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  • Are web-safe colors still relevant?

    - by Gavin Miller
    Since the vast majority of monitors are 16-bit color or more, including mobile devices, does it make sense to even consider web-safe colors when choosing color schemes? Or is it something that ought to be relegated to history as a piece of trivia? For those of you that don't know what web-safe colors are: Another set of 216 color values is commonly considered to be the "web-safe" color palette, developed at a time when many computer displays were only capable of displaying 256 colors. A set of colors was needed that could be shown without dithering on 256-color displays; the number 216 was chosen partly because computer operating systems customarily reserved sixteen to twenty colors for their own use; it was also selected because it allows exactly six shades each of red, green, and blue (6 × 6 × 6 = 216). The list of colors is often presented as if it has special properties that render them immune to dithering. In fact, on 256-color displays applications can set a palette of any selection of colors that they choose, dithering the rest. These colors were chosen specifically because they matched the palettes selected by the then leading browser applications. [Wikipedia]

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  • Storing varchar(max) & varbinary(max) together - Problem?

    - by Tony Basallo
    I have an app that will have entries of both varchar(max) and varbinary(max) data types. I was considering putting these both in a separate table, together, even if only one of the two will be used at any given time. The question is whether storing them together has any impact on performance. Considering that they are stored in the heap, I'm thinking that having them together will not be a problem. However, the varchar(max) column will be probably have the text in row table option set. I couldn't find any performance testing or profiling while "googling bing," probably too specific a question? The SQL Server 2008 table looks like this: Id ParentId Version VersionDate StringContent - varchar(max) BinaryContent - varbinary(max) The app will decide which of the two columns to select for when the data is queried. The string column will much used much more frequently than the binary column - will this have any impact on performance?

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  • should this database table be normalized?

    - by oo
    i have taken over a database that stores fitness information and we were having a debate about a certain table and whether it should stay as one table or get broken up into three tables. Today, there is one table called: workouts that has the following fields id, exercise_id, reps, weight, date, person_id So if i did 2 sets of 3 different exercises on one day, i would have 6 records in that table for that day. for example: id, exercise_id, reps, weight, date, person_id 1, 1, 10, 100, 1/1/2010, 10 2, 1, 10, 100, 1/1/2010, 10 3, 1, 10, 100, 1/1/2010, 10 4, 2, 10, 100, 1/1/2010, 10 5, 2, 10, 100, 1/1/2010, 10 6, 2, 10, 100, 1/1/2010, 10 So the question is, given that there is some redundant data (date, personid, exercise_id) in multiple records, should this be normalized to three tables WorkoutSummary: - id - date - person_id WorkoutExercise: - id - workout_id (foreign key into WorkoutSummary) - exercise_id WorkoutSets: - id - workout_exercise_id (foreign key into WorkoutExercise) - reps - weight I would guess the downside is that the queries would be slower after this refactoring as now we would need to join 3 tables to do the same query that had no joins before. The benefit of the refactoring allows up in the future to add new fields at the workout summary level or the exercise level with out adding in more duplication. any feedback on this debate?

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  • DDD and Client/Server apps

    - by Christophe Herreman
    I was wondering if any of you had successfully implemented DDD in a Client/Server app and would like to share some experiences. We are currently working on a smart client in Flex and a backend in Java. On the server we have a service layer exposed to the client that offers CRUD operations amongst some other service methods. I understand that in DDD these services should be repositories and services should be used to handle use cases that do not fit inside a repository. Right now, we mimic these services on the client behind an interface and inject implementations (Webservices, RMI, etc) via an IoC container. So some questions arise: should the server expose repositories to the client or do we need to have some sort of a facade (that is able to handle security for instance) should the client implement repositories (and DDD in general?) knowing that in the client, most of the logic is view related and real business logic lives on the server. All communication with the server happens asynchronously and we have a single threaded programming model on the client. how about mapping client to server objects and vice versa? We tried DTO's but reverted back to exposing the state of our objects and mapping directly to them. I know this is considered bad practice, but it saves us an incredible amount of time) In general I think a new generation of applications is coming with the growth of Flex, Silverlight, JavaFX and I'm curious how DDD fits into this.

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  • Execute remote Lua Script

    - by Bruno Lee
    Hi, I want to make an application that executes a remote script. The user can create a script (probabily a LUA script) then stores it in the server. Then he can uses an API for execute the script. I was thinking that API could be a webservice. So my questions are: I need high performance to execute the script. So my first choice was LUA script. Someone has another sugestion? Cause I need high perfomance, I was thinking if the webservice is the best solution. Maybe I could create a TCP/IP Windows Service that hold the users request. It is important to say that I will have many user executing scripts at the same time. So I will have a concurrency problem. My scripts will query in a database. I will use Tokyo Cabinet or Tokio Tyrant. I think Tokio Tyrant is the only solution cause I will have many requests. For perfomance, Do I need to make a connection pooling? Is there anyway to share variables between webservices requests? To make the webservice or the Windows service i was thinking to use C++. Can someone help with these questions? thanks

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  • Best code structure for arcade games

    - by user280454
    Hi, I've developed a few arcade games so far and have the following structure in almost all of them: I have 1 file which contains a class called kernel with the following functions: init() welcome_screen() menu_screen() help_Screen() play_game() end_screen() And another file, called Game, which basically calls all these functions and controls the flow of the game. Also, I have classes for different characters, whenever required. Is this a good code structure, or should I try having different files(classes) for different functions like welcome screen, playing, help screen, etc? As in, instead of including all the code for these things in 1 file, should I be having different classes for each one of them? The only problem I think it might cause is that I would need certain variables like score, characters, etc which are common to all of them, that's why I have all these functions in a Kernel class so that all these functions can use these variables.

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  • SO what RDF database do i use?

    - by keisimone
    Hi, i have a similar issue as espoused in http://stackoverflow.com/questions/695752/product-table-many-kinds-of-product-each-product-has-many-parameters i am convinced to use RDF now. but i already have a database in mysql and the code is in php. 1) So what RDF database should I use? 2) do i combine the approach? meaning i have a class table inheritance in the mysql database and just the weird product attributes in the RDF? I dont think i should move everything to a RDF database since it is only just products and the wide array of possible attributes and value that is giving me the problem. 3) what php resources, articles should i look at that will help me better in the creation of this? 4) thank you.

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  • Pagination For SMS in Android specifically

    - by Priyank
    Hi. I had a pagination related question posted earlier. Here I went through the posted answers and suggested choices and I realized that to implement pagination in an application I could still write db level queries and ensure that I could implement pagination, even if in a crude form. However I have few follow up questions now: I am trying to show SMS from a content provider. Suppose I don't want to use content provider; can I access SMS table in database through my application. Aoes android's security framework allow that? How do people generally handle pagination problems in android, related to content that they are not storing but instead are fetching through content providers. (Android's own or custom) Isn't this a bigger problem. I am surprised to find so little text online about it.

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  • Converting old WCF service to RIA one

    - by Artur
    Hi there, Currently I have a service that looks like: Some app <-- WCF Service <-- Business Logic <-- Entity Framework Model <-- SQL Database One of "some app" would be Silverlight, but there as well will be lots of other clients (mainly mobile devices). To me the greatest benefit of having RIA services is possibility of making ordinary (not asynchronous) calls from Silverlight. I wondered if there is an easy way of converting what I have so far to be a RIA service? I as well wonder if there is a point of doing so if I plan to use the same service for multiple platforms/clients? Any help/links would be greatly appreciated.

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  • Accessing the Private Constructor

    - by harigm
    I am java developer, went for an interview. I have been asked a question about the Private constructor 1) Can I access a Private Constructor of a Class and Instantiate the class. I was thinking and gave the answer directly--- "NO" But its wrong, can any one help Why NO? and How we can achieve this

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  • Questions and considerations to ask client for designing a database

    - by Julia
    Hi guys! so as title says, I would like to hear your advices what are the most important questions to consider and ask end-users before designing database for their application. We are to make database-oriented app, with special attenion to pay on db security (access control, encryption, integrity, backups)... Database will also keep some personal information about people, which is considered sensitive by law regulations, so security must be good. I worked on school projects with databases, but this is first time working "in real world", where this db security has real implications. So I found some advices and questions to ask on internet, but here I always get best ones. All help appreciated! Thank you!

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  • DRY programming dilemma

    - by fayer
    the situation is like this: im creating a Logger class that can write to a file but the write_to_file() function is in a helper class as a static function. i could call that function but then the Log class would be dependent to the helper class. isn't dependency bad? but if i can let it use a helper function then what is the point of having helper functions? what should one prioritize here: using helper functions and have to include this helper class everywhere (but the other 99 methods wont be useful) or just copy and paste into the Log class (but then if i have done this 100 times and then make a change i have to change in 100 places). share your thoughts and experience!

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  • Relational vs. Dimensional Databases, what's the difference?

    - by grautur
    I'm trying to learn about OLAP and data warehousing, and I'm confused about the difference between relational and dimensional modeling. Is dimensional modeling basically relational modeling, but allowing for redundant/un-normalized data? For example, let's say I have historical sales data on (product, city, # sales). I understand that the following would be a relational point-of-view: Product | City | # Sales Apples, San Francisco, 400 Apples, Boston, 700 Apples, Seattle, 600 Oranges, San Francisco, 550 Oranges, Boston, 500 Oranges, Seattle, 600 While the following is a more dimensional point-of-view: Product | San Francisco | Boston | Seattle Apples, 400, 700, 600 Oranges, 550, 500, 600 But it seems like both points of view would nonetheless be implemented in an identical star schema: Fact table: Product ID, Region ID, # Sales Product dimension: Product ID, Product Name City dimension: City ID, City Name And it's not until you start adding some additional details to each dimension that the differences start popping up. For instance, if you wanted to track regions as well, a relational database would tend to have a separate region table, in order to keep everything normalized: City dimension: City ID, City Name, Region ID Region dimension: Region ID, Region Name, Region Manager, # Regional Stores While a dimensional database would allow for denormalization to keep the region data inside the city dimension, in order to make it easier to slice the data: City dimension: City ID, City Name, Region Name, Region Manager, # Regional Stores Is this correct?

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  • How to avoid using this in a contructor

    - by Paralife
    I have this situation: interface MessageListener { void onMessageReceipt(Message message); } class MessageReceiver { MessageListener listener; public MessageReceiver(MessageListener listener, other arguments...) { this.listener = listener; } loop() { Message message = nextMessage(); listener.onMessageReceipt(message); } } and I want to avoid the following pattern: (Using the this in the Client constructor) class Client implements MessageListener { MessageReceiver receiver; MessageSender sender; public Client(...) { receiver = new MessageReceiver(this, other arguments...); sender = new Sender(...); } . . . @Override public void onMessageReceipt(Message message) { if(Message.isGood()) sender.send("Congrtulations"); else sender.send("Boooooooo"); } } The reason why i need the above functionality is because i want to call the sender inside the onMessageReceipt() function, for example to send a reply. But I dont want to pass the sender into a listener, so the only way I can think of is containing the sender in a class that implements the listener, hence the above resulting Client implementation. Is there a way to achive this without the use of 'this' in the constructor? It feels bizare and i dont like it, since i am passing myself to an object(MessageReceiver) before I am fully constructed. On the other hand, the MessageReceiver is not passed from outside, it is constructed inside, but does this 'purifies' the bizarre pattern? I am seeking for an alternative or an assurance of some kind that this is safe, or situations on which it might backfire on me.

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  • good way to implement NotSpecification: isSpecialCaseOf?

    - by koen
    I'm implementing the specification pattern. The NotSpecification seems simple at first: NotSpecification.IsSpecialCaseOf(otherSpecification) return !this.specification.isSpecialCaseOf(otherSpecification) But it doesn't work for all Specifications: Not(LesserThan(5)).IsSpecialCaseOf(GreaterThan(4)) This should be true. So far I think that the only way to accomplish the isSpecialCaseOf the NotSpecification is to implement the remainderUnsatisfiedBy (partial subsumption in the paper on the specification pattern). But maybe I am missing something more simple or a logical insight that makes this unnecessary. Question: Is there another way of implementing this by not using remainderUnsatisfiedBy?

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  • ASP-style tags for Perl web development?

    - by Alex R
    I feel like I'm traveling 10 years back in time by asking this, but... Are there any modules, patches, or any "new" version of Perl (released in the last 10 years) to enable writing web-oriented Perl scripts using ASP-style tags? e.g. from ASP/JSP some html <% some code %> more HTML e.g. from PHP some html <? some code ?> more HTML Please don't worry about "why" I'm asking this... It's related to programming language research.

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  • Why "alt" attribute for <img> tag has been considered mandatory by the HTML validator .. ?

    - by infant programmer
    Is there any logical or technical reason (with the W3C validation) for making alt as required attribute .. This is my actual problem:though my page is perfect enough with respect to W3C validation rules .. Only error I am getting is line XX column YY - Error: required attribute "ALT" not specified I know the significance of "alt" attribute and I have omitted that where it is unnecessary .. (to be more elaborate .. I have added the image to increase the beauty of my page and I don't want alt attribute to show irrelevant message to the viewer) getting rid of the error is secondary .. rather I am curious to know whether is it a flaw with validation rules .. ?? I thank stackOverflow and all the members who responded me .. I got my doubt clarified .. :-)

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  • Optimize mysql table ?

    - by fabien-barbier
    Here is my actual table schema (I'm using Mysql) : Table experiment : code(int) sample_1_id sample_2_id ... until ... sample_12_id rna_1_id rna_2_id ... until ... rna_12_id experiment_start How can I optimize both part : sample_n_id and rna_n_id (all are bigint(20) and allow null=true) ? About values : we can have : ex : sample_1_id = 2 , Sample_2_id = 5 , ... Note : values can be updated. Ideas ? Thanks.

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  • Adding functionality to any TextReader

    - by strager
    I have a Location class which represents a location somewhere in a stream. (The class isn't coupled to any specific stream.) The location information will be used to match tokens to location in the input in my parser, to allow for nicer error reporting to the user. I want to add location tracking to a TextReader instance. This way, while reading tokens, I can grab the location (which is updated by the TextReader as data is read) and give it to the token during the tokenization process. I am looking for a good approach on accomplishing this goal. I have come up with several designs. Manual location tracking Every time I need to read from the TextReader, I call AdvanceString on the Location object of the tokenizer with the data read. Advantages Very simple. No class bloat. No need to rewrite the TextReader methods. Disadvantages Couples location tracking logic to tokenization process. Easy to forget to track something (though unit testing helps with this). Bloats existing code. Plain TextReader wrapper Create a LocatedTextReaderWrapper class which surrounds each method call, tracking a Location property. Example: public class LocatedTextReaderWrapper : TextReader { private TextReader source; public Location Location { get; set; } public LocatedTextReaderWrapper(TextReader source) : this(source, new Location()) { } public LocatedTextReaderWrapper(TextReader source, Location location) { this.Location = location; this.source = source; } public override int Read(char[] buffer, int index, int count) { int ret = this.source.Read(buffer, index, count); if(ret >= 0) { this.location.AdvanceString(string.Concat(buffer.Skip(index).Take(count))); } return ret; } // etc. } Advantages Tokenization doesn't know about Location tracking. Disadvantages User needs to create and dispose a LocatedTextReaderWrapper instance, in addition to their TextReader instance. Doesn't allow different types of tracking or different location trackers to be added without layers of wrappers. Event-based TextReader wrapper Like LocatedTextReaderWrapper, but decouples it from the Location object raising an event whenever data is read. Advantages Can be reused for other types of tracking. Tokenization doesn't know about Location tracking or other tracking. Can have multiple, independent Location objects (or other methods of tracking) tracking at once. Disadvantages Requires boilerplate code to enable location tracking. User needs to create and dispose the wrapper instance, in addition to their TextReader instance. Aspect-orientated approach Use AOP to perform like the event-based wrapper approach. Advantages Can be reused for other types of tracking. Tokenization doesn't know about Location tracking or other tracking. No need to rewrite the TextReader methods. Disadvantages Requires external dependencies, which I want to avoid. I am looking for the best approach in my situation. I would like to: Not bloat the tokenizer methods with location tracking. Not require heavy initialization in user code. Not have any/much boilerplate/duplicated code. (Perhaps) not couple the TextReader with the Location class. Any insight into this problem and possible solutions or adjustments are welcome. Thanks! (For those who want a specific question: What is the best way to wrap the functionality of a TextReader?) I have implemented the "Plain TextReader wrapper" and "Event-based TextReader wrapper" approaches and am displeased with both, for reasons mentioned in their disadvantages.

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  • Are there any applications written in the Io programming language? (Or, distributing Io applications

    - by Rayne
    I've recently become interested in prototype-based OOP, and I've been playing with Io and Ioke. Distributing an application with Ioke is simple. It's on the JVM. Need I say more? However, I'm absolutely stumped as to how one would distribute an Io application, especially on Windows. It's not like you can have end-users compile Io to run your application. I was actually shocked the Io has gone for 8 years without forming some sort of standards for things like distribution. Ruby has gems, Java has jars, and so on. The worse thing about it is, I can't find a single application written in Io to maybe steal ideas on distribution from. Maybe I suck at google searching (Io is a horrible search name, by the way ;P). Is there any sort of canonical way to distribute Io applications? Are there even any Io applications in existence, or am I just missing the point? I'm not sure if this should be community wiki or not. If you think it should, comment and let me know.

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  • Implementation of a general-purpose object structure (property bag)

    - by Thomas Wanner
    We need to implement some general-purpose object structure, much like an object in dynamic languages, that would give us a possibility of creating the whole object graph on-the-fly. This class has to be serializable and somehow user friendly. So far we have made some experiments with class derived from Dictionary<string, object> using the dot notation path to store properties and collections in the object tree. We have also find an article that implements something similar, but it doesn't seem to fit completely into our picture either. Do you know about some good implementations / libraries that deal with a similar problem or do you have any (non-trivial) ideas that could help us with our own implementation ? Also, I probably have to say that we are using .NET 3.5, so we can't take advantage of the new features in .NET 4.0 like dynamic type etc. (as far as I know it's also not possible to use any subset of it in .NET 3.5 solution).

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  • Confused about this factory, as it doesn't look like an Abstract Factory nor Factory Method

    - by Pin
    I'm looking into Guice and I've been reading its documentation recently. Reading the motivation section I don't understand the factories part, why they name it that way. To me that factory is just a wrapper for the implementing class they want it to return after calling getInstance(). public class CreditCardProcessorFactory { private static CreditCardProcessor instance; public static void setInstance(CreditCardProcessor creditCardProcessor) { instance = creditCardProcessor; } public static CreditCardProcessor getInstance() { if (instance == null) { throw new IllegalStateException("CreditCardProcessorFactory not initialized. " + "Did you forget to call CreditCardProcessor.setInstance() ?"); } return instance; } } Why do they call it factory as well if it is neither an abstract factory nor a factory method? Or am I missing something? Thanks.

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  • Allocation algorithm help, using Python.

    - by Az
    Hi there, I've been working on this general allocation algorithm for students. The pseudocode for it (a Python implementation) is: for a student in a dictionary of students: for student's preference in a set of preferences (ordered from 1 to 10): let temp_project be the first preferred project check if temp_project is available if so, allocate it to them and make the project UNavailable to others Quite simply this will try to allocate projects by starting from their most preferred. The way it works, out of a set of say 100 projects, you list 10 you would want to do. So the 10th project wouldn't be the "least preferred overall" but rather the least preferred in their chosen set, which isn't so bad. Obviously if it can't allocate a project, a student just reverts to the base case which is an allocation of None, with a rank of 11. What I'm doing is calculating the allocation "quality" based on a weighted sum of the ranks. So the lower the numbers (i.e. more highly preferred projects), the better the allocation quality (i.e. more students have highly preferred projects). That's basically what I've currently got. Simple and it works. Now I'm working on this algorithm that tries to minimise the allocation weight locally (this pseudocode is a bit messy, sorry). The only reason this will probably work is because my "search space" as it is, isn't particularly large (just a very general, anecdotal observation, mind you). Since the project is only specific to my Department, we have their own limits imposed. So the number of students can't exceed 100 and the number of preferences won't exceed 10. for student in a dictionary/list/whatever of students: where i = 0 take the (i)st student, (i+1)nd student for their ranks: allocate the projects and set local_weighting to be sum(student_i.alloc_proj_rank, student_i+1.alloc_proj_rank) these are the cases: if local_weighting is 2 (i.e. both ranks are 1): then i += 1 and and continue above if local weighting is = N>2 (i.e. one or more ranks are greater than 1): let temp_local_weighting be N: pick student with lowest rank and then move him to his next rank and pick the other student and reallocate his project after this if temp_local_weighting is < N: then allocate those projects to the students move student with lowest rank to the next rank and reallocate other if temp_local_weighting < previous_temp_allocation: let these be the new allocated projects try moving for the lowest rank and reallocate other else: if this weighting => previous_weighting let these be the allocated projects i += 1 and move on for the rest of the students So, questions: This is sort of a modification of simulated annealing, but any sort of comments on this would be appreciated. How would I keep track of which student is (i) and which student is (i+1) If my overall list of students is 100, then the thing would mess up on (i+1) = 101 since there is none. How can I circumvent that? Any immediate flaws that can be spotted? Extra info: My students dictionary is designed as such: students[student_id] = Student(student_id, student_name, alloc_proj, alloc_proj_rank, preferences) where preferences is in the form of a dictionary such that preferences[rank] = {project_id}

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  • C# Setting Properties using Index

    - by Guazz
    I have a business class that contains many properties for various stock-exchange price types. This is a sample of the class: public class Prices { public decimal Today {get; set} public decimal OneDay {get; set} public decimal SixDay {get; set} public decimal TenDay {get; set} public decimal TwelveDay {get; set} public decimal OneDayAdjusted {get; set;} public decimal SixDayAdjusted {get; set;} public decimal TenDayAdjusted {get; set;} public decimal OneHundredDayAdjusted {get; set;} } I have a legacy system that supplies the prices using string ids to identify the price type. E.g. Today = "0D" OneDay = "1D" SixDay = "6D" //..., etc. Firstly, I load all the values to an IDictionary() collection so we have: [KEY] VALUE [0D] = 1.23456 [1D] = 1.23456 [6D] = 1.23456 ...., etc. Secondly, I set the properties of the Prices class using a method that takes the above collection as a parameter like so: SetPricesValues(IDictionary<string, decimal> pricesDictionary) { // TODAY'S PRICE string TODAY = "D0"; if (true == pricesDictionary.ContainsKey(TODAY)) { this.Today = pricesDictionary[TODAY]; } // OneDay PRICE string ONE_DAY = "D1"; if (true == pricesDictionary.ContainsKey(ONE_DAY)) { this.OneDay = pricesDictionary[ONE_DAY]; } //..., ..., etc., for each other property } Is there a more elegant technique to set a large amount of properties? Thanks, j

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