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  • Java CRTP: Works for container but not for methods?

    - by Daniel
    I have a baseclass with a protected static ArrayList. I want to have a seperate ArrayList for each kind of subclass that extends this baseclass. This is when I applied CRTP: public class BaseExample<T> { protected static ArrayList<Integer> data = new ArrayList<Integer>(); } This works just fine. However, when I try to implement the following static method in the same base class, it doesn't adhere to CRTP: public static void clear() { data.clear(); } For example: class SubExample extends BaseExample<SubExample> { // insertion methods accessing 'data' field // these work fine :) } SubExample.clear(); // does not seem to clear data container Do I need to somehow explicitly specify T in my baseclass clear method? Note: These are all pure static classes.

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  • What is Ruby's double-colon (::) all about?

    - by Meltemi
    I'd probably be able to answer this for myself if "::" wasn't so hard to Google. Didn't see anything on SO so thought I'd try my luck. What is this double-colon :: all about? I see it everywhere in Rails: class User < ActiveRecord::Base or… ActionController::Routing::Routes.draw do |map| I found a definition from this guy: The :: is a unary operator that allows: constants, instance methods and class methods defined within a class or module, to be accessed from anywhere outside the class or module. but that just leads to more questions. What good is scope (private, protected) if you can just use :: to expose anything?

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  • Paperclip - Validate File Type but not Presence

    - by Lowgain
    I am using paperclip to handle my file uploads, and in one situation I don't want the file to be mandatory. I do however want to make sure it is a specific file type when it is present. I have this: class TestModel < ActiveRecord::Base #stuff has_attached_file :sound #etc... validates_attachment_content_type :sound, :content_type => ['audio/mp3', 'application/x-mp3'] end And when I have no sound file present, it tells me it is not one of the valid content types. I've tried adding '' to the :content_type array, which also doesn't work! I also attempted creating a lambda procedure for the :if property, but I can't get it to run without some kind of error. Anything missing here?

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  • getJSON for dropbox data

    - by gheil.apl
    Although i used getJSON in http://jsbin.com/dbJSON/edit i have not been able to connect with any of my own made up data. i tried 4, and the example at Flickr for "cats". Only the latter worked... this is the output: {assoc: null,assoc.js: null,stub: null,stub.js: null,cat: [object Object]} i am at that "base", as i did get the image there, but db.tgu.ca/repsychal/poems/10/0512-g2g/assoc.json db.tgu.ca/repsychal/poems/10/0512-g2g/assoc.js db.tgu.ca/repsychal/poems/10/0512-g2g/stub.json db.tgu.ca/repsychal/poems/10/0512-g2g/stub.js were all invisible==null! (they are all URL, just put h t t p //: in front ... a restriction on the # of URL in a post) How do i get "my" data into the page?

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  • habtm multiple times with the same model

    - by Ermin
    I am trying to model a publications. A publication can have multiple authors and editors. Since it is possible that one person is an author of one publication and an editor of another, no separate models for Authors and Editors: class Publication < ActiveRecord::Base has_and_belongs_to_many :authors, :class_name=>'Person' has_and_belongs_to_many :editors, :class_name=>'Person' end The above code doesn't work, because it uses the same join table. Now I now that I can specify the name of the join table, but there is a warning in the API documentation is a warning about that which I don't understand: :join_table: Specify the name of the join table if the default based on lexical order isn’t what you want. WARNING: If you’re overwriting the table name of either class, the table_name method MUST be declared underneath any has_and_belongs_to_many declaration in order to work.

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  • Is it possible to reference object within the same object?

    - by fudgey
    I've been messing around with jQuery plugin code and I'm trying to put all of my common variables into a single object for easy access. I have included a few examples below on how I've done this, but I'm wondering how others deal with this problem. Lets say I have this var x = function(options){ var defaults = { ulist : $('ul#list'), listLen : $('ul#list').children().length } $.extend(options, defaults); // do other stuff } What I'm trying to do is use the ulist object in as a base, then find the number of li's I guess I could do this: var x = function(options){ var defaults = { ulist : $('ul#list'), listLen : 0 } defaults.listLen = defaults.ulist.children().length; $.extend(options, defaults); // do other stuff } or this: var x = function(options){ var defaults = { ulist : $('ul#list') }; var defaults2 = { listLen : defaults.ulist.children().length } $.extend(defaults, defaults2); $.extend(options, defaults); // do other stuff } The above code samples are just thrown together, and only meant to get the idea across to you. Anyway, is there a better way to do this?

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  • $(MSBuildStartupDirectory) in Visual Studio points to different places on different machines

    - by skolima
    In a large solution, I'm integrating Gendarme into Visual Studio 2008 compilation process. I am using GendarmeMsBuild task along with a .targets file to add a AfterBuild target to every project in the solution. I am looking for a way to import this file into .csproj files in a way that wouldn't require me to change the include path (the projects have different nesting levels). Apart from using NuGet SolutionDir variable, best way to solve this seemed to be to use $(MSBuildStartupDirectory). However, as it turns out, on some machines, using the same version of VS 2008 (as same updates installed, as far as I was able to check) this resolves to the solution directory, and on others to c:\Program Files (x86)\Microsoft Visual Studio 9.0\Common7\IDE. How can I either get this to always resolve to the solution folder or obtain the base folder in another consistent way?

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  • NameError in CompetitorsController#index

    - by manish nautiyal
    Hi all I am getting this problem when I run this code in server. In my localhost everything is running fine. But when I deploy my code in the server it shows me the error. I am using FERRET SERARCH IN MODEL. NameError in CompetitorsController#index uninitialized constant CompetitorsController::Competitor /opt/ruby_enterprise/lib/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:102:in `const_missing' /home/troche/mrecip_tool/releases/20091219131859/app/controllerscompetitors_controller .rb :19:in `index' My controller is class CompetitorsController < ApplicationController include AuthenticatedSystem layout 'application' auto_complete_for :proscribed, :competitor auto_complete_for :fee_earner, :fee_earner protect_from_forgery :only = [:tag] before_filter :login_required, :only = [:index, :show, :new, :edit] @@total_company = 70 def index @compet = Competitor.find(:all) ### GETTING ERROR IN THIS LINE respond_to do |format| format.html # index.html.erb format.xml { render :xml => @compet } end end def show @competitor = Competitor.find(params[:id]) respond_to do |format| format.html # show.html.erb format.xml { render :xml => @competitor } end end end My Model is class Competitor < ActiveRecord::Base validates_presence_of :fee_earner_id, :notes belongs_to :fee_earner belongs_to :country belongs_to :state belongs_to :user acts_as_ferret :fields =[:competitor, :client, :subject_matter],:remote = true end

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  • Question About Abstract Classes?

    - by IbrarMumtaz
    URL: Link (1) According to this wesbite .. you cannot implement Abstract classes but derive from them. This makes sense and I have read this many times. Like an interface, you cannot implement an instance of an abstract class, however you can implement methods, fields, and properties in the abstract class that can be used by the child class. But on MSDN URL: TextWriter CLass on MSDN TextWriter is an abstract class but it has two constructors defined ... and according to the MS 70-536 book, the following statement is valid: TextWriter tw = new File.CreateText("myFile.Txt") The static file class and it's CreateText method is fine by me as I have studied it on MSDN but can somebody explain this little contradiction I have found? Surely I am not the first? Why is instantaion of base abstract classes possible????

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  • links in codeigniter

    - by Patrick
    hi All, I'm experimenting with codeigniter but don't really understand how links work. for example, I have a link like this: localhost/ci/welcome/cat/7 My base url is localhost/ci, so by clicking on this link I would expect the method "cat" of controller "welcome" to be called. This method is very simple: function cat() { echo "just a test."; } Pretty basic - I would expect to see the text on screen, but I just see a 404 -page not found error. What could be the problem?

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  • "Personal" method in ruby

    - by steve gooberman-hill
    I'm looking for a way of making a method "personal" - note NOT PRIVATE to a class here is an example - by "personal" I mean the behaviour of method "foo" class A def foo "foo" end end class B < A def foo "bar" end end class C < B end a=A.new; b=B.new;c=C.new I'm looking for a way of producing the following behaviour a.foo #=> "foo" b.foo #=> "bar" c.foo #=> "foo" (ultimate base class method called) Any ideas? Thanks Steve

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  • Convert executed SQL result to a list of Model object

    - by huynq9
    I'm wondering that is it possible to convert the executed query result to a list of models. I'm using Ruby with ActiveRecord and need to execute custom SQL query to join two or many tables. The code looks like below: connection = ActiveRecord::Base.connection sql = "select T1.f1, T2.f2 from T1 left join T2 on T1.id = T2.id" @result = connection.execute(sql) In Ruby code, I defined a models to manage the executed SQL result: class Model property :f1, :f2 end Is there any way to convert @result to list of Model object? so I can deal with each item in the list as following @result.each do |item| puts item.f1 puts item.f2 end

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  • C++ initializing constants and inheritance

    - by pingvinus
    I want to initialize constant in child-class, instead of base class. And use it to get rid of dynamic memory allocation (I know array sizes already, and there will be a few child-classes with different constants). So I try: class A { public: const int x; A() : x(0) {} A(int x) : x(x) {} void f() { double y[this->x]; } }; class B : A { B() : A(2) {} }; Pretty simple, but compiler says: error C2057: expected constant expression How can I say to compiler, that it is really a constant?

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  • Create generic class instance throws TypeLoadException

    - by Elisa
    My TestLayer class has the namespace: "BLL.Infrastructure.TestLayer" and is inside the assembly: "BLL" public class LayerFactory<T, U> { public static IBaseLayer<T, U> Get() { var obj = Activator.CreateInstance("BLL", "BLL.Infrastructure.TestLayer", new object[] { (IBaseLayer<T, U>)null }); } } When I run the code the Activator throws an TypeLoadException with no more details Thats the concrete class it should create: GenericBaseLayer implements the IBaseLayer. public class TestLayer<T, U> : GenericBaseLayer<MyRequest, MyInfo.ActionType> { public TestLayer(IBaseLayer<MyRequest, MyInfo.ActionType> layer) : base(layer) { } } What do I wrong?

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  • Create Generic Class Instance from Static Method in a Derived Class

    - by user343547
    I have a class in C# with a template and static method similar to class BClass<T> { public static BClass<T> Create() { return new BClass<T>(); } } From this I derive a class and specify a template parameter to the base class class DClass : BClass<int> { } A problem occurs when I try to use the static method to create an instance of D class Program { static void Main(string[] args) { DClass d = DClass.Create(); } } Gives a compiler error "Cannot implicitly convert type 'Test.BClass<int ' to 'Test.DClass'." Adding the below cast leads to a runtime casting exception. DClass d = (DClass)DClass.Create(); Is there any succint way to allow the static method to create instances of the derived class? Ideally I would like the equivalent of a c++ typedef and I don't want the below syntax (which does work). BClass<int> d = DClass.Create();

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  • How can a Delphi TPersistent object calculate its own deserialization time?

    - by mjustin
    For performance tests I need a way to measure the time needed for a form to load its definition from the DFM. All existing forms inherit a custom form class. To capture the current time, this base class needs overriden methods as "extension points": start of the deserialization process after the deserialization (can be implemented by overriding the Loaded procedure) the moment just before the execution of the OnFormCreate event So the log for TMyForm.Create(nil) could look like: - 00.000 instance created - 00.010 before deserialization - 01.823 after deserialization - 02.340 before OnFormCreate Which TObject (or TComponent) methods are best suited? Maybe there are other extension points in the form creation process, please feel free to make suggestions.

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  • How would you create a string of all UTF-8 characters? [PHP]

    - by Xeoncross
    There are many ways to represent the +1 million UTF-8 characters. Take the latin capital "A" with macron (A). This is unicode code point U+0100, hex number 0xc4 0x80, decimal number 196 128, and binary 11000100 10000000. I would like to create a collection of the first 65,535 UTF-8 characters for use in testing applications. These are all unicode characters up to code point U+FFFF (byte3). Is it possible to do something like a for($x=0) loop and then convert the resulting decimal to another base (like hex) which would allow the creation of the matching unicode character? I can create the value A using something like this: $char = "\xc4\x80"; // or $char = chr(196).chr(128); However, I am not sure how to turn this into an automated process. // fail! $char = "\x". dechex($a). "\x". dexhex($$b);

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  • Accessing Session and IPrinciple data in a Master View in Asp.Net MCV

    - by bplus
    I currently have a abstract controller class that I all my controllers inherit from. In my master page I want to be able to access some data that will be in Session and also the currently user (IPrinciple). I read that I could use the contructor of by abstract base controller class, that is I could do something like public BaseController() { ViewData["SomeData"] = Session["SomeData"]; ViewData["UserName"] = this.User.Identity.Name; } I could then access ViewData["UserName"] etc from my master page. My problem is that both Session and User are null at this point. Does anybody know of a different approach? Thanks in advance.

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  • Building Boost with LSB C++ Compiler

    - by Alex Farber
    I want to build my program with LSB C++ Compiler from the Linux Standard Base http://www.linuxfoundation.org/collaborate/workgroups/lsb. Program depends on the Boost library, built with gcc 4.4 version. Compilation fails. Is it possible to build the Boost library with LSB C++ Compiler? Alternatively, is it possible to build the Boost library with some old gcc version, what version is recommended? My final goal is to get my executable and third-party Boost libraries running on most Linux distributions. Generally, what can be done to get better binary compatibility for Linux distributions, developing C++ closed-source application depending on the Boost library?

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  • C++ vtable resolving with virtual inheritance

    - by Tomas Cokis
    I was curious about C++ and virtual inheritance - in particular, the way that vtable conflicts are resolved between bass and child classes. I won't pretend to understand the specifics on how they work, but what I've gleamed so far is that their is a small delay caused by using virtual functions due to that resolution. My question then is if the base class is blank - ie, its virtual functions are defined as: virtual void doStuff() = 0; Does this mean that the resolution is not necessary, because there's only one set of functions to pick from? Forgive me if this is an stupid question - as I said, I don't understand how vtables work so I don't really know any better.

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  • Record audio via MediaRecorder

    - by Isuru Madusanka
    I am trying to record audio by MediaRecorder, and I get an error, I tried to change everything and nothing works. Last two hours I try to find the error, I used Log class too and I found out that error occurred when it call recorder.start() method. What could be the problem? public class AudioRecorderActivity extends Activity { MediaRecorder recorder; File audioFile = null; private static final String TAG = "AudioRecorderActivity"; private View startButton; private View stopButton; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); startButton = findViewById(R.id.start); stopButton = findViewById(R.id.stop); setContentView(R.layout.main); } public void startRecording(View view) throws IOException{ startButton.setEnabled(false); stopButton.setEnabled(true); File sampleDir = Environment.getExternalStorageDirectory(); try{ audioFile = File.createTempFile("sound", ".3gp", sampleDir); }catch(IOException e){ Toast.makeText(getApplicationContext(), "SD Card Access Error", Toast.LENGTH_LONG).show(); Log.e(TAG, "Sdcard access error"); return; } recorder = new MediaRecorder(); recorder.setAudioSource(MediaRecorder.AudioSource.MIC); recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP); recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB); recorder.setAudioEncodingBitRate(16); recorder.setAudioSamplingRate(44100); recorder.setOutputFile(audioFile.getAbsolutePath()); recorder.prepare(); recorder.start(); } public void stopRecording(View view){ startButton.setEnabled(true); stopButton.setEnabled(false); recorder.stop(); recorder.release(); addRecordingToMediaLibrary(); } protected void addRecordingToMediaLibrary(){ ContentValues values = new ContentValues(4); long current = System.currentTimeMillis(); values.put(MediaStore.Audio.Media.TITLE, "audio" + audioFile.getName()); values.put(MediaStore.Audio.Media.DATE_ADDED, (int)(current/1000)); values.put(MediaStore.Audio.Media.MIME_TYPE, "audio/3gpp"); values.put(MediaStore.Audio.Media.DATA, audioFile.getAbsolutePath()); ContentResolver contentResolver = getContentResolver(); Uri base = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; Uri newUri = contentResolver.insert(base, values); sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, newUri)); Toast.makeText(this, "Added File" + newUri, Toast.LENGTH_LONG).show(); } } And here is the xml layout. <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/RelativeLayout1" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <Button android:id="@+id/start" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" android:layout_marginTop="146dp" android:onClick="startRecording" android:text="Start Recording" /> <Button android:id="@+id/stop" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/start" android:layout_below="@+id/start" android:layout_marginTop="41dp" android:enabled="false" android:onClick="stopRecording" android:text="Stop Recording" /> </RelativeLayout> And I added permission to AndroidManifest file. <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="in.isuru.audiorecorder" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="8" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" > <activity android:name=".AudioRecorderActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.RECORD_AUDIO" /> </manifest> I need to record high quality audio. Thanks!

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  • Python metaprogramming help

    - by Timmy
    im looking into mongoengine, and i wanted to make a class an "EmbeddedDocument" dynamically, so i do this def custom(cls): cls = type( cls.__name__, (EmbeddedDocument,), cls.__dict__.copy() ) cls.a = FloatField(required=True) cls.b = FloatField(required=True) return cls A = custom( A ) and tried it on some classes, but its not doing some of the base class's init or sumthing in BaseDocument def __init__(self, **values): self._data = {} # Assign initial values to instance for attr_name, attr_value in self._fields.items(): if attr_name in values: setattr(self, attr_name, values.pop(attr_name)) else: # Use default value if present value = getattr(self, attr_name, None) setattr(self, attr_name, value) but this never gets used, thus never setting ._data, and giving me errors. how do i do this?

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  • Recursion Interview Questions [closed]

    - by halivingston
    Given a string, "ABC", print all permutations Given a dollar bill, fill out possible ways it can summed up using .25, .10, .5, etc. Given a phone number (123-456), print out all it's word counter parters like (ADG-XYZ) A B C D E F G H I J K L M N O P In the above 2D matrix, print all possible words (just literally all words, and sure we could check if it's exists in a dictionary). The base case is I think here is that reaching the same i, j positions. Any others you can think of?

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  • Is this physical collection class that contains only static methods an Anti-Pattern?

    - by Tj Kellie
    I'm trying to figure out if I should continue on with a current pattern in an application I'm working in, or refactor this into something else. I have a set of collection classes off a generic base of List. These classes have public constructors but contain only static methods that return collections. They look like this: public class UserObjCollection : BaseCollection<UserObj> { public static UserObjCollection GetAllUserObj() { UserObjCollection obj = new UserObjCollection(); obj.MapObjects(new UserObjDataService().GetAllUserObj()); return obj; } } Is this a Pattern or Anti-Pattern and what are the merits of this over a straight factory pattern?

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  • Setting package-wide variables during python setup.py install

    - by Morgoth
    Is there a way that when a user types python setup.py install to install a Python package, setup.py can be made to set specific variables at the base of the pacakge? A common example would be to basically set mypackage.__revision__ to be the svn revision of the checkout if one is working from svn. Another example case would be if the user can choose a global option, so that the option mypackage.__option__ be set according to a flag passed to setup.py, e.g. python setup.py install --set-flag=10 Then when using the package, mypackage.__option__ would equal 10.

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