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  • How to Factory Reset Your Android Phone or Tablet When It Won’t Boot

    - by Chris Hoffman
    Safe mode can help you troubleshoot your Android, but sometimes you’ll need to wipe everything and restore your device to its factory state. You can even perform a factory reset when your Android phone or tablet won’t boot normally. Ensure you have any important data backed up before doing a reset. This includes your Google Authenticator credentials, which will be lost during the reset. Disable two-factor authentication on your accounts first or you’ll experience some trouble afterwards. How to Factory Reset Your Android Phone or Tablet When It Won’t Boot Our Geek Trivia App for Windows 8 is Now Available Everywhere How To Boot Your Android Phone or Tablet Into Safe Mode

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  • Inside the Raspberry Pi Factory

    - by Jason Fitzpatrick
    Curious where your pint-sized Raspberry Pi came from? You might be surprised to learn it was built, tested, and packaged all in an equally pint-sized factory in South Wales. Nick Heath of Tech Republic takes us on a photo tour of the Raspberry Pi factory with a stop at each stage of production and testing. The photo above shows one of the manual construction steps, the insertion of the large components such as the USB and Ethernet ports. Hit up the link below for the full tour. Raspberry Pi: Inside the Pi Factory [Tech Republic] Our Geek Trivia App for Windows 8 is Now Available Everywhere How To Boot Your Android Phone or Tablet Into Safe Mode HTG Explains: Does Your Android Phone Need an Antivirus?

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  • Game Object Factory: Fixing Memory Leaks

    - by Bunkai.Satori
    Dear all, this is going to be tough: I have created a game object factory that generates objects of my wish. However, I get memory leaks which I can not fix. Memory leaks are generated by return new Object(); in the bottom part of the code sample. static BaseObject * CreateObjectFunc() { return new Object(); } How and where to delete the pointers? I wrote bool ReleaseClassType(). Despite the factory works well, ReleaseClassType() does not fix memory leaks. bool ReleaseClassTypes() { unsigned int nRecordCount = vFactories.size(); for (unsigned int nLoop = 0; nLoop < nRecordCount; nLoop++ ) { // if the object exists in the container and is valid, then render it if( vFactories[nLoop] != NULL) delete vFactories[nLoop](); } return true; } Before taking a look at the code below, let me help you in that my CGameObjectFactory creates pointers to functions creating particular object type. The pointers are stored within vFactories vector container. I have chosen this way because I parse an object map file. I have object type IDs (integer values) which I need to translate them into real objects. Because I have over 100 different object data types, I wished to avoid continuously traversing very long Switch() statement. Therefore, to create an object, I call vFactoriesnEnumObjectTypeID via CGameObjectFactory::create() to call stored function that generates desired object. The position of the appropriate function in the vFactories is identical to the nObjectTypeID, so I can use indexing to access the function. So the question remains, how to proceed with garbage collection and avoid reported memory leaks? #ifndef GAMEOBJECTFACTORY_H_UNIPIXELS #define GAMEOBJECTFACTORY_H_UNIPIXELS //#include "MemoryManager.h" #include <vector> template <typename BaseObject> class CGameObjectFactory { public: // cleanup and release registered object data types bool ReleaseClassTypes() { unsigned int nRecordCount = vFactories.size(); for (unsigned int nLoop = 0; nLoop < nRecordCount; nLoop++ ) { // if the object exists in the container and is valid, then render it if( vFactories[nLoop] != NULL) delete vFactories[nLoop](); } return true; } // register new object data type template <typename Object> bool RegisterClassType(unsigned int nObjectIDParam ) { if(vFactories.size() < nObjectIDParam) vFactories.resize(nObjectIDParam); vFactories[nObjectIDParam] = &CreateObjectFunc<Object>; return true; } // create new object by calling the pointer to the appropriate type function BaseObject* create(unsigned int nObjectIDParam) const { return vFactories[nObjectIDParam](); } // resize the vector array containing pointers to function calls bool resize(unsigned int nSizeParam) { vFactories.resize(nSizeParam); return true; } private: //DECLARE_HEAP; template <typename Object> static BaseObject * CreateObjectFunc() { return new Object(); } typedef BaseObject*(*factory)(); std::vector<factory> vFactories; }; //DEFINE_HEAP_T(CGameObjectFactory, "Game Object Factory"); #endif // GAMEOBJECTFACTORY_H_UNIPIXELS

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  • How do I restore a Dell Inspiron 1521 laptop to factory defaults?

    - by Solignis
    I got a Dell Inspiron 1521 laptop from a local computer store that a buddy of mine works at. When I turned it on I had come to realize it has not been wiped and reverted to factory defaults. How can revert the machine to factory defaults? I do not have any of the CDs that came with the machine, all I have is the computer and the power brick. But if it helps any I can able to get into Windows so I full access to the machine.

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  • iPad: How To Soft Reset, Restore Factory Settings And Erase All Content

    - by Gopinath
    iPad is an amazing gadget from Apple and everyone of us loves to own it. If you are a lucky one to own an iPad here are some basic troubleshooting features that you should be aware. There is no doubt that iPad is an amazing gadget, but similar to other electronic gadgets it refuses to work now and then. When your iPad hangs or refuses to respond you can soft reset it by holding the Sleep/Wake button and the Home button at the same time for at least ten seconds, until the Apple logo appears. This just reset your iPad and it’s similar to force rebooting your PC. All your settings and data are untouched during this process. The embedded video below shows how to turn off and soft reset an iPad. If iPad Doesn’t Work After Soft Reset – Restore Factory Settings Soft reset should resolve most of the iPad issues like hanging, not responding properly, etc. In case even if your iPad does not work properly after soft reset you can try reset all the setting to factory defaults by navigating through the Home screen > Settings > General > Reset > Reset All Settings.  This will reset all your settings and other iPad customizations to factory defaults but your data(images, documents, apps, etc.) are left untouched. How To Erase All Content Of iPad You may ask why should I erase all the content of iPad? Well may be you are willing to sell it off on eBay by erasing all the content or you want start afresh or some other reason. It is easy to reset all the settings of iPad as well as wipe out all content by navigating through Home screen > General > Reset >  “Erase All Content and Settings.” CC Image credit flickr/korosirego This article titled,iPad: How To Soft Reset, Restore Factory Settings And Erase All Content, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • What is this Design Pattern?

    - by Can't Tell
    I read the Wikipedia articles on FactoryMethod and AbstractFactory but the following code doesn't seem to fit anywhere. Can someone explain to me what the following pattern is or if it is an anti-pattern? interace PaymentGateway{ void makePayment(); } class PaypalPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class AuthorizeNetPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class PaymentGatewayFacotry{ PaymentGateway createPaymentGateway(int gatewayId) { if(gatewayId == 1) return PaypalPaymentGateway(); else if(gatewayId == 2) return AuthorizeNetPaymentGateway(); } } Let's say the user selects the payment method using a radio button on an html page and the gatewayId is derived from the radio button value. I have seen code like this and thought it was the AbstractFactory pattern but after reading the Wikipedia article, I'm having doubts.

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  • Little girl friendly versions of Linux (or themes for Linux)

    - by Hamish Downer
    I'm going to install Linux on a PC for a daughter (age 7) of a friend of mine. I recently came across Hannah Montana Linux. The parents don't want a commercially branded thing going on, so no Hannah Montana. But I was wondering if there were other linux distros - or desktop themes - that would be cool for a 7 year old girl. All suggestions welcome.

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  • Is is possible to create a factory class in PHP?

    - by user198729
    Like the BeanFactory in java: In the much more common case where the BeanFactory itself directly creates the bean by calling its constructor (equivalent to Java code calling new), the class attribute specifies the class of the bean to be constructed. In the less common case where the BeanFactory calls a static, so-called factory method on a class to create the bean, the class attribute specifies the actual class containing the static factory method. Note:it's not the factory method

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  • CEO Taken Captive in His Own Factory?

    - by Stephen Slade
    Last Friday was no ordinary day for Chip Starnes, the 42 year old factory owner of Specialty Medical Supplies in China. He recently announced movement of some of the production of their diabetes testing equipment from Beijing to Mumbai India.  Of the 110 employees at the facility, about 80 protested by blocking the doors and refusing to let Chip Starnes out of the facility.  He has been trapped in his office several days now.  The employees think the factory was closing but Mr. Starnes said it was not. Mis-information? Poor communications? Work-stoppage. This is a good example of supply chain disruption. Parked cars are blocking the entrance to the facility, front gates are chained close, the CEO a prisoner in his own factory. Chip Starnes was presented with documents to sign in Chinese indicating he would pay severance and other demands he did not understand, possibly bankrupting the company.    If you depend on supply from China and other foreign suppliers, how reliable are your sources? For example how are the shopfloor employee relations? Is it possible to predict these types of HR risks and plan around them? What are your contingencies? It's important to ask the right questions and hear good answers. Having tools in place to rapidly evaluate, assess and react to these disruptions are the keys to survival. Hear how leading organizations are reinforcing their supply chains and mitigating risk through technology with Oracle's latest release of Oracle Supply Chain Management. Source: WSJ pg.B1, June 25, 2013

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  • Looking for a better Factory pattern (Java)

    - by Sam Goldberg
    After doing a rough sketch of a high level object model, I am doing iterative TDD, and letting the other objects emerge as a refactoring of the code (as it increases in complexity). (That whole approach may be a discussion/argument for another day.) In any case, I am at the point where I am looking to refactor code blocks currently in an if-else blocks into separate objects. This is because there is another another value combination which creates new set of logical sub-branches. To be more specific, this is a trading system feature, where buy orders have different behavior than sell orders. Responses to the orders have a numeric indicator field which describes some event that occurred (e.g. fill, cancel). The combination of this numeric indicator field plus whether it is a buy or sell, require different processing buy the code. Creating a family of objects to separate the code for the unique handling each of the combinations of the 2 fields seems like a good choice at this point. The way I would normally do this, is to create some Factory object which when called with the 2 relevant parameters (indicator, buysell), would return the correct subclass of the object. Some times I do this pattern with a map, which allows to look up a live instance (or constructor to use via reflection), and sometimes I just hard code the cases in the Factory class. So - for some reason this feels like not good design (e.g. one object which knows all the subclasses of an interface or parent object), and a bit clumsy. Is there a better pattern for solving this kind of problem? And if this factory method approach makes sense, can anyone suggest a nicer design?

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  • Rails Controller Tests for Captcha using Shoulda, Factory Girl, Mocha

    - by Siva
    Can someone provide a strategy/code samples/pointers to test Captcha validations + Authlogic using Shoulda, Factory Girl and Mocha? For instance, my UsersController is something like: class UsersController < ApplicationController validates_captcha ... def create ... if captcha_validated? # code to deal with user attributes end ... end In this case, how do you mock/stub using Shoulda / Factory Girl / Mocha to test valid and invalid responses to the Captcha image? Appreciate your help, Siva

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  • Arbitrary attributes error with has_one association and Factory Girl

    - by purpletonic
    I'm trying to build a basic shopping cart for a Rails app I'm working on. Nothing special, - the shopping cart has many line_items - each line_item has_one product associated and a quantity with it class Cart < ActiveRecord::Base attr_accessible :line_items has_many :line_items, :dependent => :destroy end class LineItem < ActiveRecord::Base attr_accessible :quantity, :product belongs_to :cart has_one :product end I'm trying to use RSpec to test this association, but i'm doing something wrong as I'm getting an error that says: DEPRECATION WARNING: You're trying to create an attribute 'line_item_id'. Writing arbitrary attributes on a model is deprecated, and I'm not sure why. In my factories.rb file I'm defining the line_item factory as follows: factory :line_item do quantity { Random.rand(1..5) } product end factory :cart do factory :cart_with_two_line_items do ignore do line_item_count 2 end after(:create) do |cart, evaluator| FactoryGirl.create_list(:line_item, evaluator.line_item_count, cart_id: cart) end end end Any pointers where I'm going wrong, it's probably something basic, but I'm still quite new to Rspec. Thanks in advance.

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  • Factory Girl: Automatically assigning parent objects

    - by Ben Scheirman
    I'm just getting into Factory Girl and I am running into a difficulty that I'm sure should be much easier. I just couldn't twist the documentation into a working example. Assume I have the following models: class League < ActiveRecord::Base has_many :teams end class Team < ActiveRecord::Base belongs_to :league has_many :players end class Player < ActiveRecord::Base belongs_to :team end What I want to do is this: team = Factory.build(:team_with_players) and have it build up a bunch of players for me. I tried this: Factory.define :team_with_players, :class => :team do |t| t.sequence {|n| "team-#{n}" } t.players {|p| 25.times {Factory.build(:player, :team => t)} } end But this fails on the :team=>t section, because t isn't really a Team, it's a Factory::Proxy::Builder. I have to have a team assigned to a player. In some cases I want to build up a League and have it do a similar thing, creating multiple teams with multiple players. What am I missing?

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  • Oracle: Addressing Information Overload in Factory Automation

    - by [email protected]
     ORACLE's Stephen Slade has written about addressing information overload on the factory floor.  According to Slade, today's automated processes create large amounts of valuable data, but only a small percentage remains actionable.Oracle claims information overload can cost financially, as companies struggle to store and collect reams of data needed to identify embedded trends, while producing manual reports to meet quality standards, regulatory requirements and general reporting goals.Increasing scrutiny of new requirements and standards add to the need to find new ways to process data. Many companies are now using analytical engines to contextualise data into 'actionable information'. Oracle claims factories need to seriously address their data collection, audit trail and records retention processes. By organising their data, factories can maximise outcomes from excellence and contuinuous improvement programs, and gain visibility into costs int the supply chain.Analytics tools and technologies such as Business Intelligence (BI), Enterprise Manufacturing Intelligence (EMI) and Manufacturing Operations Centers (MOC) can help consolidate, contextual and distribute information.   FULL ARICLE:  http://www.myfen.com.au/news/oracle--addressing-information-overload-in-factory

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  • Is it possible to create a C++ factory system that can create an instance of any "registered" object

    - by chrensli
    Hello, I've spent my entire day researching this topic, so it is with some scattered knowledge on the topic that i come to you with this inquiry. Please allow me to describe what I am attempting to accomplish, and maybe you can either suggest a solution to the immediate question, or another way to tackle the problem entirely. I am trying to mimic something related to how XAML files work in WPF, where you are essentially instantiating an object tree from an XML definition. If this is incorrect, please inform. This issue is otherwise unrelated to WPF, C#, or anything managed - I solely mention it because it is a similar concept.. So, I've created an XML parser class already, and generated a node tree based on ObjectNode objects. ObjectNode objects hold a string value called type, and they have an std::vector of child ObjectNode objects. The next step is to instantiate a tree of objects based on the data in the ObjectNode tree. This intermediate ObjectNode tree is needed because the same ObjectNode tree might be instantiated multiple times or delayed as needed. The tree of objects that is being created is such that the nodes in the tree are descendants of a common base class, which for now we can refer to as MyBase. Leaf nodes can be of any type, not necessarily derived from MyBase. To make this more challenging, I will not know what types of MyBase derived objects might be involved, so I need to allow for new types to be registered with the factory. I am aware of boost's factory. Their docs have an interesting little design paragraph on this page: o We may want a factory that takes some arguments that are forwarded to the constructor, o we will probably want to use smart pointers, o we may want several member functions to create different kinds of objects, o we might not necessarily need a polymorphic base class for the objects, o as we will see, we do not need a factory base class at all, o we might want to just call the constructor - without #new# to create an object on the stack, and o finally we might want to use customized memory management. I might not be understanding this all correctly, but that seems to state that what I'm trying to do can be accomplished with boost's factory. But all the examples I've located, seem to describe factories where all objects are derived from a base type. Any guidance on this would be greatly appreciated. Thanks for your time!

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  • When is factory method better than simple factory and vice versa?

    - by Bruce
    Hi all Working my way through the Head First Design Patterns book. I believe I understand the simple factory and the factory method, but I'm having trouble seeing what advantages factory method brings over simple factory. If an object A uses a simple factory to create its B objects, then clients can create it like this: A a = new A(new BFactory()); whereas if an object uses a factory method, a client can create it like this: A a = new ConcreteA(); // ConcreteA contains a method for instantiating the same Bs that the BFactory above creates, with the method hardwired into the subclass of A, ConcreteA. So in the case of the simple factory, clients compose A with a B factory, whereas with the factory method, the client chooses the appropriate subclass for the types of B it wants. There really doesn't seem to be much to choose between them. Either you have to choose which BFactory you want to compose A with, or you have to choose the right subclass of A to give you the Bs. Under what circumstances is one better than the other? Thanks all!

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  • Caching factory design

    - by max
    I have a factory class XFactory that creates objects of class X. Instances of X are very large, so the main purpose of the factory is to cache them, as transparently to the client code as possible. Objects of class X are immutable, so the following code seems reasonable: # module xfactory.py import x class XFactory: _registry = {} def get_x(self, arg1, arg2, use_cache = True): if use_cache: hash_id = hash((arg1, arg2)) if hash_id in _registry: return _registry[hash_id] obj = x.X(arg1, arg2) _registry[hash_id] = obj return obj # module x.py class X: # ... Is it a good pattern? (I know it's not the actual Factory Pattern.) Is there anything I should change? Now, I find that sometimes I want to cache X objects to disk. I'll use pickle for that purpose, and store as values in the _registry the filenames of the pickled objects instead of references to the objects. Of course, _registry itself would have to be stored persistently (perhaps in a pickle file of its own, in a text file, in a database, or simply by giving pickle files the filenames that contain hash_id). Except now the validity of the cached object depends not only on the parameters passed to get_x(), but also on the version of the code that created these objects. Strictly speaking, even a memory-cached object could become invalid if someone modifies x.py or any of its dependencies, and reloads it while the program is running. So far I ignored this danger since it seems unlikely for my application. But I certainly cannot ignore it when my objects are cached to persistent storage. What can I do? I suppose I could make the hash_id more robust by calculating hash of a tuple that contains arguments arg1 and arg2, as well as the filename and last modified date for x.py and every module and data file that it (recursively) depends on. To help delete cache files that won't ever be useful again, I'd add to the _registry the unhashed representation of the modified dates for each record. But even this solution isn't 100% safe since theoretically someone might load a module dynamically, and I wouldn't know about it from statically analyzing the source code. If I go all out and assume every file in the project is a dependency, the mechanism will still break if some module grabs data from an external website, etc.). In addition, the frequency of changes in x.py and its dependencies is quite high, leading to heavy cache invalidation. Thus, I figured I might as well give up some safety, and only invalidate the cache only when there is an obvious mismatch. This means that class X would have a class-level cache validation identifier that should be changed whenever the developer believes a change happened that should invalidate the cache. (With multiple developers, a separate invalidation identifier is required for each.) This identifier is hashed along with arg1 and arg2 and becomes part of the hash keys stored in _registry. Since developers may forget to update the validation identifier or not realize that they invalidated existing cache, it would seem better to add another validation mechanism: class X can have a method that returns all the known "traits" of X. For instance, if X is a table, I might add the names of all the columns. The hash calculation will include the traits as well. I can write this code, but I am afraid that I'm missing something important; and I'm also wondering if perhaps there's a framework or package that can do all of this stuff already. Ideally, I'd like to combine in-memory and disk-based caching.

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  • Factory Girl Association

    - by David Lyod
    I have an association of a Admin - Account in factory girl I now wish to associate a second user with the same account but am unable to do so. I build my Admin-Account association like this u.account { |account| account.association(:account)} This works fine and creates the Account and Admin association. Im looking for a way to setup a second user who's account also points to the record created in the Admin factory association. I currently just build the second user as such @user = Factory.build(:seconduser) @user.account = Account.first @user.save! Which works but seems somewhat hacky .

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  • C#/.NET Little Wonders: Tuples and Tuple Factory Methods

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can really help improve your code by making it easier to write and maintain.  This week, we look at the System.Tuple class and the handy factory methods for creating a Tuple by inferring the types. What is a Tuple? The System.Tuple is a class that tends to inspire a reaction in one of two ways: love or hate.  Simply put, a Tuple is a data structure that holds a specific number of items of a specific type in a specific order.  That is, a Tuple<int, string, int> is a tuple that contains exactly three items: an int, followed by a string, followed by an int.  The sequence is important not only to distinguish between two members of the tuple with the same type, but also for comparisons between tuples.  Some people tend to love tuples because they give you a quick way to combine multiple values into one result.  This can be handy for returning more than one value from a method (without using out or ref parameters), or for creating a compound key to a Dictionary, or any other purpose you can think of.  They can be especially handy when passing a series of items into a call that only takes one object parameter, such as passing an argument to a thread's startup routine.  In these cases, you do not need to define a class, simply create a tuple containing the types you wish to return, and you are ready to go? On the other hand, there are some people who see tuples as a crutch in object-oriented design.  They may view the tuple as a very watered down class with very little inherent semantic meaning.  As an example, what if you saw this in a piece of code: 1: var x = new Tuple<int, int>(2, 5); What are the contents of this tuple?  If the tuple isn't named appropriately, and if the contents of each member are not self evident from the type this can be a confusing question.  The people who tend to be against tuples would rather you explicitly code a class to contain the values, such as: 1: public sealed class RetrySettings 2: { 3: public int TimeoutSeconds { get; set; } 4: public int MaxRetries { get; set; } 5: } Here, the meaning of each int in the class is much more clear, but it's a bit more work to create the class and can clutter a solution with extra classes. So, what's the correct way to go?  That's a tough call.  You will have people who will argue quite well for one or the other.  For me, I consider the Tuple to be a tool to make it easy to collect values together easily.  There are times when I just need to combine items for a key or a result, in which case the tuple is short lived and so the meaning isn't easily lost and I feel this is a good compromise.  If the scope of the collection of items, though, is more application-wide I tend to favor creating a full class. Finally, it should be noted that tuples are immutable.  That means they are assigned a value at construction, and that value cannot be changed.  Now, of course if the tuple contains an item of a reference type, this means that the reference is immutable and not the item referred to. Tuples from 1 to N Tuples come in all sizes, you can have as few as one element in your tuple, or as many as you like.  However, since C# generics can't have an infinite generic type parameter list, any items after 7 have to be collapsed into another tuple, as we'll show shortly. So when you declare your tuple from sizes 1 (a 1-tuple or singleton) to 7 (a 7-tuple or septuple), simply include the appropriate number of type arguments: 1: // a singleton tuple of integer 2: Tuple<int> x; 3:  4: // or more 5: Tuple<int, double> y; 6:  7: // up to seven 8: Tuple<int, double, char, double, int, string, uint> z; Anything eight and above, and we have to nest tuples inside of tuples.  The last element of the 8-tuple is the generic type parameter Rest, this is special in that the Tuple checks to make sure at runtime that the type is a Tuple.  This means that a simple 8-tuple must nest a singleton tuple (one of the good uses for a singleton tuple, by the way) for the Rest property. 1: // an 8-tuple 2: Tuple<int, int, int, int, int, double, char, Tuple<string>> t8; 3:  4: // an 9-tuple 5: Tuple<int, int, int, int, double, int, char, Tuple<string, DateTime>> t9; 6:  7: // a 16-tuple 8: Tuple<int, int, int, int, int, int, int, Tuple<int, int, int, int, int, int, int, Tuple<int,int>>> t14; Notice that on the 14-tuple we had to have a nested tuple in the nested tuple.  Since the tuple can only support up to seven items, and then a rest element, that means that if the nested tuple needs more than seven items you must nest in it as well.  Constructing tuples Constructing tuples is just as straightforward as declaring them.  That said, you have two distinct ways to do it.  The first is to construct the tuple explicitly yourself: 1: var t3 = new Tuple<int, string, double>(1, "Hello", 3.1415927); This creates a triple that has an int, string, and double and assigns the values 1, "Hello", and 3.1415927 respectively.  Make sure the order of the arguments supplied matches the order of the types!  Also notice that we can't half-assign a tuple or create a default tuple.  Tuples are immutable (you can't change the values once constructed), so thus you must provide all values at construction time. Another way to easily create tuples is to do it implicitly using the System.Tuple static class's Create() factory methods.  These methods (much like C++'s std::make_pair method) will infer the types from the method call so you don't have to type them in.  This can dramatically reduce the amount of typing required especially for complex tuples! 1: // this 4-tuple is typed Tuple<int, double, string, char> 2: var t4 = Tuple.Create(42, 3.1415927, "Love", 'X'); Notice how much easier it is to use the factory methods and infer the types?  This can cut down on typing quite a bit when constructing tuples.  The Create() factory method can construct from a 1-tuple (singleton) to an 8-tuple (octuple), which of course will be a octuple where the last item is a singleton as we described before in nested tuples. Accessing tuple members Accessing a tuple's members is simplicity itself… mostly.  The properties for accessing up to the first seven items are Item1, Item2, …, Item7.  If you have an octuple or beyond, the final property is Rest which will give you the nested tuple which you can then access in a similar matter.  Once again, keep in mind that these are read-only properties and cannot be changed. 1: // for septuples and below, use the Item properties 2: var t1 = Tuple.Create(42, 3.14); 3:  4: Console.WriteLine("First item is {0} and second is {1}", 5: t1.Item1, t1.Item2); 6:  7: // for octuples and above, use Rest to retrieve nested tuple 8: var t9 = new Tuple<int, int, int, int, int, int, int, 9: Tuple<int, int>>(1,2,3,4,5,6,7,Tuple.Create(8,9)); 10:  11: Console.WriteLine("The 8th item is {0}", t9.Rest.Item1); Tuples are IStructuralComparable and IStructuralEquatable Most of you know about IComparable and IEquatable, what you may not know is that there are two sister interfaces to these that were added in .NET 4.0 to help support tuples.  These IStructuralComparable and IStructuralEquatable make it easy to compare two tuples for equality and ordering.  This is invaluable for sorting, and makes it easy to use tuples as a compound-key to a dictionary (one of my favorite uses)! Why is this so important?  Remember when we said that some folks think tuples are too generic and you should define a custom class?  This is all well and good, but if you want to design a custom class that can automatically order itself based on its members and build a hash code for itself based on its members, it is no longer a trivial task!  Thankfully the tuple does this all for you through the explicit implementations of these interfaces. For equality, two tuples are equal if all elements are equal between the two tuples, that is if t1.Item1 == t2.Item1 and t1.Item2 == t2.Item2, and so on.  For ordering, it's a little more complex in that it compares the two tuples one at a time starting at Item1, and sees which one has a smaller Item1.  If one has a smaller Item1, it is the smaller tuple.  However if both Item1 are the same, it compares Item2 and so on. For example: 1: var t1 = Tuple.Create(1, 3.14, "Hi"); 2: var t2 = Tuple.Create(1, 3.14, "Hi"); 3: var t3 = Tuple.Create(2, 2.72, "Bye"); 4:  5: // true, t1 == t2 because all items are == 6: Console.WriteLine("t1 == t2 : " + t1.Equals(t2)); 7:  8: // false, t1 != t2 because at least one item different 9: Console.WriteLine("t2 == t2 : " + t2.Equals(t3)); The actual implementation of IComparable, IEquatable, IStructuralComparable, and IStructuralEquatable is explicit, so if you want to invoke the methods defined there you'll have to manually cast to the appropriate interface: 1: // true because t1.Item1 < t3.Item1, if had been same would check Item2 and so on 2: Console.WriteLine("t1 < t3 : " + (((IComparable)t1).CompareTo(t3) < 0)); So, as I mentioned, the fact that tuples are automatically equatable and comparable (provided the types you use define equality and comparability as needed) means that we can use tuples for compound keys in hashing and ordering containers like Dictionary and SortedList: 1: var tupleDict = new Dictionary<Tuple<int, double, string>, string>(); 2:  3: tupleDict.Add(t1, "First tuple"); 4: tupleDict.Add(t2, "Second tuple"); 5: tupleDict.Add(t3, "Third tuple"); Because IEquatable defines GetHashCode(), and Tuple's IStructuralEquatable implementation creates this hash code by combining the hash codes of the members, this makes using the tuple as a complex key quite easy!  For example, let's say you are creating account charts for a financial application, and you want to cache those charts in a Dictionary based on the account number and the number of days of chart data (for example, a 1 day chart, 1 week chart, etc): 1: // the account number (string) and number of days (int) are key to get cached chart 2: var chartCache = new Dictionary<Tuple<string, int>, IChart>(); Summary The System.Tuple, like any tool, is best used where it will achieve a greater benefit.  I wouldn't advise overusing them, on objects with a large scope or it can become difficult to maintain.  However, when used properly in a well defined scope they can make your code cleaner and easier to maintain by removing the need for extraneous POCOs and custom property hashing and ordering. They are especially useful in defining compound keys to IDictionary implementations and for returning multiple values from methods, or passing multiple values to a single object parameter. Tweet Technorati Tags: C#,.NET,Tuple,Little Wonders

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  • Use decorator and factory together to extend objects?

    - by TheClue
    I'm new to OOP and design pattern. I've a simple app that handles the generation of Tables, Columns (that belong to Table), Rows (that belong to Column) and Values (that belong to Rows). Each of these object can have a collection of Property, which is in turn defined as an enum. They are all interfaces: I used factories to get concrete instances of these products, depending on circumnstances. Now I'm facing the problem of extending these classes. Let's say I need another product called "SpecialTable" which in turn has some special properties or new methods like 'getSomethingSpecial' or an extended set of Property. The only way is to extend/specialize all my elements (ie. build a SpecialTableFactory, a SpecialTable interface and a SpecialTableImpl concrete)? What to do if, let's say, I plan to use standard methods like addRow(Column column, String name) that doesn't need to be specialized? I don't like the idea to inherit factories and interfaces, but since SpecialTable has more methods than Table i guess it cannot share the same factory. Am I wrong? Another question: if I need to define product properties at run time (a Table that is upgraded to SpecialTable at runtime), i guess i should use a decorator. Is it possible (and how) to combine both factory and decorator design? Is it better to use a State or Strategy pattern, instead?

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  • Oracle BI Server Modeling, Part 1- Designing a Query Factory

    - by bob.ertl(at)oracle.com
      Welcome to Oracle BI Development's BI Foundation blog, focused on helping you get the most value from your Oracle Business Intelligence Enterprise Edition (BI EE) platform deployments.  In my first series of posts, I plan to show developers the concepts and best practices for modeling in the Common Enterprise Information Model (CEIM), the semantic layer of Oracle BI EE.  In this segment, I will lay the groundwork for the modeling concepts.  First, I will cover the big picture of how the BI Server fits into the system, and how the CEIM controls the query processing. Oracle BI EE Query Cycle The purpose of the Oracle BI Server is to bridge the gap between the presentation services and the data sources.  There are typically a variety of data sources in a variety of technologies: relational, normalized transaction systems; relational star-schema data warehouses and marts; multidimensional analytic cubes and financial applications; flat files, Excel files, XML files, and so on. Business datasets can reside in a single type of source, or, most of the time, are spread across various types of sources. Presentation services users are generally business people who need to be able to query that set of sources without any knowledge of technologies, schemas, or how sources are organized in their company. They think of business analysis in terms of measures with specific calculations, hierarchical dimensions for breaking those measures down, and detailed reports of the business transactions themselves.  Most of them create queries without knowing it, by picking a dashboard page and some filters.  Others create their own analysis by selecting metrics and dimensional attributes, and possibly creating additional calculations. The BI Server bridges that gap from simple business terms to technical physical queries by exposing just the business focused measures and dimensional attributes that business people can use in their analyses and dashboards.   After they make their selections and start the analysis, the BI Server plans the best way to query the data sources, writes the optimized sequence of physical queries to those sources, post-processes the results, and presents them to the client as a single result set suitable for tables, pivots and charts. The CEIM is a model that controls the processing of the BI Server.  It provides the subject areas that presentation services exposes for business users to select simplified metrics and dimensional attributes for their analysis.  It models the mappings to the physical data access, the calculations and logical transformations, and the data access security rules.  The CEIM consists of metadata stored in the repository, authored by developers using the Administration Tool client.     Presentation services and other query clients create their queries in BI EE's SQL-92 language, called Logical SQL or LSQL.  The API simply uses ODBC or JDBC to pass the query to the BI Server.  Presentation services writes the LSQL query in terms of the simplified objects presented to the users.  The BI Server creates a query plan, and rewrites the LSQL into fully-detailed SQL or other languages suitable for querying the physical sources.  For example, the LSQL on the left below was rewritten into the physical SQL for an Oracle 11g database on the right. Logical SQL   Physical SQL SELECT "D0 Time"."T02 Per Name Month" saw_0, "D4 Product"."P01  Product" saw_1, "F2 Units"."2-01  Billed Qty  (Sum All)" saw_2 FROM "Sample Sales" ORDER BY saw_0, saw_1       WITH SAWITH0 AS ( select T986.Per_Name_Month as c1, T879.Prod_Dsc as c2,      sum(T835.Units) as c3, T879.Prod_Key as c4 from      Product T879 /* A05 Product */ ,      Time_Mth T986 /* A08 Time Mth */ ,      FactsRev T835 /* A11 Revenue (Billed Time Join) */ where ( T835.Prod_Key = T879.Prod_Key and T835.Bill_Mth = T986.Row_Wid) group by T879.Prod_Dsc, T879.Prod_Key, T986.Per_Name_Month ) select SAWITH0.c1 as c1, SAWITH0.c2 as c2, SAWITH0.c3 as c3 from SAWITH0 order by c1, c2   Probably everybody reading this blog can write SQL or MDX.  However, the trick in designing the CEIM is that you are modeling a query-generation factory.  Rather than hand-crafting individual queries, you model behavior and relationships, thus configuring the BI Server machinery to manufacture millions of different queries in response to random user requests.  This mass production requires a different mindset and approach than when you are designing individual SQL statements in tools such as Oracle SQL Developer, Oracle Hyperion Interactive Reporting (formerly Brio), or Oracle BI Publisher.   The Structure of the Common Enterprise Information Model (CEIM) The CEIM has a unique structure specifically for modeling the relationships and behaviors that fill the gap from logical user requests to physical data source queries and back to the result.  The model divides the functionality into three specialized layers, called Presentation, Business Model and Mapping, and Physical, as shown below. Presentation services clients can generally only see the presentation layer, and the objects in the presentation layer are normally the only ones used in the LSQL request.  When a request comes into the BI Server from presentation services or another client, the relationships and objects in the model allow the BI Server to select the appropriate data sources, create a query plan, and generate the physical queries.  That's the left to right flow in the diagram below.  When the results come back from the data source queries, the right to left relationships in the model show how to transform the results and perform any final calculations and functions that could not be pushed down to the databases.   Business Model Think of the business model as the heart of the CEIM you are designing.  This is where you define the analytic behavior seen by the users, and the superset library of metric and dimension objects available to the user community as a whole.  It also provides the baseline business-friendly names and user-readable dictionary.  For these reasons, it is often called the "logical" model--it is a virtual database schema that persists no data, but can be queried as if it is a database. The business model always has a dimensional shape (more on this in future posts), and its simple shape and terminology hides the complexity of the source data models. Besides hiding complexity and normalizing terminology, this layer adds most of the analytic value, as well.  This is where you define the rich, dimensional behavior of the metrics and complex business calculations, as well as the conformed dimensions and hierarchies.  It contributes to the ease of use for business users, since the dimensional metric definitions apply in any context of filters and drill-downs, and the conformed dimensions enable dashboard-wide filters and guided analysis links that bring context along from one page to the next.  The conformed dimensions also provide a key to hiding the complexity of many sources, including federation of different databases, behind the simple business model. Note that the expression language in this layer is LSQL, so that any expression can be rewritten into any data source's query language at run time.  This is important for federation, where a given logical object can map to several different physical objects in different databases.  It is also important to portability of the CEIM to different database brands, which is a key requirement for Oracle's BI Applications products. Your requirements process with your user community will mostly affect the business model.  This is where you will define most of the things they specifically ask for, such as metric definitions.  For this reason, many of the best-practice methodologies of our consulting partners start with the high-level definition of this layer. Physical Model The physical model connects the business model that meets your users' requirements to the reality of the data sources you have available. In the query factory analogy, think of the physical layer as the bill of materials for generating physical queries.  Every schema, table, column, join, cube, hierarchy, etc., that will appear in any physical query manufactured at run time must be modeled here at design time. Each physical data source will have its own physical model, or "database" object in the CEIM.  The shape of each physical model matches the shape of its physical source.  In other words, if the source is normalized relational, the physical model will mimic that normalized shape.  If it is a hypercube, the physical model will have a hypercube shape.  If it is a flat file, it will have a denormalized tabular shape. To aid in query optimization, the physical layer also tracks the specifics of the database brand and release.  This allows the BI Server to make the most of each physical source's distinct capabilities, writing queries in its syntax, and using its specific functions. This allows the BI Server to push processing work as deep as possible into the physical source, which minimizes data movement and takes full advantage of the database's own optimizer.  For most data sources, native APIs are used to further optimize performance and functionality. The value of having a distinct separation between the logical (business) and physical models is encapsulation of the physical characteristics.  This encapsulation is another enabler of packaged BI applications and federation.  It is also key to hiding the complex shapes and relationships in the physical sources from the end users.  Consider a routine drill-down in the business model: physically, it can require a drill-through where the first query is MDX to a multidimensional cube, followed by the drill-down query in SQL to a normalized relational database.  The only difference from the user's point of view is that the 2nd query added a more detailed dimension level column - everything else was the same. Mappings Within the Business Model and Mapping Layer, the mappings provide the binding from each logical column and join in the dimensional business model, to each of the objects that can provide its data in the physical layer.  When there is more than one option for a physical source, rules in the mappings are applied to the query context to determine which of the data sources should be hit, and how to combine their results if more than one is used.  These rules specify aggregate navigation, vertical partitioning (fragmentation), and horizontal partitioning, any of which can be federated across multiple, heterogeneous sources.  These mappings are usually the most sophisticated part of the CEIM. Presentation You might think of the presentation layer as a set of very simple relational-like views into the business model.  Over ODBC/JDBC, they present a relational catalog consisting of databases, tables and columns.  For business users, presentation services interprets these as subject areas, folders and columns, respectively.  (Note that in 10g, subject areas were called presentation catalogs in the CEIM.  In this blog, I will stick to 11g terminology.)  Generally speaking, presentation services and other clients can query only these objects (there are exceptions for certain clients such as BI Publisher and Essbase Studio). The purpose of the presentation layer is to specialize the business model for different categories of users.  Based on a user's role, they will be restricted to specific subject areas, tables and columns for security.  The breakdown of the model into multiple subject areas organizes the content for users, and subjects superfluous to a particular business role can be hidden from that set of users.  Customized names and descriptions can be used to override the business model names for a specific audience.  Variables in the object names can be used for localization. For these reasons, you are better off thinking of the tables in the presentation layer as folders than as strict relational tables.  The real semantics of tables and how they function is in the business model, and any grouping of columns can be included in any table in the presentation layer.  In 11g, an LSQL query can also span multiple presentation subject areas, as long as they map to the same business model. Other Model Objects There are some objects that apply to multiple layers.  These include security-related objects, such as application roles, users, data filters, and query limits (governors).  There are also variables you can use in parameters and expressions, and initialization blocks for loading their initial values on a static or user session basis.  Finally, there are Multi-User Development (MUD) projects for developers to check out units of work, and objects for the marketing feature used by our packaged customer relationship management (CRM) software.   The Query Factory At this point, you should have a grasp on the query factory concept.  When developing the CEIM model, you are configuring the BI Server to automatically manufacture millions of queries in response to random user requests. You do this by defining the analytic behavior in the business model, mapping that to the physical data sources, and exposing it through the presentation layer's role-based subject areas. While configuring mass production requires a different mindset than when you hand-craft individual SQL or MDX statements, it builds on the modeling and query concepts you already understand. The following posts in this series will walk through the CEIM modeling concepts and best practices in detail.  We will initially review dimensional concepts so you can understand the business model, and then present a pattern-based approach to learning the mappings from a variety of physical schema shapes and deployments to the dimensional model.  Along the way, we will also present the dimensional calculation template, and learn how to configure the many additivity patterns.

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  • Factory Girl sequence fails under autospec

    - by John
    I have this Factory: Factory.define :email_address do |e| e.sequence(:address) { |n| "factory_#{n}@example.com" } e.validated true end When I run my specs with rake spec, it works fine. When I run autospec, it fails right away, claiming that the email address is being used twice in two different objects (there is a validation which restricts this). Why is it behaving differently under autospec? Thanks, John

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  • Friday Fun: Factory Balls – Christmas Edition

    - by Asian Angel
    Your weekend is almost here, but until the work day is over we have another fun holiday game for you. This week your job is to correctly decorate/paint the ornaments that go on the Christmas tree. Simple you say? Maybe, but maybe not! Factory Balls – Christmas Edition The object of the game is to correctly decorate/paint each Christmas ornament exactly as shown in the “sample image” provided for each level. What starts off as simple will quickly have you working to figure out the correct combination or sequence to complete each ornament. Are you ready? The first level serves as a tutorial to help you become comfortable with how to decorate/paint the ornaments. To move an ornament to a paint bucket or cover part of it with one of the helper items simply drag the ornament towards that area. The ornament will automatically move back to its’ starting position when the action is complete. First, a nice coat of red paint followed by covering the middle area with a horizontal belt. Once the belt is on move the ornament to the bucket of yellow paint. Next, you will need to remove the belt, so move the ornament back to the belt’s original position. One ornament finished! As soon as you complete decorating/painting an ornament, you move on to the next level and will be shown the next “sample Image” in the upper right corner. Starting with a coat of orange paint sounds good… Pop the little serrated edge cap on top… Add some blue paint… Almost have it… Place the large serrated edge cap on top… Another dip in the orange paint… And the second ornament is finished. Level three looks a little bit tougher…just work out your pattern of helper items & colors and you will definitely get it! Have fun decorating/painting those ornaments! Note: Starting with level four you will need to start using a combination of two helper items combined at times to properly complete the ornaments. Play Factory Balls – Christmas Edition Latest Features How-To Geek ETC The Complete List of iPad Tips, Tricks, and Tutorials The 50 Best Registry Hacks that Make Windows Better The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor Exploring the Jungle Ruins Wallpaper Protect Your Privacy When Browsing with Chrome and Iron Browser Free Shipping Day is Friday, December 17, 2010 – National Free Shipping Day Find an Applicable Quote for Any Programming Situation Winter Theme for Windows 7 from Microsoft Score Free In-Flight Wi-Fi Courtesy of Google Chrome

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