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What's wrong with debugging in Eclipse on Android?

- by Sebastian Dwornik

I've obviously been spoiled by Visual Studio, because although I'm just learning Android and the Eclipse environment, debugging apps in Eclipse is becoming a serious detriment to further development. For example, Eclipse will compile this divide by zero just fine: public class Lesson2Main extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate (savedInstanceState); int i = 1 / 0; TextView tv = new TextView (this); tv.setText ("Hello, Android!"); setContentView (tv); } } And then, when it executes it under the debugger, I will get a full screen of useless debug info, non of which actually points me to the specific line containing the error. The stackTrace is null within the exception ('e') info tree, and it simply states a message stating 'ArithmeticException'. (that's nice, how about you point me in the direction of where you found it!?) I've looked all over the screen and am baffled that this IDE can't get this right. Does developing with Eclipse resort everyone back to 1991 with printf() like logging at every interval then to track down bugs? Seriously. Is there a configuration or plug-in that I'm missing to help with this? I haven't tested this case with XCode, but if the iPhone dev. IDE handles this more like Visual Studio, then no wonder the Android marketplace has so few apps. I'm excited about Android, but it seems that Eclipse is getting in the way.

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Properties vs. Fields: Need help grasping the uses of Properties over Fields.

- by pghtech

First off, I have read through a list of postings on this topic and I don't feel I have grasped properties because of what I had come to understand about encapsulation and field modifiers (private, public..ect). One of the main aspects of C# that I have come to learn is the importance of data protection within your code by the use of encapsulation. I 'thought' I understood that to be because of the ability of the use of the modifiers (private, public, internal, protected). However, after learning about properties I am sort of torn in understanding not only properties uses, but the overall importance/ability of data protection (what I understood as encapsulation) within C#. To be more specific, everything I have read when I got to properties in C# is that you should try to use them in place of fields when you can because of: 1) they allow you to change the data type when you can't when directly accessing the field directly. 2) they add a level of protection to data access However, from what I 'thought' I had come to know about the use of field modifiers did #2, it seemed to me that properties just generated additional code unless you had some reason to change the type (#1) - because you are (more or less) creating hidden methods to access fields as opposed to directly. Then there is the whole modifiers being able to be added to Properties which further complicates my understanding for the need of properties to access data. I have read a number of chapters from different writers on "properties" and none have really explained a good understanding of properties vs. fields vs. encapsulation (and good programming methods). Can someone explain: 1) why I would want to use properties instead of fields (especially when it appears I am just adding additional code 2) any tips on recognizing the use of properties and not seeing them as simply methods (with the exception of the get;set being apparent) when tracing other peoples code? 3) Any general rules of thumb when it comes to good programming methods in relation to when to use what? Thanks and sorry for the long post - I didn't want to just ask a question that has been asked 100x without explaining why I am asking it again.

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Uncaught exception while using xdebug

- by rich97

I'm not too great with xdebug so forgive me if this is a stupid question. But I installed it on a separate machine and it performed some magic for me like formating my var_dump() output and catching any uncaught exceptions. It also fails to format the stack traces, outputting plain text which is extremely hard to read. As I am learning the Lithium PHP Framework I am required to use php5.3, on my other machine I compiled from the source but on this machine I'm using the precompiled packages from dotdeb.org. As far as I can tell the only difference is that this is a slightly newer version of php and it comes with the Suhosin patch. The other odd thing is that the xdebug functions such as xdebug_var_dump() work, aside from poor formatting. This is an Ubuntu machine, so I don't know if it could be anything to do with the dotdep packages, but I have installed xdebug through pecl, the downloadable tarball and from the SVN repository. But to no avail. You can see my php.ini and output of php -i in the following gist. I copied php.ini from /etc/php5/apache2/php.ini over to /etc/php5/cli/php.ini so php -i should reflect my apache setup. http://gist.github.com/391675 Any help is appreciated. Rich

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Anything speaking against the bitnami.org Ruby/Rails/Redmine Stack?

- by Pekka

I am looking to set up a Redmine server on a Windows virtual machine on my local workstation. (Background in this related question.) I have zero knowledge of Ruby nor Rails, and while Redmine may be the opportunity to dip into those platforms somewhat, my first goal is to get it running as quickly and easily as possible. For that, I am eyeing the Bitnami Redmine Package. It promises point-and-click install, and a self-contained environment with everything you need. Apart from the learning factor, are there any serious limitations this method implies? Any serious cutdowns in customizability? I will be wanting to customize the template right away, for example, and install plugins. The package looks o.k. to me but before I install it, I was curious to know whether anybody would advise against it and why. Edit: The first impression is great. From 0 to a working Redmine installation in twelve minutes! Wow.

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Getting Started with Ruby & Ruby on Rails

- by JakeTheSnake

Some background: I'm a jack-of-all traits, one of which is programming. I learned VB6 through Excel and PHP for creating websites and so far it's worked out just fine for me. I'm not CS major or even mathematically inclined - logic is what interests me. Current status: I'm willing to learn new and more powerful languages; my first foray into such a route is learning Ruby. I went to the main Ruby website and did the interactive intro. (by the way, I'm currently getting redirected to google.com when I try the link...it's happening to other websites as well...is my computer infected?) I liked what I learned and wanted to get started using Ruby to create websites. I downloaded InstantRails and installed it; everything so far has been fine - the program starts up just fine, and I can test some Ruby code in the console. However my troubles begin when I try and view a web page with Ruby code present. Lastly, my problem: As in PHP, I can browse to the .php file directly and through using PHP tags and some simple 'echo' statements I can be on my way in making dynamic web pages. However with the InstantRails app working, accessing a .rb or .rhtml page doesn't produce similar results. I made a simple text file named 'test.rb' and put basic HTML tags in there (html, head, body) and the Ruby tags <%= and % with some ruby code inside. The web page actually shows the tags and the code - as if it's all just plain HTML. I take it Ruby isn't parsing the page before it is displayed to the user, but this is where my lack of understanding of the Ruby environment stops me short. Where do I go from here?

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Class Plugins in PHP?

- by YuriKolovsky

i just got some more questions while learning PHP, does php implement any built in plugin system? so the plugin would be able to change the behavior of the core component. for example something like this works: include 'core.class.php'; include 'plugin1.class.php'; include 'plugin2.class.php'; new plugin2; where core.class.php contains class core { public function coremethod1(){ echo 'coremethod1'; } public function coremethod2(){ echo 'coremethod2'; } } plugin1.class.php contains class plugin1 extends core { public function coremethod1(){ echo 'plugin1method1'; } } plugin2.class.php contains class plugin2 extends plugin1 { public function coremethod2(){ echo 'plugin2method2'; } } This would be ideal, if not for the problem that now the plugins are dependable on each other, and removing one of the plugins: include 'core.class.php'; //include 'plugin1.class.php'; include 'plugin2.class.php'; new plugin2; breaks the whole thing... are there any proper methods to doing this? if there are not, them i might consider moving to a different langauge that supports this... thanks for any help.

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Recognize Dates In A String

- by Tim Scott

I want a class something like this: public interface IDateRecognizer { DateTime[] Recognize(string s); } The dates might exist anywhere in the string and might be any format. For now, I could limit to U.S. culture formats. The dates would not be delimited in any way. They might have arbitrary amounts of whitespace between parts of the date. The ideas I have are: ANTLR Regex Hand rolled I have never used ANTLR, so I would be learning from scratch. I wonder if there are libraries or code samples out there that do something similar that could jump start me. Is ANTLR too heavy for such a narrow use? I have used Regex a lot before, but I hate it for all the reasons that most people hate it. I could certainly hand roll it but I'd rather not re-solve a solved problem. Suggestions? UPDATE: Here is an example. Given this input: This is a date 11/3/63. Here is another one: November 03, 1963; and another one Nov 03, 63 and some more (11/03/1963). The dates could be in any U.S. format. They might have dashes like 11-2-1963 or weird extra whitespace inside like this: Nov 3, 1963, and even maybe the comma is missing like [Nov 3 63] but that's an edge case. The output should be an array of seven DateTimes. Each date would be the same: 11/03/1963 00:00:00.

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Beyond core java

- by Paul

Coming to the end of the first year of my CS degree, we've done some Java but just the core stuff; manipulating strings and arrays, inheritance, implementing logic etc. I visit this website daily and I see so much stuff that is beyond me; using frameworks; managing databases etc. It makes me feel like I've just learned the syntax of Java, and there is so much more to do with it. My question is though, how do I get there? I don't think I'm advanced enough to join an open source project, which seems to be suggested often (though I'd love to) and I've looked at other similar questions on here (like this one) but even then I don't think that'd work for me.. firstly, could somebody try give me some commonly used frameworks etc and how and what they are used for? Where would be a good place to start? How did you get started in using the things you do? Or perhaps you think I'm going down the wrong route. Should I learn another language, and just wait until the moment occurs where it's clear what I should be doing? I'm only in the first year of my degree, so far we've lightly covered Haskell and Java, and I've done a little HTML and CSS in my free time. I know that next year we cover python, so perhaps I should just wait till then and see if I prefer that? I feel like I also risk learning something in depth and then never using it... I suppose I'm also asking for personal experiences; was there a point where you felt you'd exceeded the basic grasp of a language (does not necessarily have to be Java related) and reach a more "advanced" level? I guess I'll put subjective tag on this, but really I just want to know how to get beyond the basic understanding of a language.

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How do I apply a "template" or "skeleton" of code in C# here?

- by Scott Stafford

In my business layer, I need many, many methods that follow the pattern: public BusinessClass PropertyName { get { if (this.m_LocallyCachedValue == null) { if (this.Record == null) { this.m_LocallyCachedValue = new BusinessClass( this.Database, this.PropertyId); } else { this.m_LocallyCachedValue = new BusinessClass( this.Database, this.Record.ForeignKeyName); } } return this.m_LocallyCachedValue; } } I am still learning C#, and I'm trying to figure out the best way to write this pattern once and add methods to each business layer class that follow this pattern with the proper types and variable names substituted. BusinessClass is a typename that must be substituted, and PropertyName, PropertyId, ForeignKeyName, and m_LocallyCachedValue are all variables that should be substituted for. Are attributes usable here? Do I need reflection? How do I write the skeleton I provided in one place and then just write a line or two containing the substitution parameters and get the pattern to propagate itself? EDIT: Modified my misleading title -- I am hoping to find a solution that doesn't involve code generation or copy/paste techniques, and rather to be able to write the skeleton of the code once in a base class in some form and have it be "instantiated" into lots of subclasses as the accessor for various properties. EDIT: Here is my solution, as suggested but left unimplemented by the chosen answerer. // I'll write many of these... public BusinessClass PropertyName { get { return GetSingleRelation(ref this.m_LocallyCachedValue, this.PropertyId, "ForeignKeyName"); } } // That all call this. public TBusinessClass GetSingleRelation<TBusinessClass>( ref TBusinessClass cachedField, int fieldId, string contextFieldName) { if (cachedField == null) { if (this.Record == null) { ConstructorInfo ci = typeof(TBusinessClass).GetConstructor( new Type[] { this.Database.GetType(), typeof(int) }); cachedField = (TBusinessClass)ci.Invoke( new object[] { this.Database, fieldId }); } else { var obj = this.Record.GetType().GetProperty(objName).GetValue( this.Record, null); ConstructorInfo ci = typeof(TBusinessClass).GetConstructor( new Type[] { this.Database.GetType(), obj.GetType()}); cachedField = (TBusinessClass)ci.Invoke( new object[] { this.Database, obj }); } } return cachedField; }

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How do I define a Calculated Measure in MDX based on a Dimension Attribute?

- by ShaneD

I would like to create a calculated measure that sums up only a specific subset of records in my fact table based on a dimension attribute. Given: Dimension Date LedgerLineItem {Charge, Payment, Write-Off, Copay, Credit} Measures LedgerAmount Relationships * LedgerLineItem is a degenerate dimension of FactLedger If I break down LedgerAmount by LedgerLineItem.Type I can easily see how much is charged, paid, credit, etc, but when I do not break it down by LedgerLineItem.Type I cannot easily add the credit, paid, credit, etc into a pivot table. I would like to create separate calculated measures that sum only specific type (or multiple types) of ledger facts. An example of the desired output would be: | Year | Charged | Total Paid | Amount - Ledger | | 2008 | $1000 | $600 | -$400 | | 2009 | $2000 | $1500 | -$500 | | Total | $3000 | $2100 | -$900 | I have tried to create the calculated measure a couple of ways and each one works in some circumstances but not in others. Now before anyone says do this in ETL, I have already done it in ETL and it works just fine. What I am trying to do as part of learning to understand MDX better is to figure out how to duplicate what I have done in the ETL in MDX as so far I am unable to do that. Here are two attempts I have made and the problems with them. This works only when ledger type is in the pivot table. It returns the correct amount of the ledger entries (although in this case it is identical to [amount - ledger] but when I try to remove type and just get the sum of all ledger entries it returns unknown. CASE WHEN ([Ledger].[Type].currentMember = [Ledger].[Type].&[Credit]) OR ([Ledger].[Type].currentMember = [Ledger].[Type].&[Paid]) OR ([Ledger].[Type].currentMember = [Ledger].[Type].&[Held Money: Copay]) THEN [Measures].[Amount - ledger] ELSE 0 END This works only when ledger type is not in the pivot table. It always returns the total payment amount, which is incorrect when I am slicing by type as I would only expect to see the credit portion under credit, the paid portion, under paid, $0 under charge, etc. sum({([Ledger].[Type].&[Credit]), ([Ledger].[Type].&[Paid]), ([Ledger].[Type].&[Held Money: Copay])}, [Measures].[Amount - ledger]) Is there any way to make this return the correct numbers regardless of whether Ledger.Type is included in my pivot table or not?

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Help me understand dynamic layouts in Sinatra

- by thermans

Help me understand this; I'm learning Sinatra (and Rails for that matter, er, and Ruby). Say I'm doing a search app. The search form is laid out in one div, and the results will be laid out in another. The search form is rendered into the div by a previous view (maybe from a login form). I want to process the form params, perform the search, and render the results into the results div. If I have a single "yield" in the layout and render the divs from different views, the results div erases the search div when it renders. If I define the divs in the default layout, then just render the content, obviously the layout will be messed up: there would have to be two "yields" and I don't think Sinatra supports passing blocks in to yields. I tried foca's sinatra-content-for plugin, and that seems closer to what I need. But I can't figure out where to place the "yield_content" statements. If I have this haml in my layout: #search -# search form = yield_content :search #results -# search results = yield_content :results ... this in my search view: - content_for :search do %form{:method => "post"... etc. ... and this in the results view: - content_for :results do %table{:class => 'results'... etc. This sort of works but when I render the results view, the search div is emptied out. I would like to have it remain. Am I doing something wrong? How should I set this up?

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Should frontend and backend handled by different controllers?

- by DR

In my previous learning projects I always used a single controller, but know I wonder if that is good practice or even always possible. In all RESTful Rails tutorials the controllers have a show, an edit and an index view. If an authorized user is logged on, the edit view becomes available and the index view shows additional data manipulation controls, like a delete button or a link to the edit view. Now I have a Rails application which falls exactly into this pattern, but the index view is not reusable: The normal user sees a flashy index page with lots of pictures, complex layout, no Javascript requirement, ... The Admin user index has a completly different minimalistic design, jQuery table and lots of additional data, ... Now I'm not sure how to handle this case. I can think of the following: Single controller, single view: The view is split into two large blocks/partials using an if statement. Single controller, two views: index and index_admin. Two different controllers: BookController and BookAdminController None of this solutions seems perfect, but for now I'm inclined to use the 3rd option. What's the preferred way to do this?

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Is there a way to prevent Maven Test from rebuilding the database?

- by Christopher W. Allen-Poole

I've recently been asked to, effectively, sell my department on unit testing. I can't tell you how excited this makes me, but I do have one concern. We're using JUnit with Spring and Maven, and this means that each time mvn test is called, it rebuilds the database. Obviously, we can't integrate that with our production server -- it would kill valuable data. How do I prevent the rebuilding without telling maven to skip testing? The best I could figure was to assign the script to operate in a test database (line breaks added for readability): mvn test -Ddbunit.schema=<database>test -Djdbc.url=jdbc:mysql://localhost/<database>test? createDatabaseIfNotExist=true& useUnicode=true&characterEncoding=utf-8 I can't help but think there must be a better way. I'm especially interested in learning if there is an easy way to tell Maven to only run tests on particular classes without building anything else? mvn -Dtest=<test-name> test still rebuilds the database. ======= update ======= Bit of egg on my face here. I didn't realize that I was using the same variable in two places, meaning that the POM was using a "skip.test" variable for both rebuilding the database and for running the tests...

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Boost::thread mutex issue: Try to lock, access violation

- by user1419305

I am currently learning how to multithread with c++, and for that im using boost::thread. I'm using it for a simple gameengine, running three threads. Two of the threads are reading and writing to the same variables, which are stored inside something i call PrimitiveObjects, basicly balls, plates, boxes etc. But i cant really get it to work, i think the problem is that the two threads are trying to access the same memorylocation at the same time, i have tried to avoid this using mutex locks, but for now im having no luck, this works some times, but if i spam it, i end up with this exception: First-chance exception at 0x00cbfef9 in TTTTT.exe: 0xC0000005: Access violation reading location 0xdddddded. Unhandled exception at 0x77d315de in TTTTT.exe: 0xC0000005: Access violation reading location 0xdddddded. These are the functions inside the object that im using for this, and the debugger is also blaming them for the exception. void PrimitiveObj::setPos(glm::vec3 in){ boost::mutex mDisposingMutex; boost::try_mutex::scoped_try_lock lock(mDisposingMutex); if ( lock) { position = in; boost::try_mutex::scoped_try_lock unlock(mDisposingMutex); } } glm::vec3 PrimitiveObj::getPos(){ boost::mutex myMutex; boost::try_mutex::scoped_try_lock lock(myMutex); if ( lock) { glm::vec3 curPos = position; boost::try_mutex::scoped_try_lock unlock(myMutex); return curPos; } return glm::vec3(0,0,0); } Any ideas?

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Order in many to many relation in Django model

- by Pietro Speroni

I am writing a small website to store the papers I have written. The relation papers<- author is important, but the order of the name of the authors (which one is First Author, which one is second order, and so on) is also important. I am just learning Django so I don't know much. In any case so far I have done: from django.db import models class author(models.Model): Name = models.CharField(max_length=60) URLField = models.URLField(verify_exists=True, null=True, blank=True) def __unicode__(self): return self.Name class topic(models.Model): TopicName = models.CharField(max_length=60) def __unicode__(self): return self.TopicName class publication(models.Model): Title = models.CharField(max_length=100) Authors = models.ManyToManyField(author, null=True, blank=True) Content = models.TextField() Notes = models.TextField(blank=True) Abstract = models.TextField(blank=True) pub_date = models.DateField('date published') TimeInsertion = models.DateTimeField(auto_now=True) URLField = models.URLField(verify_exists=True,null=True, blank=True) Topic = models.ManyToManyField(topic, null=True, blank=True) def __unicode__(self): return self.Title This work fine in the sense that I now can define who the authors are. But I cannot order them. How should I do that? Of course I could add a series of relations: first author, second author,... but it would be ugly, and would not be flexible. Any better idea? Thanks

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Eclipse and JavaFX? is it just me?

- by jeff porter

I'm looking at learning JavaFX. I've tried setting Eclipse to develop a small app and I've downloaded the Eclipse plugin. Eclipse JavaFX plugin BUT... it just seems, well, flakey. So I have 3 questions... 1: Is there a better plugin? 2: Or is there some great set of tutorials out there that I'm missing? 3: finally, is it meant to be easy to call Java code from FX? I'm stuggling, it there a good example somewhere? On questions 1 & 2, Eclipse underlines code in red that just shouln't be. For example.. see this image... Why does it underline bit of imports in red? I know this is little of an open ended question. So I guess my main question is this... Is my experiance of JavaFX and Eclipse the best I can hope for? Or am I missing something ? (and I'm not looking for a Yes/No response) :-) Just looking for a discussion on how best to learn/develop JavaFx.

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Why does Jcreator show iIlegal start of expression?

- by Inusual Whisper Sinclair

I am new at programming and currently in our classes we are learning java. I am trying to create a routine in which I need to use String variables only. Below it is the code in which I am working with: public static void main(String[] args) throws java.io.IOException { BufferedReader in = new BufferedReader(new InputStreamReader(System. in )); PrintStream out = System.out; String hair.equals("damagedHair"); cutHair(marvin); cleanHair(michelle); for (int i = 0; i < 2; i++) { static void cutHair(String marvin) { String cabello; marvin.equals(hair); if (marvin.equals("damagedHair")) { cabello.equals("newHaircut"); result(hair); } static void cleanHair(String michelle) { String hair; michelle.equals(hair); if (michelle.equals(newHaircut)) { hair.equals("putShampooAndConditioner"); result(hair); } static void result(String pHair) {; PrintStream out = System.out; out.println("============="); out.println(pHair); out.println("============="); } } Jcreator is giving me an error that says Illegal start of expression and also java 50 error ';' expected. I am not sure why is this coming up and I am a little confused as to whether I am doing something I am not supposed to and how to correct it. Sorry about the double posting, this is the right message. Need some help from you guys to figure this out. Thanks in advanced!

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Hibernate query for multiple items in a collection

- by aarestad

I have a data model that looks something like this: public class Item { private List<ItemAttribute> attributes; // other stuff } public class ItemAttribute { private String name; private String value; } (this obviously simplifies away a lot of the extraneous stuff) What I want to do is create a query to ask for all Items with one OR MORE particular attributes, ideally joined with arbitrary ANDs and ORs. Right now I'm keeping it simple and just trying to implement the AND case. In pseudo-SQL (or pseudo-HQL if you would), it would be something like: select all items where attributes contains(ItemAttribute(name="foo1", value="bar1")) AND attributes contains(ItemAttribute(name="foo2", value="bar2")) The examples in the Hibernate docs didn't seem to address this particular use case, but it seems like a fairly common one. The disjunction case would also be useful, especially so I could specify a list of possible values, i.e. where attributes contains(ItemAttribute(name="foo", value="bar1")) OR attributes contains(ItemAttribute(name="foo", value="bar2")) -- etc. Here's an example that works OK for a single attribute: return getSession().createCriteria(Item.class) .createAlias("itemAttributes", "ia") .add(Restrictions.conjunction() .add(Restrictions.eq("ia.name", "foo")) .add(Restrictions.eq("ia.attributeValue", "bar"))) .list(); Learning how to do this would go a long ways towards expanding my understanding of Hibernate's potential. :)

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Any high-level languages that can use c libraries?

- by Isaiah

I know this question could be in vain, but it's just out of curiosity, and I'm still much a newb^^ Anyways I've been loving python for some time while learning it. My problem is obviously speed issues. I'd like to get into indie game creation, and for the short future, 2d and pygame will work. But I'd eventually like to branch into the 3d area, and python is really too slow to make anything 3d and professional. So I'm wondering if there has ever been work to create a high-level language able to import and use c libraries? I've looked at Genie and it seems to be able to use certain libraries, but I'm not sure to what extent. Will I be able to use it for openGL programing, or in a c game engine? I do know some lisp and enjoy it a lot, but there aren't a great many libraries out there for it. Which leads to the problem: I can't stand C syntax, but C has libraries galore that I could need! And game engines like irrlicht. Is there any language that can be used in place of C around C? Thanks so much guys

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Why is there a constructor method if you can assign the values to variables?

- by Joel

I'm just learning PHP, and I'm confused about what the purpose of the __construct() method? If I can do this: class Bear { // define properties public $name = 'Bill'; public $weight = 200; // define methods public function eat($units) { echo $this->name." is eating ".$units." units of food... <br />"; $this->weight += $units; } } Then why do it with a constructor instead? : class Bear { // define properties public $name; public $weight; public function __construct(){ $this->name = 'Bill'; $this->weight = 200; } // define methods public function eat($units) { echo $this->name." is eating ".$units." units of food... <br />"; $this->weight += $units; } }

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Trying to get a better understanding of SelectedValuePath and IsSynchronizedWithCurrentItem

- by rasx

The following XAML produces a run-time Binding error when I click on an item in the ListBox: <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:sys="clr-namespace:System;assembly=mscorlib" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Class="WpfApplication1.MainWindow" x:Name="Window" Title="MainWindow" Width="640" Height="480"> <Window.Resources> <x:Array x:Key="strings" Type="{x:Type sys:String}"> <sys:String>one</sys:String> <sys:String>two</sys:String> <sys:String>three</sys:String> <sys:String>four</sys:String> </x:Array> </Window.Resources> <Grid> <ListBox DataContext="{StaticResource strings}" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding}" SelectedValuePath="{Binding /Length}"> <ListBox.ItemTemplate> <DataTemplate> <Grid> <Grid.Resources> <Style TargetType="{x:Type Label}"> <Setter Property="Background" Value="Yellow"/> <Setter Property="Margin" Value="0,0,4,0"/> <Setter Property="Padding" Value="0"/> </Style> </Grid.Resources> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition/> </Grid.ColumnDefinitions> <Grid.RowDefinitions> <RowDefinition/> <RowDefinition/> </Grid.RowDefinitions>  <Label Grid.Column="0" Grid.Row="0">String:</Label> <TextBlock Grid.Column="1" Grid.Row="0" Text="{Binding}"/>  <Label Grid.Column="0" Grid.Row="1">Length:</Label> <TextBlock Grid.Column="1" Grid.Row="1" Text="{Binding Length, Mode=Default}"/> </Grid> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </Grid> </Window> This is the run-time Binding error message: System.Windows.Data Error: 39 : BindingExpression path error: '3' property not found on 'object' ''String' (HashCode=1191344027)'. BindingExpression:Path=3; DataItem='String' (HashCode=1191344027); target element is 'ListBox' (Name=''); target property is 'NoTarget' (type 'Object') I would like the selected value of the ListBox to be the Length of the selected String object. What is wrong with my SelectedValuePath Binding syntax? Are there any related issues with IsSynchronizedWithCurrentItem?

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What does O(log n) mean exactly?

- by Andreas Grech

I am currently learning about Big O Notation running times and amortized times. I understand the notion of O(n) linear time, meaning that the size of the input affects the growth of the algorithm proportionally...and the same goes for, for example, quadratic time O(n2) etc..even algorithms, such as permutation generators, with O(n!) times, that grow by factorials. For example, the following function is O(n) because the algorithm grows in proportion to its input n: f(int n) { int i; for (i = 0; i < n; ++i) printf("%d", i); } Similarly, if there was a nested loop, the time would be O(n2). But what exactly is O(log n)? For example, what does it mean to say that the height of a complete binary tree is O(log n)? I do know (maybe not in great detail) what Logarithm is, in the sense that: log10 100 = 2, but I cannot understand how to identify a function with a logarithmic time.

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can I disable the "(Type e to repeat macro)" message in emacs?

- by lindes

Hi there, So, I've finally made the plunge, and have gotten to the state where I'm quite happy to have switched from vi and vim to emacs... I've been putting stuff in my .emacs file, learning how to evaluate things (not to mention becoming familiar with movement commands), etc. etc. etc. And now I have a problem with a require line in my .emacs file (a require statement*), which bombs out when I launch emacs (and generally fails to work). So, this lead me to the following situation: In the process of trying to debug the above situation, one of the steps I did was to open the file I was trying to require, and evaluate it bit by bit, using C-M-f and C-x C-e (and later just M-x eval-buffer), which all worked fine. But along the way of the section-by-section, I got tired of typing all those, and so I recorded a keyboard macro... C-x ( C-M-f C-x C-e C-x ) and then C-x e... which gave me a message in the minibuffer (I think I'm using the right name), saying (Type e to repeat macro). Which meant I could no longer see the resultant value of the evaluation of each section of code... which, while not critical in this case, I was liking having. Which leads me to the actual question: Is there a way to disable that message, and/or to cause the minibuffer to show multiple lines at once? I know about the *Messages* buffer, and that could have helped, I'm just wondering if there's a way to either disable that message, or otherwise make it coexist with other messages. Any suggestions? Thanks! lindes * - the problem at hand, which is not really my question, is that (require 'ruby-mode/ruby-mode) fails, even though emacs is definitely and successfully (per system call tracing) opening and reading the ruby-mode.el file. I presume this is because the provide line says just 'ruby-mode. I've found a solution for this, but if anyone can point me to any "best practices", I'd appreciate it.

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Select * from 'many to many' SQL relationship

- by Rampant Creative Group

I'm still learning SQL and my brain is having a hard time with this one. Say I have 3 tables: teams players and teams_players as my link table All I want to do is run a query to get each team and the players on them. I tried this: SELECT * FROM teams INNER JOIN teams_players ON teams.id = teams_players.team_id INNER JOIN players ON teams_players.player_id = players.id But it returned a separate row for each player on each team. Is JOIN the right way to do it or should I be doing something else? ----------------------------------------- Edit Ok, so from what I'm hearing, this isn't necessarily a bad way to do it. I'll just have to group the data by team while I'm doing my loop. I have not yet tried the modified SQL statements provided, but I will today and get back to you. To answer the question about structure - I guess I wasn't thinking about the returned row structure which is part of what lead to my confusion. In this particular case, each team is limited to 4 players (or less) so I guess the structure that would be helpful to me is something like the following: teams.id, teams.name, players.id, players.name, players.id, players.name, players.id, players.name, players.id, players.name, 1 Team ABC 1 Jim 2 Bob 3 Ned 4 Roy 2 Team XYZ 2 Bob 3 Ned 5 Ralph 6 Tom

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What ORM for .NET should I use?

- by eKek0

I'm relatively new to .NET and have being using Linq2Sql for a almost a year, but it lacks some of the features I'm looking for now. I'm going to start a new project in which I want to use an ORM with the following characteristics: It has to be very productive, I don't want to be dealing with the access layer to save or retrieve objects from or to the database, but it should allows me to easily tweak any object before actually commit it to the database; also it should allows me to work easily with a changing database schema It should allows me to extend the objects mapped from the database, for example to add virtual attributes to them (virtual columns to a table) It has to be (at least almost) database agnostic, it should allows me to work with different databases in a transparent way It has to have not so much configuration or must be based on conventions to make it work It should allows me to work with Linq So, do you know any ORM that I could use? Thank you for your help. EDIT I know that an option is to use NHibernate. This appears as the facto standard for enterprise level applications, but also it seems that is not very productive because its deep learning curve. In other way, I have read in some other post here in SO that it doesn't integrate well with Linq. Is all of that true?

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