string into different object types for the rest of the application to work with. And if something is expected to be written one way, is possibly written another, then maybe the whole system will fail and I can't really let that happen. So is it safe to use these kind of chars for background delimiters?

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  • constructor function's object literal returns toString() method but no other method

    - by JohnMerlino
    I'm very confused with javascript methods defined in objects and the "this" keyword. In the below example, the toString() method is invoked when Mammal object instantiated: function Mammal(name){ this.name=name; this.toString = function(){ return '[Mammal "'+this.name+'"]'; } } var someAnimal = new Mammal('Mr. Biggles'); alert('someAnimal is '+someAnimal); Despite the fact that the toString() method is not invoked on the object someAnimal like this: alert('someAnimal is '+someAnimal.toString()); It still returns 'someAnimal is [Mammal "Mr. Biggles"]' . That doesn't make sense to me because the toString() function is not being called anywhere. Then to add even more confusion, if I change the toString() method to a method I make up such as random(): function Mammal(name){ this.name=name; this.random = function(){ return Math.floor(Math.random() * 15); } } var someAnimal = new Mammal('Mr. Biggles'); alert(someAnimal); It completely ignores the random method (despite the fact that it is defined the same way was the toString() method was) and returns: [object object] Another issue I'm having trouble understanding with inheritance is the value of "this". For example, in the below example function person(w,h){ width.width = w; width.height = h; } function man(w,h,s) { person.call(this, w, h); this.sex = s; } "this" keyword is being send to the person object clearly. However, does "this" refer to the subclass (man) or the super class (person) when the person object receives it? Thanks for clearing up any of the confusion I have with inheritance and object literals in javascript.

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  • ASP .NET confusion - server controls

    - by Brandi
    I have read through the information in this question: http://stackoverflow.com/questions/22084/asp-net-aspxxx-controls-versus-standard-html but am still rather confused. The situation was I was asked to do a web project where I made a wizard. When I was done with the project everyone asked why I had used an <asp:Wizard...>. I thought this was what was being asked for, but apparently not, so after this I was led to believe that server controls were just prototyping tools. However, the next project I did my DB queries through C# code-behind and loaded the results via html. I was then asked why I had not used a gridview and a dataset. Does anyone have a list of pros and cons why they would choose to use specific html controls over specific server controls and why? I guess I'm looking for a list... what server controls are okay to use and why? EDIT: I guess this question is open ended, so I'll clarify a few more specific questions... Is it okay to use very simple controls such as asp:Label or do these just end up wasting space? It seems like it would be difficult to access html in the code behind otherwise. Are there a few controls that should just never be used? Does anyone have a good resource that will show me pros and cons of each control?

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  • Embed ActionScript (AS) into flash

    - by David ???
    Hey SO, I've never dealt with Flash/ActionScript, so please bear with me. Mostly, I'm a bit confused. I've done many work with Java/C as well as HTML/Javascript. I am working with a designer who provides me with flash files (.swf). From my point of view, it's a simple "mock" to which I need to embed a single object. This object is a TextBox, with which the user interacts. I need to be able to Insert such a TextBox to a Flash file Retrieve text upon key event process it, and return it to the TextBox As I understood from other posts, I'll be working with AS, right? How do I embed such an object to an existing Flash file? Being that the graphical part is over once I have the TextBox, would I need any fancy IDE for that? What IDE is that (I usually work with Eclipse)? One last note: I am working with that designer, so I have access to all her creation process. She does not know code, nor do I think she'll get it. I would much prefer to give her as little headache as possible (e.g. just instruct her how to export the files to me from her Adobe Flash CS5 studio). Many thanks, David

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  • Escaping colons in hibernate createSQLQuery

    - by Stratosgear
    I am confused on how I can create an SQL statement containing colons. I am trying to create a view and I am using (notice the double colons): create view MyView as ( SELECT tableA.colA as colA, tableB.colB as colB, round(tableB.colD / 1024)::numeric, 2) as calcValue, FROM tableA, tableB WHERE tableA.colC = 'someValue' ); This is a postgres query and I am forced to use the double colons (::) in order to correctly run the statement. I then pass the above statement through: s.createSQLQuery(myQuery).executeUpdate(); and I get a: Exception in thread "main" org.hibernate.exception.DataException: \ could not execute native bulk manipulation query at org.hibernate.exception.SQLStateConverter.convert(\ SQLStateConverter.java:102) ... more stacktrace... with an output of my above statement changed as (notice the question mark): create view MyView as ( SELECT tableA.colA as colA, tableB.colB as colB, round(tableB.colD / 1024)?, 2) as calcValue, FROM tableA, tableB WHERE tableA.colC = 'someValue' ); Obviously, hibernate confuses my colons with named parameters. Is there a way to escape the colons (a google suggestion that mentions that a single colon is escaped as a double colon does NOT work) or another way of running this statement? Thanks.

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  • Which apache worker to use with passenger and how?

    - by Millisami
    I've this config in my apache2.conf <IfModule mpm_prefork_module> StartServers 5 MinSpareServers 5 MaxSpareServers 10 MaxClients 150 MaxRequestsPerChild 0 </IfModule> # worker MPM # StartServers: initial number of server processes to start # MaxClients: maximum number of simultaneous client connections # MinSpareThreads: minimum number of worker threads which are kept spare # MaxSpareThreads: maximum number of worker threads which are kept spare # ThreadsPerChild: constant number of worker threads in each server process # MaxRequestsPerChild: maximum number of requests a server process serves <IfModule mpm_worker_module> StartServers 2 MaxClients 15 MinSpareThreads 4 MaxSpareThreads 5 ThreadsPerChild 15 MaxRequestsPerChild 50000 </IfModule> Now I'm confused here. Which module gets loaded on which conditions? The phusion guys have suggested to use the worker module. Since both are present in apache conf file, do I have to comment the mpm_prefork_module or leave it as it is? Following is my passenger conf file for apache: LoadModule passenger_module /usr/lib/ruby/gems/1.8/gems/passenger-2.2.4/ext/apache2/mod_passenger.so PassengerRoot /usr/lib/ruby/gems/1.8/gems/passenger-2.2.4 PassengerRuby /usr/bin/ruby1.8 PassengerMaxPoolSize 3 PassengerPoolIdleTime 999999 RailsFrameworkSpawnerIdleTime 0 RailsAppSpawnerIdleTime 0 I'm running just a single Rails 2.3.2 app on 256MB slice at slicehost. I'm not quite satisfied with the performance yet. Are the settings above are any good??

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  • jsf messed up links

    - by Mateusz
    I'm new to JSF. My application is working, but I'm confused with links in browser when using controller. BTW, there is also PrimeFaces in my app so don't be suprised with p: tags. Let's say I have 'list' and 'show' pages with controller doing redirection between them. First I'm on http://localhost:8080/y/r/conversation/list.xhtml page. There is link created with line <p:commandLink action="#{lazyConversationBean.doShow(conv)}" ajax="false" value="View"/>. lazyConversationBean acts here as my Controller. There is method: public String doShow(Conversation c) { this.setSelectedConversation(c); return "view"; } from which I got redirected to ...... again http://localhost:8080/y/r/conversation/list.xhtml (browser shows it) even when it's correct http://localhost:8080/y/r/conversation/view.xhtml page. There I have link <p:commandButton action="#{lazyConversationBean.doList()}" ajax="false" value="Back to list"/> and again controller has method: public String doList() { return "list"; } from which I got redirected to ... yeah, you guessed right ... http://localhost:8080/y/r/conversation/view.xhtml (that is again what browser shows) even when again it is correct http://localhost:8080/y/r/conversation/list.xhtml page. It seams as browser link area is always one step behind page currently being displayed. I don't even know if it's some incorrect behaviour as I have no idea how to query google for this :D Just for test I did this short tutorial, where netbeans created whole stack of code on one of my entities, and behaviour was the same, so it's not PrimeFaces magic related. Can you tell my why it happens, and how to fix it? Users likes to copy correct links ;)

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  • Why are symbols not frozen strings?

    - by Alex Chaffee
    I understand the theoretical difference between Strings and Symbols. I understand that Symbols are meant to represent a concept or a name or an identifier or a label or a key, and Strings are a bag of characters. I understand that Strings are mutable and transient, where Symbols are immutable and permanent. I even like how Symbols look different from Strings in my text editor. What bothers me is that practically speaking, Symbols are so similar to Strings that the fact that they're not implemented as Strings causes a lot of headaches. They don't even support duck-typing or implicit coercion, unlike the other famous "the same but different" couple, Float and Fixnum. The mere existence of HashWithIndifferentAccess, and its rampant use in Rails and other frameworks, demonstrates that there's a problem here, an itch that needs to be scratched. Can anyone tell me a practical reason why Symbols should not be frozen Strings? Other than "because that's how it's always been done" (historical) or "because symbols are not strings" (begging the question). Consider the following astonishing behavior: :apple == "apple" #=> false, should be true :apple.hash == "apple".hash #=> false, should be true {apples: 10}["apples"] #=> nil, should be 10 {"apples" => 10}[:apples] #=> nil, should be 10 :apple.object_id == "apple".object_id #=> false, but that's actually fine All it would take to make the next generation of Rubyists less confused is this: class Symbol < String def initialize *args super self.freeze end (and a lot of other library-level hacking, but still, not too complicated) See also: http://onestepback.org/index.cgi/Tech/Ruby/SymbolsAreNotImmutableStrings.red http://www.randomhacks.net/articles/2007/01/20/13-ways-of-looking-at-a-ruby-symbol Why does my code break when using a hash symbol, instead of a hash string? Why use symbols as hash keys in Ruby? What are symbols and how do we use them? Ruby Symbols vs Strings in Hashes Can't get the hang of symbols in Ruby

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  • OO vs Simplicity when it comes to user interaction

    - by Oetzi
    Firstly, sorry if this question is rather vague but it's something I'd really like an answer to. As a project over summer while I have some downtime from Uni I am going to build a monopoly game. This question is more about the general idea of the problem however, rather than the specific task I'm trying to carry out. I decided to build this with a bottom up approach, creating just movement around a forty space board and then moving on to interaction with spaces. I realised that I was quite unsure of the best way of proceeding with this and I am torn between two design ideas: Giving every space its own object, all sub-classes of a Space object so the interaction can be defined by the space object itself. I could do this by implementing different land() methods for each type of space. Only giving the Properties and Utilities (as each property has unique features) objects and creating methods for dealing with the buying/renting etc in the main class of the program (or Board as I'm calling it). Spaces like go and super tax could be implemented by a small set of conditionals checking to see if player is on a special space. Option 1 is obviously the OO (and I feel the correct) way of doing things but I'd like to only have to handle user interaction from the programs main class. In other words, I don't want the space objects to be interacting with the player. Why? Errr. A lot of the coding I've done thus far has had this simplicity but I'm not sure if this is a pipe dream or not for larger projects. Should I really be handling user interaction in an entirely separate class? As you can see I am quite confused about this situation. Is there some way round this? And, does anyone have any advice on practical OO design that could help in general?

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  • Emulating Visual Studio's Web Application "publish" at the command line

    - by cbp
    Hi, I am trying to automate my deployment process and am now thoroughly confused. I know that there are many questions on stackoverflow about this, but they all have different solutions and none of them work. I have a Web Application project which I usually publish by right-clicking and selecting "Publish". I get a dialog box where I use the following options: Build configuration: Release Publish method: File system Target location: C:\Deployments\MyWebsite Replace matching files with local copies I should mention that in the properties of the project I have "Items to deploy" set to "Only files needed to run this application". After running this, my entire solution is built, dependencies are resolved, build events are run, web.config transformations are applied and the website is copied to C:\Deployments\MyWebsite, although non-required files such as code-behind files are not copied. I have not been able to replicate this... in fact at this stage I'm not even sure which command line tool am I supposed to be using - msbuild, msdeploy or aspnet_compiler? This guy asks almost the same question but his solution doesn't work at all. For example, build events do not run correctly because the macros are not resolved. Whats more, the files do not get copied into the correct directory at all... I can't even begin to explain what happens!

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  • Beginning Haskell: "not in scope" Unprecedented error

    - by user1071838
    So I just started learning Haskell, and this (http://learnyouahaskell.com) nifty book is giving a lot of help. So yesterday I wrote in a text file doubleMe x = x + x and saved it as double.hs. So after saving that I open up my command prompt, CD to the right folder, type in "ghci" to get haskell started, and then type in >doubleMe 5 10 and everything seems to work. Now today, I do the same thing and this happens (actual copy paste from command line) . . . C:\Users\myName\haskell>ghci GHCi, version 7.0.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package ffi-1.0 ... linking ... done. Prelude> :l double.hs [1 of 1] Compiling Main ( double.hs, interpreted ) Ok, modules loaded: Main. *Main> doubleMe 5 <interactive>:1:1: Not in scope: `doubleMe' So basically, everything was working fine, but now haskell can't find the function I wrote in double.hs. Can anyone tell what is going on? I'm pretty lost and confused. This is just a guess but does it have to do with *Main at all? Thanks for the help.

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  • Type result with Ternary operator in C#

    - by Vaccano
    I am trying to use the ternary operator, but I am getting hung up on the type it thinks the result should be. Below is an example that I have contrived to show the issue I am having: class Program { public static void OutputDateTime(DateTime? datetime) { Console.WriteLine(datetime); } public static bool IsDateTimeHappy(DateTime datetime) { if (DateTime.Compare(datetime, DateTime.Parse("1/1")) == 0) return true; return false; } static void Main(string[] args) { DateTime myDateTime = DateTime.Now; OutputDateTime(IsDateTimeHappy(myDateTime) ? null : myDateTime); Console.ReadLine(); ^ } | } | // This line has the compile issue ---------------+ On the line indicated above, I get the following compile error: Type of conditional expression cannot be determined because there is no implicit conversion between '< null ' and 'System.DateTime' I am confused because the parameter is a nullable type (DateTime?). Why does it need to convert at all? If it is null then use that, if it is a date time then use that. I was under the impression that: condition ? first_expression : second_expression; was the same as: if (condition) first_expression; else second_expression; Clearly this is not the case. What is the reasoning behind this? (NOTE: I know that if I make "myDateTime" a nullable DateTime then it will work. But why does it need it? As I stated earlier this is a contrived example. In my real example "myDateTime" is a data mapped value that cannot be made nullable.)

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  • Is Form validation and Business validation too much?

    - by Robert Cabri
    I've got this question about form validation and business validation. I see a lot of frameworks that use some sort of form validation library. You submit some values and the library validates the values from the form. If not ok it will show some errors on you screen. If all goes to plan the values will be set into domain objects. Here the values will be or, better said, should validated (again). Most likely the same validation in the validation library. I know 2 PHP frameworks having this kind of construction Zend/Kohana. When I look at programming and some principles like Don't Repeat Yourself (DRY) and single responsibility principle (SRP) this isn't a good way. As you can see it validates twice. Why not create domain objects that do the actual validation. Example: Form with username and email form is submitted. Values of the username field and the email field will be populated in 2 different Domain objects: Username and Email class Username {} class Email {} These objects validate their data and if not valid throw an exception. Do you agree? What do you think about this aproach? Is there a better way to implement validations? I'm confused about a lot of frameworks/developers handling this stuff. Are they all wrong or am I missing a point? Edit: I know there should also be client side kind of validation. This is a different ballgame in my Opinion. If You have some comments on this and a way to deal with this kind of stuff, please provide.

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  • Using boost asio for pub/sub style tcp in a game loop

    - by unohoo
    I have been reading through the boost asio documentation for a couple of hours now, and while I think the documentation is really great, I am still left a bit confused on how to implement the system that I need. I have to stream info, from a game engine, to a list of computers over tcp. One snag is that, unlike traditional pub/sub, the computer that does the distribution of info is actually the computer that has to connect to the subscribers as well (instead of the subscribers registering with the publisher). This is done via a config file - a list of ip's/ports along with the data that they each require. The subscribers listen, but do not know the ip of the publisher. (As a side note, I'm quite new to network programming, so maybe I'm missing something .. but it's strange that I do not find much information regarding this style of "inverted" client-server model..) I am looking for suggestions for the implementation of such a system using boost asio. Of course I have to integrate the networking into an already existing engine, so with regards to that: What would be a good way to handle messages being sent to multiple computers every frame? Use async_write, call io_service.run and then reset every frame? Would having io_service.run have its own thread be better? Or should I just use threads and use blocking writes?

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  • Enums, Constructor overloads with similar conversions.

    - by David Thornley
    Why does VisualC++ (2008) get confused 'C2666: 2 overloads have similar conversions' when I specify an enum as the second parameter, but not when I define a bool type? Shouldn't type matching already rule out the second constructor because it is of a 'basic_string' type? #include <string> using namespace std; enum EMyEnum { mbOne, mbTwo }; class test { public: #if 1 // 0 = COMPILE_OK, 1 = COMPILE_FAIL test(basic_string<char> myString, EMyEnum myBool2) { } test(bool myBool, bool myBool2) { } #else test(basic_string<char> myString, bool myBool2) { } test(bool myBool, bool myBool2) { } #endif }; void testme() { test("test", mbOne); } I can work around this by specifying a reference 'ie. basic_string &myString' but not if it is 'const basic_string &myString'. Also calling explicitly via "test((basic_string)"test", mbOne);" also works. I suspect this has something to do with every expression/type being resolved to a bool via an inherent '!=0'. Curious for comments all the same :)

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  • What is the scope of TRANSACTION in Sql server

    - by Shantanu Gupta
    I was creating a stored procedure and i got stuck in the writing methodology of me and my collegue. I am using SQL Server 2005 I was writing Stored procedure like this BEGIN TRAN BEGIN TRY INSERT INTO Tags.tblTopic (Topic, TopicCode, Description) VALUES(@Topic, @TopicCode, @Description) INSERT INTO Tags.tblSubjectTopic (SubjectId, TopicId) VALUES(@SubjectId, @@IDENTITY) COMMIT TRAN END TRY BEGIN CATCH DECLARE @Error VARCHAR(1000) SET @Error= 'ERROR NO : '+ERROR_NUMBER() + ', LINE NO : '+ ERROR_LINE() + ', ERROR MESSAGE : '+ERROR_MESSAGE() PRINT @Error ROLLBACK TRAN END CATCH And my collegue was writing it like the below one BEGIN TRY BEGIN TRAN INSERT INTO Tags.tblTopic (Topic, TopicCode, Description) VALUES(@Topic, @TopicCode, @Description) INSERT INTO Tags.tblSubjectTopic (SubjectId, TopicId) VALUES(@SubjectId, @@IDENTITY) COMMIT TRAN END TRY BEGIN CATCH DECLARE @Error VARCHAR(1000) SET @Error= 'ERROR NO : '+ERROR_NUMBER() + ', LINE NO : '+ ERROR_LINE() + ', ERROR MESSAGE : '+ERROR_MESSAGE() PRINT @Error ROLLBACK TRAN END CATCH Here the only difference that you will find is the position of writing Begin TRAN. According to me the methodology of my collegue should not work when an exception occurs i.e. Rollback should not get executed because TRAN does'nt have scope. But when i tried to run both the code, both was working in the same way. I am confused to know how does TRANSACTION works. Is it scope free or what ?

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