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• Method of transforming 3D vectors with a matrix

  - by Drew Noakes

  I've been doing some reading on transforming Vector3 with matrices, and am tossing up digging deeper into the math and coding this myself versus using existing code. For whatever reason my school curriculum never included matrices, so I'm filling a gap in my knowledge. Thankfully I only need a few simple things, I think. Context is that I'm programming a robot for the RoboCup 3D league. I'm coding it in C# but it'll have to run on Mono. Ideally I wouldn't use any existing graphics libraries for this (WinForms/WPF/XNA) as all I really need is a neat subset of matrix transformations. Specifically, I need translation and x/y/z rotations, and a way of combining multiple transformations into a single matrix. This will then be applied to my own Vector3 type to produce the transformed Vector3. I've read different advice about this. For example, some model the transformation with a 4x3 matrix, others with a 4x4 matrix. Also, some examples show that you need a forth value for the vector's matrix of 1. What happens to this value when it's included in the output? [1 0 0 0] [x y z 1] * [0 1 0 0] = [a b c d] [0 0 1 0] [2 4 6 1] The parts I'm missing are: What sizes my matrices should be Compositing transformations by multiplying the transformation matrices together Transforming 3D vectors with the resulting matrix As I mostly just want to get this running, any psuedo-code would be great. Information about what matrix values perform what transformations is quite clearly defined on many pages, so need not be discussed here unless you're very keen :)

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• NSTask executed only once

  - by Eimantas

  I'm having trouble executing different NSTask's. Same launchPath, different arguments. I have a class who's instances administer own NSTask objects and depending on arguments those instances were initialized with - dependent NSTask object is being created. I have two initializers: // Method for finished task - (void)taskFinished:(NSNotification *)aNotification { [myTask release]; myTask = nil; [self createTask]; } // Designated initializer - (id) init { self = [super init]; if (self != nil) { [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(taskFinished:) name:NSTaskDidTerminateNotification object:nil]; [self createTask]; } return self; } // Convenience initializer - (id)initWithCommand:(NSString *)subCommand { self = [self init]; if (self) { [self setCommand:subCommand]; } return self; } And here 's the createTask method: - (void)createTask { // myTask is a property defined as NSTask* myTask = [[NSTask alloc] init]; [myTask setLaunchPath:@"/usr/bin/executable"]; } Say I have 3 buttons. Each one creates different class instance with different NSTask objects. But problem is that only first one gets executed. The second ones does not even triger "click" event (via target-action). I think it could be cause of launchPath I'm trying to use, 'cause simple /bin/ls works fine. The same command in terminal has 0 return value (i.e. all is fine). Any guides or gotchas are much appreciated.

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• clojure: ExceptionInInitializerError in Namespace.<init> loading from a non-default classpath

  - by Charles Duffy

  In attempting to load an AOT-compiled class from a non-default classpath, I receive the following exception: Traceback (innermost last): File "test.jy", line 10, in ? at clojure.lang.Namespace.<init>(Namespace.java:34) at clojure.lang.Namespace.findOrCreate(Namespace.java:176) at clojure.lang.Var.internPrivate(Var.java:149) at aot_demo.JavaClass.<clinit>(Unknown Source) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:247) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) java.lang.ExceptionInInitializerError: java.lang.ExceptionInInitializerError I'm able to reproduce this with the following trivial project.clj: (defproject aot-demo "0.1.0-SNAPSHOT" :dependencies [[org.clojure/clojure "1.3.0"]] :aot [aot-demo.core]) ...and src/aot_demo/core.clj defined as follows: (ns aot-demo.core (:gen-class :name aot_demo.JavaClass :methods [#^{:static true} [lower [java.lang.String] java.lang.String]])) (defn -lower [str] (.toLower str)) The following Jython script is then sufficient to trigger the bug: #!/usr/bin/jython import java.lang.Class import java.net.URLClassLoader import java.net.URL import os cl = java.net.URLClassLoader( [java.net.URL('file://%s/target/aot-demo-0.1.0-SNAPSHOT-standalone.jar' % (os.getcwd()))]) java.lang.Class.forName('aot_demo.JavaClass', True, cl) However, the exception does not occur if the test script is started with the uberjar already in the CLASSPATH variable. What's going on here? I'm trying to write a plugin for the BaseX database in Clojure; the above accurately represents how their plugin-loading mechanism works for the purpose of providing a SSCE for this problem.

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• what is the point of heterogenous arrays?

  - by aharon

  I know that more-dynamic-than-Java languages, like Python and Ruby, often allow you to place objects of mixed types in arrays, like so: ["hello", 120, ["world"]] What I don't understand is why you would ever use a feature like this. If I want to store heterogenous data in Java, I'll usually create an object for it. For example, say a User has int ID and String name. While I see that in Python/Ruby/PHP you could do something like this: [["John Smith", 000], ["Smith John", 001], ...] this seems a bit less safe/OO than creating a class User with attributes ID and name and then having your array: [<User: name="John Smith", id=000>, <User: name="Smith John", id=001>, ...] where those <User ...> things represent User objects. Is there reason to use the former over the latter in languages that support it? Or is there some bigger reason to use heterogenous arrays? N.B. I am not talking about arrays that include different objects that all implement the same interface or inherit from the same parent, e.g.: class Square extends Shape class Triangle extends Shape [new Square(), new Triangle()] because that is, to the programmer at least, still a homogenous array as you'll be doing the same thing with each shape (e.g., calling the draw() method), only the methods commonly defined between the two.

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• Inject App Settings using Windsor

  - by Damian Powell

  How can I inject the value of an appSettings entry (from app.config or web.config) into a service using the Windsor container? If I wanted to inject the value of a Windsor property into a service, I would do something like this: <properties> <importantIntegerProperty>666</importantIntegerProperty> </properties> <component id="myComponent" service="MyApp.IService, MyApp" type="MyApp.Service, MyApp" > <parameters> <importantInteger>#{importantIntegerProperty}</importantInteger> </parameters> </component> However, what I'd really like to do is take the value represented by #{importantIntegerProperty} from an app settings variable which might be defined like this: <appSettings> <add key="importantInteger" value="666"/> </appSettings> EDIT: To clarify; I realise that this is not natively possible with Windsor and the David Hayden article that sliderhouserules refers to is actually about his own (David Hayden's) IoC container, not Windsor. I'm surely not the first person to have this problem so what I'd like to know is how have other people solved this issue?

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• What is the performance penalty of XML data type in SQL Server when compared to NVARCHAR(MAX)?

  - by Piotr Owsiak

  I have a DB that is going to keep log entries. One of the columns in the log table contains serialized (to XML) objects and a guy on my team proposed to go with XML data type rather than NVARCHAR(MAX). This table will have logs kept "forever" (archiving some very old entries may be considered in the future). I'm a little worried about the CPU overhead, but I'm even more worried that DB can grow faster (FoxyBOA from the referenced question got 70% bigger DB when using XML). I have read this question http://stackoverflow.com/questions/514827/microsoft-sql-server-2005-2008-xml-vs-text-varchar-data-type and it gave me some ideas but I am particulairly interrested in clarification on whether the DB size increases or decreases. Can you please share your insight/experiences in that matter. BTW. I don't currently have any need to depend on XML features within SQL Server (there's nearly zero advantage to me in the specific case). Ocasionally log entries will be extracted, but I prefer to handle the XML using .NET (either by writing a small client or using a function defined in a .NET assembly).

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• How to create instances of related models in Django

  - by sevennineteen

  I'm working on a CMSy app for which I've implemented a set of models which allow for creation of custom Template instances, made up of a number of Fields and tied to a specific Customer. The end-goal is that one or more templates with a set of custom fields can be defined through the Admin interface and associated to a customer, so that customer can then create content objects in the format prescribed by the template. I seem to have gotten this hooked up such that I can create any number of Template objects, but I'm struggling with how to create instances - actual content objects - in those templates. For example, I can define a template "Basic Page" for customer "Acme" which has the fields "Title" and "Body", but I haven't figured out how to create Basic Page instances where these fields can be filled in. Here are my (somewhat elided) models... class Customer(models.Model): ... class Field(models.Model): ... class Template(models.Model): label = models.CharField(max_length=255) clients = models.ManyToManyField(Customer, blank=True) fields = models.ManyToManyField(Field, blank=True) class ContentObject(models.Model): label = models.CharField(max_length=255) template = models.ForeignKey(Template) author = models.ForeignKey(User) customer = models.ForeignKey(Customer) mod_date = models.DateTimeField('Modified Date', editable=False) def __unicode__(self): return '%s (%s)' % (self.label, self.template) def save(self): self.mod_date = datetime.datetime.now() super(ContentObject, self).save() Thanks in advance for any advice!

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• Java many to many association map

  - by Raphael Jolivet

  Hi, I have to classes, ClassA and ClassB and a "many to many" AssociationClass. I want to use a structure to hold the associations between A and B such as I can know, for each instance of A or B, which are their counterparts. I thought of using a Hashmap, with pair keys: Hasmap<Pair<ClassA, ClassB>, AssociationClass> associations; This way, I can add and remove an association between two instances of ClassA and ClassB, and I can query a relation for two given instances. However, I miss the feature of getting all associations defined for a given instance of ClassA or ClassB. I could do it by brute force and loop over all keys of the map to search for associations between a given instance, but this is inefficient and not elegant. Do you know of any data structure / free library that enables this ? I don't want to reinvent the wheel. Thanks in advance for your help, Raphael NB: This is not a "database" question. These objects are pure POJO used for live computation, I don't need persistence stuff.

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• Zipping with padding in Haskell

  - by Travis Brown

  A couple of times I've found myself wanting a zip in Haskell that adds padding to the shorter list instead of truncating the longer one. This is easy enough to write. (Monoid works for me here, but you could also just pass in the elements that you want to use for padding.) zipPad :: (Monoid a, Monoid b) => [a] -> [b] -> [(a, b)] zipPad xs [] = zip xs (repeat mempty) zipPad [] ys = zip (repeat mempty) ys zipPad (x:xs) (y:ys) = (x, y) : zipPad xs ys This approach gets ugly when trying to define zipPad3. I typed up the following and then realized that of course it doesn't work: zipPad3 :: (Monoid a, Monoid b, Monoid c) => [a] -> [b] -> [c] -> [(a, b, c)] zipPad3 xs [] [] = zip3 xs (repeat mempty) (repeat mempty) zipPad3 [] ys [] = zip3 (repeat mempty) ys (repeat mempty) zipPad3 [] [] zs = zip3 (repeat mempty) (repeat mempty) zs zipPad3 xs ys [] = zip3 xs ys (repeat mempty) zipPad3 xs [] zs = zip3 xs (repeat mempty) zs zipPad3 [] ys zs = zip3 (repeat mempty) ys zs zipPad3 (x:xs) (y:ys) (z:zs) = (x, y, z) : zipPad3 xs ys zs At this point I cheated and just used length to pick the longest list and pad the others. Am I overlooking a more elegant way to do this, or is something like zipPad3 already defined somewhere?

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• How to use IsKeyboardFocusWithin and IsSelected together?

  - by jpsstavares

  I have a style defined for my ListBoxItems with a trigger to set a background color when IsSelected is True: <Style x:Key="StepItemStyle" TargetType="{x:Type ListBoxItem}"> <Setter Property="SnapsToDevicePixels" Value="true"/> <Setter Property="OverridesDefaultStyle" Value="true"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="ListBoxItem"> <Border Name="Border" Padding="0" SnapsToDevicePixels="true"> <ContentPresenter /> </Border> <ControlTemplate.Triggers> <Trigger Property="IsSelected" Value="True"> <Setter TargetName="Border" Property="Background" Value="#40a0f5ff"/> </Trigger> </ControlTemplate.Triggers> </ControlTemplate> </Setter.Value> </Setter> </Style> This style maintains the selected item even when the ListBox and ListBoxItem loses focus, which in my case is an absolute must. The problem is that I also want the ListBoxItem to be selected when one of its TextBox's child gets focused. To achieve this I add a trigger that sets IsSelected to true when IsKeyboardFocusWithin is true: <Trigger Property="IsKeyboardFocusWithin" Value="True"> <Setter Property="IsSelected" Value="True" /> </Trigger> When I add this trigger the Item is selected when the focus is on a child TextBox, but the first behaviour disappears. Now when I click outside the ListBox, the item is de-selected. How can I keep both behaviours?

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• Execute function without sending 'self' to it

  - by Sergey

  Is that possible to define a function without referencing to self this way? def myfunc(var_a,var_b) But so that it could also get sender data, like if I defined it like this: def myfunc(self, var_a,var_b) That self is always the same so it looks a little redundant here always to run a function this way: myfunc(self,'data_a','data_b'). Then I would like to get its data in the function like this sender.fields. UPDATE: Here is some code to understand better what I mean. The class below is used to show a page based on Jinja2 templates engine for users to sign up. class SignupHandler(webapp.RequestHandler): def get(self, *args, **kwargs): utils.render_template(self, 'signup.html') And this code below is a render_template that I created as wrapper to Jinja2 functions to use it more conveniently in my project: def render_template(response, template_name, vars=dict(), is_string=False): template_dirs = [os.path.join(root(), 'templates')] logging.info(template_dirs[0]) env = Environment(loader=FileSystemLoader(template_dirs)) try: template = env.get_template(template_name) except TemplateNotFound: raise TemplateNotFound(template_name) content = template.render(vars) if is_string: return content else: response.response.out.write(content) As I use this function render_template very often in my project and usually the same way, just with different template files, I wondered if there was a way to get rid of having to call it like I do it now, with self as the first argument but still having access to that object.

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• How to test for existence of a script-scoped variable in PowerShell?

  - by Damian Powell

  Is it possible to test for the existence of a script-scoped variable in PowerShell? I've been using the PowerShell Community Extensions (PSCX) but I've noticed that if you import the module while Set-PSDebug -Strict is set, an error is produced: The variable '$SCRIPT:helpCache' cannot be retrieved because it has not been set. At C:\Users\...\Modules\Pscx\Modules\GetHelp\Pscx.GetHelp.psm1:5 char:24 While investigating how I might fix this, I found this piece of code in Pscx.GetHelp.psm1: #requires -version 2.0 param([string[]]$PreCacheList) if ((!$SCRIPT:helpCache) -or $RefreshCache) { $SCRIPT:helpCache = @{} } This is pretty straight forward code; if the cache doesn't exist or needs to be refreshed, create a new, empty cache. The problem is that calling $SCRIPT:helpCache while Set-PSDebug -Strict is in force casues the error because the variable hasn't been defined yet. Ideally, we could use a Test-Variable cmdlet but such a thing doesn't exist! I thought about looking in the variable: provider but I don't know how to determine the scope of a variable. So my question is: how can I test for the existence of a variable while Set-PSDebug -Strict is in force, without causing an error?

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• dynamic JSF composite component styling/rendering

  - by Checkoff

  I've a little problem with a composite component. This component's implementation looks like: <composite:implementation> <h:outputStylesheet name="foo.css" library="bar"/> <div id="#{cc.clientId}"> <composite:insertChildren/> </div> </composite:implementation> It is included dynamically into a facelet page which include this component with JSTL core tags. The facelet page is similar to the following one. <h:panelGroup id="viewport" layout="block"> <c:if test="#{controller.object != null}"> <c:forEach items="#{controller.object.elements}" var="element"> <c:if test="#{element.type == 'type1'}"> <my:componentTypeOne id="#{element.id}"/> </c:if> <c:if test="#{element.type == 'type2'}"> <my:componentTypeTwo id="#{element.id}"/> </c:if> </c:forEach> </c:if> </h:panelGroup> So when I only render the viewport of the page the components are rendered but without the stylesheet defined within the composite component my:component. Is there any way to include the stylesheet on the fly without rendering the whole page? EDIT: extension of the example code..

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• Does Perl auto-vivify variables used as references in subroutine calls?

  - by FM

  I've declared 2010 to be the year of higher-order programming, so I'm learning Haskell. The introduction has a slick quick-sort demo, and I thought, "Hey, that's easy to do in Perl". It turned to be easier than I expected. Note that I don't have to worry about whether my partitions ($less and $more) are defined. Normally you can't use an undefined value as an array reference. use strict; use warnings; use List::MoreUtils qw(part); my @data = (5,6,7,4,2,9,10,9,5,1); my @sorted = qsort(@data); print "@sorted\n"; sub qsort { return unless @_; my $pivot = shift @_; my ($less, $more) = part { $_ < $pivot ? 0 : 1 } @_; # Works, even though $less and $more are sometimes undefined. return qsort(@$less), $pivot, qsort(@$more); } As best I can tell, Perl will auto-vivify a variable that you try to use as a reference -- but only if you are passing it to a subroutine. For example, my call to foo() works, but not the attempted print. use Data::Dumper qw(Dumper); sub foo { print "Running foo(@_)\n" } my ($x); print Dumper($x); # Fatal: Can't use an undefined value as an ARRAY reference. # print @$x, "\n"; # But this works. foo(@$x); # Auto-vivification: $x is now []. print Dumper($x); My questions: Am I understanding this behavior correctly? What is the explanation or reasoning behind why Perl does this? Is this behavior explained anywhere in the docs?

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• C# parameters by reference and .net garbage collection

  - by Yarko

  I have been trying to figure out the intricacies of the .NET garbage collection system and I have a question related to C# reference parameters. If I understand correctly, variables defined in a method are stored on the stack and are not affected by garbage collection. So, in this example: public class Test { public Test() { } public int DoIt() { int t = 7; Increment(ref t); return t; } private int Increment(ref int p) { p++; } } the return value of DoIt() will be 8. Since the location of t is on the stack, then that memory cannot be garbage collected or compacted and the reference variable in Increment() will always point to the proper contents of t. However, suppose we have: public class Test { private int t = 7; public Test() { } public int DoIt() { Increment(ref t); return t; } private int Increment(ref int p) { p++; } } Now, t is stored on the heap as it is a value of a specific instance of my class. Isn't this possibly a problem if I pass this value as a reference parameter? If I pass t as a reference parameter, p will point to the current location of t. However, if the garbage collector moves this object during a compact, won't that mess up the reference to t in Increment()? Or does the garbage collector update even references created by passing reference parameters? Do I have to worry about this at all? The only mention of worrying about memory being compacted on MSDN (that I can find) is in relation to passing managed references to unmanaged code. Hopefully that's because I don't have to worry about any managed references in managed code. :)

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• Which to use, XMP or RDF?

  - by zotty

  What's the difference between RDF and XMP? From what I can tell, XMP is derived from RDF... so what does it offer that RDF doesn't? My particular situation is this: I've got some images which need tagging with details of how an experiment was performed, and what sort of data analysis has been performed on the images. A colleague of mine is pushing for XMP, but he's thinking of the images as photos - they're not really, they're just bits of data. From what I've seen (mainly by opening images in notepad++) the XMP data looks very similar to RDF - even so far as using RDF in the tag names (e.g. <rdf:Seq>). I'd like this data to be usable by other people who use similar instruments for similar experiments, so creating a mini standard (schema?) seems like the way to go. Apologies for the lack of fundemental understanding - I'm a Doctor, not a programmer! If it makes any difference, the language of choice will be C#. Edit for more information: First off, thanks for the excellent replies - thinking of XMP as a vocabulary for RDF makes things a lot clearer. The sort of data I'll be storing wont be avaliable in any of the pre-defined sets. It'll detail experimental set ups, locations and results. I think using RDF is the way to go.

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• Domain model: should things like Logging, Audit, Persistence be in it

  - by hom.tanks

  I'm having a hard time convincing our architect that a Domain model should only have the essential elements of the business domain on it. Things like the fact that a class is persistable, that it needs logging and auditing and that it has a RESTful URI should not drive the domain model. They can be added later on, by using interfaces. Ours is a healthcare information management system. At the very coarse level, its a system where users login and access their healthcare information. They can share this information with others and be custodian for others' information (think Roles). But because of a few sound bytes that caught on early like "Everything should be a REST resource" the model now has a top level class called Resource that every other class extends from. I'm trying to make him see that the domain model should have well defined concepts like User Account, HealthDocument, UserRole etc which are distinct entities of the business , with specific associations between them. Clubbing everything under Resource class lets our model be inflexible besides being potentially incorrect. But he wants me to show him why its a bad idea to do it his way. I don't know how to articulate that properly but all my OO instincts tell me that its just not right. Any thoughts?

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• ruby/datamapper: Refactor class methods to module

  - by DeSchleib

  Hello, i've the following code and tried the whole day to refactor the class methods to a sperate module to share the functionality with all of my model classes. Code (http://pastie.org/974847): class Merchant include DataMapper::Resource property :id, Serial [...] class << self @allowed_properties = [:id,:vendor_id, :identifier] alias_method :old_get, :get def get *args [...] end def first_or_create_or_update attr_hash [...] end end end I'd like to archive something like: class Merchant include DataMapper::Resource include MyClassFunctions [...] end module MyClassFunctions def get [...] def first_or_create_or_update[...] end => Merchant.allowed_properties = [:id] => Merchant.get( :id=> 1 ) But unfortunately, my ruby skills are to bad. I read a lot of stuff (e.g. here) and now i'm even more confused. I stumbled over the following two points: alias_method will fail, because it will dynamically defined in the DataMapper::Resource module. How to get a class method allowed_properties due including a module? What's the ruby way to go? Many thanks in advance.

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• What MS technology to use for HTTP service returning XML?

  - by Borek

  I need to create a service that: accepts HTTP requests (with query string or HTTP POST parameters) does some processing on the requests (checking if the request is valid, authentication etc.) reads data from a custom store (another HTTP call in our case) returns the result as custom XML (defined with XSD) I'm trying to think of various MS technologies that could help me and how good they would be for this scenario (pretty standard one I guess). The tasks above are relatively separate, this is what comes to mind: HTTP front-end: ASP.NET Web Forms ASP.NET MVC (seems more appropriate here as I won't need server controls, view state etc.) WCF? Don't know much about it or how well it would suit my task. Custom logic on the server: this will probably be a generic C# code in all cases (sometimes "plugged into" or called from MVC controllers or some equivalent place in other technologies) Reading data from internal data stores: As said, this is another HTTP server in our case. Options that come to mind: Just read the data using something like WebClient (Just theoretically) implement a LINQ provider (Just even more theoretically) implement an EF provider Output the data as custom XML: Linq2XML Serialization? Is it flexible enough? Does WCF provide some tools for this? Some "OXM" - Object/XML mapper if there is something like that for .NET I may be wrong in many of my assumptions, this is just a quick list that comes to mind after a quick research. Some general notes / questions: Testing is important Solution with a clear domain model would be much preferred over the one without Can Entity Framework actually help somewhere in my scenario? If so, where and how? Would WCF be an appropriate technology for this? I don't know much about it.

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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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• Delphi Client-Server Application using Firebird 2.5 embedded connection error

  - by Japster

  0 down vote favorite 1 share [fb] share [tw] I have got a lengthy question to ask. First of all Im still very new when it comes to Delphi programming and my experience has beem mostly developing small single user database applications using ADO and an Access database. I need to take the transition now to a client server application and this is where the problem starts. I decided to use Firebird 2.5 embeded as my database, as it is open source, and it is can be used with the interbase components in Delphi and that multiple clients can access the database simultanously. So I followed the interbase tutorial in Delphi. I managed to connect the client to the server and see the data in the example (While both are running on my pc), but when i tried to move the client to another pc, keeping the server on mine and running it to see if I can connect to the server it gave me the following error. Exception EIdSocketError in module clientDemo.exe at 0029DCAC. Socket Error # 10061 Connection refused. I understand that this might be because the host is defined as localhost in the client. But here is my first question. In the TSQLConncetion you can set die hostname under Driver-Hostname. The thing I want to know is how do you do this at run time, as I cannot get the property when I try and make an edit box to allow the user to enter the value and then set it via code like for example: SQLConncetion1.Driver.Hostname := edtHost.text; This cannot be done this way and the only way I see you can set the hostname is with the object inspector, but that is not available at runtime and I need to set the hostname on the client when the program is running the first time, so how do you set the hostname/IP address at runtime? Im using Delphi XE2 There is still a lot of questions to come especially when it comes to deployment, but I will take this piece by piece and I appreciate the advice.

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• Handle order dependence in loops

  - by Matt

  Hey all, I'm making a templating system where I instantiate each tag using a foreach loop. The issue is that some of the tags rely on each other so, I'm wondering how to get around that ordering from the looping. Here's an example: Class A { public $width; __construct() { $this->width = $B->width; // Undefined! Or atleast not set yet.. } } Class B { public $width; __construct() { $this->width = "500px"; } __tostring() { return "Hello World!"; } } Template.php $tags = array("A", "B"); foreach ($tags as $tag) { $TagObj[$tag] = new $tag(); } echo $TagObj['A']->width; // Nadamundo! EDIT: Ok just to clarify.. My main problem is that Class A relies on Class B, but class A is instantiated before class B, so therefore width has not yet been defined in class B. I am looking for a good way to make sure all the classes are loaded for everyone allowing the interdependencies to exist. For the future, please don't consider any syntax errors.. I just made up this example on the spot. Also assume that I have access to class B from class A after class B gets instantiated. I know this has applications elsewhere and I'm sure this has been solved before, if someone could enlighten me or point me in the right direction that'd be great! Thanks! Matt Mueler

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• How can I map stored procedure result into a custom class with linq-to-sql?

  - by Remnant

  I have a stored procedure that returns a result set (4 columns x n Rows). The data is based on multiple tables within my database and provides a summary for each department within a corporate. Here is sample: usp_GetDepartmentSummary DeptName EmployeeCount Male Female HR 12 5 7 etc... I am using linq-to-sql to retrieve data from my database (nb - have to use sproc as it is something I have inherited). I would like to call the above sproc and map into a department class: public class Department { public string DeptName {get; set;} public int EmployeeCount {get; set;} public int MaleCount {get; set;} public int FemaleCount {get; set;} } In VS2008, I can drag and drop my sproc onto the methods pane of the linq-to-sql designer. When I examine the designer.cs the return type for this sproc is defined as: ISingleResult<usp_GetDepartmentSummaryResult> What I would like to do is amend this somehow so that it returns a Department type so that I can pass the results of the sproc as a strongly typed view: <% foreach (var dept in Model) { %> <ul> <li class="deptname"><%= dept.DeptName %></li> <li class="deptname"><%= dept.EmployeeCount %></li> etc... Any ideas how to achieve this? NB - I have tried amending the designer.cs and dbml xml file directly but with limited success. I admit to being a little out of my depth when it comes to updating those files directly and I am not sure it is best practice? Would be good to get some diretion. Thanks much

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• C Run-Time library part 2

  - by b-gen-jack-o-neill

  Hi, I was suggested when I have some further questions on my older ones, to create newer Question and reffer to old one. So, this is the original question: What is the C runtime library? OK, from your answers, I now get thet statically linked libraries are Microsoft implementation of C standart functions. Now: If I get it right, the scheme would be as follow: I want to use printf(), so I must include which just tels compiler there us functio printf() with these parameters. Now, when I compile code, becouse printf() is defined in C Standart Library, and becouse Microsoft decided to name it C Run Time library, it gets automatically statically linked from libcmt.lib (if libcmt.lib is set in compiler) at compile time. I ask, becouse on wikipedia, in article about runtime library there is that runtime library is linked in runtime, but .lib files are linked at compile time, am I right? Now, what confuses me. There is .dll version of C standart library. But I thought that to link .dll file, you must actually call winapi program to load that library. So, how can be these functions dynamically linked, if there is no static library to provide code to tell Windows to load desired functions from dll? And really last question on this subject - are C Standart library functions also calls to winapi even they are not .dll files like more advanced WinAPI functions? I mean, in the end to access framebuffer and print something you must tell Windows to do it, since OS cannot let you directly manipulate HW. I think of it like the OS must be written to support all C standart library functions same way across similiar versions, since they are statically linked, and can differently support more complex WinAPI calls becouse new version of OS can have adjustements in the .dll file.

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• JSP: How can I still get the code on my error page to run, even if I can't display it?

  - by Josh Hinman

  I've defined an error-page in my web.xml: <error-page> <exception-type>java.lang.Exception</exception-type> <location>/error.jsp</location> </error-page> In that error page, I have a custom tag that I created. The tag handler for this tag e-mails me the stacktrace of whatever error occurred. For the most part this works great. Where it doesn't work great is if the output has already begun being sent to the client at the time the error occurs. In that case, we get this: SEVERE: Exception Processing ErrorPage[exceptionType=java.lang.Exception, location=/error.jsp] java.lang.IllegalStateException I believe this error happens because we can't redirect a request to the error page after output has already started. The work-around I've used is to increase the buffer size on particularly large JSP pages. But I'm trying to write a generic error handler that I can apply to existing applications, and I'm not sure it's feasible to go through hundreds of JSP pages making sure their buffers are big enough. Is there a way to still allow my stack trace e-mail code to execute in this case, even if I can't actually display the error page to the client?

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