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• Interconversion between decimal and any other base-n number system

  - by Webbisshh

  Hello there, I have written some general functions to convert between decimal and any other base-n number system(n<=36 for now) and vice-versa. Don't want to make things messy here so i have posted the code here. Could anybody suggest any better way for this? May be more effective and Rubyish? Thanks

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• Are there any purely functional Schemes or Lisps?

  - by nickname

  Over the past few months, I've put a lot of effort into learning (or attempting to learn) several functional programming languages. I really like math, so they have been very natural for me to use. Simply to be more specific, I have tried Common Lisp, Scheme, Haskell, OCaml, and (a little bit of) Erlang. I did not like the syntax of OCaml and do not have enough Erlang knowledge to make a judgment on it yet. Because of its consistent and beautiful (non-)syntax, I really like Scheme. However, I really do appreciate the stateless nature of purely functional programming languages such as Haskell. Haskell looks very interesting, but the amount of inconsistent and non-extendable syntax really bothered me. In the interest of preventing a Lisp vs Haskell flame war, just pretend that I can't use Haskell for some other reason. Therefore, my question is: Are there any purely functional Schemes (or Lisps in general)?

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• Where does C# and the .NET Framework fail?

  - by Nate Bross

  In my non-programming life, I always attempt to use the approprite tool for the job, and I feel that I do the same in my programming life, but I find that I am choosing C# and .NET for almost everything. I'm finding it hard to come up with (realistic business) needs that cannot be met by .NET and C#. Obviously embedded systems might require something less bloated than the .NET Micro Framework, but I'm really looking for line of business type situations where .NET is not the best tool. I'm primarly a C# and .NET guy since its what I'm the most comfertable in, but I know a fair amount of C++, php, VB, powershell, batch files, and Java, as well as being versed in the web technologes (javascript, html/css). But I'm open minded about it my skill set and I'm looking for cases where C# and .NET are not the right tool for the job. The bottom line here, is that I feel that I'm choosing C# and .NET simply because I am very comfertable with it, so I'm looking for cases where you have chosen something other than .NET, even though you are primarly a .NET developer.

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• Returning the same type the function was passed

  - by Ken Bloom

  I have the following code implementation of Breadth-First search. trait State{ def successors:Seq[State] def isSuccess:Boolean = false def admissableHeuristic:Double } def breadthFirstSearch(initial:State):Option[List[State]] = { val open= new scala.collection.mutable.Queue[List[State]] val closed = new scala.collection.mutable.HashSet[State] open.enqueue(initial::Nil) while (!open.isEmpty){ val path:List[State]=open.dequeue() if(path.head.isSuccess) return Some(path.reverse) closed += path.head for (x <- path.head.successors) if (!closed.contains(x)) open.enqueue(x::path) } return None } If I define a subtype of State for my particular problem class CannibalsState extends State { //... } What's the best way to make breadthFirstSearch return the same subtype as it was passed? Supposing I change this so that there are 3 different state classes for my particular problem and they share a common supertype: abstract class CannibalsState extends State { //... } class LeftSideOfRiver extends CannibalsState { //... } class InTransit extends CannibalsState { //... } class RightSideOfRiver extends CannibalsState { //... } How can I make the types work out so that breadthFirstSearch infers that the correct return type is CannibalsState when it's passed an instance of LeftSideOfRiver? Can this be done with an abstract type member, or must it be done with generics?

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• Finding Cities within 'X' Kilometers (or Miles)

  - by Mike Curry

  This may or may not be clear, leave me a comment if I am off base, or you need more information. Perhaps there is a solution out there already for what I want in PHP. I am looking for a function that will add or subtract a distance from a longitude OR latitude value. Reason: I have a database with all Latitudes and Longitudes in it and want to form a query to extract all cities within X kilometers (or miles). My query would look something like this... Select * From Cities Where (Longitude > X1 and Longitude < X2) And (Latitude > Y1 and Latitude < Y2) Where X1 = Longitude - (distance) Where X2 = Longitude + (distance) Where Y1 = Latitude - (distance) Where Y2 = Latitude + (distance) I am working in PHP, with a MySql Database. Open to any suggestions also! :)

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• Get coordinates in parent, but not in stage.

  - by Bart van Heukelom

  I know about Flash's localToGlobal and globalToLocal methods to transform coordinates from the local system to the global system, but is there a way to achieve the intermediate? To transform coordinates from an arbitrary system to any other arbitrary system? I have a clickable object inside a Sprite, and the Sprite is a child of the stage. I want to retrieve the clicked point in the Sprite.

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• Where/When do C# and the .NET Framework fail to be the right tool?

  - by Nate Bross

  In my non-programming life, I always attempt to use the appropriate tool for the job, and I feel that I do the same in my programming life, but I find that I am choosing C# and .NET for almost everything. I'm finding it hard to come up with (realistic business) needs that cannot be met by .NET and C#. Obviously embedded systems might require something less bloated than the .NET Micro Framework, but I'm really looking for line of business type situations where .NET is not the best tool. I'm primarly a C# and .NET guy since its what I'm the most comfertable in, but I know a fair amount of C++, php, VB, PowerShell, batch files, and Java, as well as being versed in the web technologes (JavaScript, HTML, and CSS). But I'm open minded about it my skill set and I'm looking for cases where C# and .NET are not the right tool for the job. I choose .NET and C# because I'm comfortable with it, but I'm looking for cases where it isn't appropriate.

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• Extending the .NET type system so the compiler enforces semantic meaning of primitive values in cert

  - by Drew Noakes

  I'm working with geometry a bit at the moment and am converting a lot between degrees and radians. Unfortunately, both of these are represented by double, so there's compile time warning/error if I try to pass a value in degrees where radians are expected. I believe F# has a compile-time solution for this (called units of measure.) I'd like to do something similar in C#. As another example, imagine a SQL library that accepts various query parameters as strings. It'd be good to have a way of enforcing that only clean strings were allowed to be passed in at runtime, and the only way to get a clean string was to pass through some SQL injection attack preventing logic. The obvious solution is to wrap the double/string/whatever in a new type to give it the type information the compiler needs. I'm curious if anyone has an alternative solution. If you do think wrapping is the only/best way, then please go into some of the downsides of the pattern (and any upsides I haven't mentioned too.) I'm especially concerned about the performance of abstracted primitive numeric types on my calculations at runtime.

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• Are there any languages that are dynamically typed but do not allow weak typing?

  - by Maulrus

  For example, adding a (previously undeclared) int and a string in pseudocode: x = 1; y = "2"; x + y = z; I've seen strongly typed languages that would not allow adding the two types, but those are also statically typed, so it's impossible to have a situation like above. On the other hand, I've seen weakly typed languages that allow the above and are statically typed. Are there any languages that are dynamically typed but are also strongly typed as well, so that the piece of code above would not be valid?

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• open source gossip-based membership protocol?

  - by Aaron

  I am looking for a library which I can plug into a distributed application which implements any gossip-based membership protocol. Such a library would allow me to send/receive membership lists, merge received membership lists, etc... Even better would be if the library implemented a protocol with performance O(logn) performance guarantees. Does anyone know of any open source library like this? It doesn't need to meet all of the aforementioned requirements; even something partially implemented would be helpful.

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• Is there any valid reason radians are used as the inputs to trig function in many modern languages?

  - by johnmortal

  Is there any pressing reason trig functions should use radian inputs in modern programming languages? As far as I know radians are typically ugly to deal with except in three cases: (1) You want to compute an arc length and you know the angle of the arc and (2) You need to do symbolic calculus with trig functions (3) certain infinite series expansion look prettier if the input is in radians. None of these scenarios seem like a worthy justification for every programming language I am familiar with using radian inputs for Sin, Cos, Tangent, etc... The third one sounds good because it might mean one gets faster computations using radians (very slightly faster- the cost of one additional floating point multiplication ) , but I am dubious even of that because most commonly the developer had to take an extra step to put the angle in radians in the first place. The other two are ridiculous justifications for all the added obscurity.

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• Sorting data by relevance, from multiple tables

  - by Oden

  Hey, How is it possible to sort data from multiple tables by relevance? My table structure is following: I have 3 tables in my database, one table contains the name of solar systems, the second for e.g. of planets. There is one more table, witch is a connection between solar systems and planets. If I want to get data of a planet, witch is in the Milky Way, i post this data to the server, and it gives me a multi-dimensional array witch contains: The Milky Way, with every planet in it Every planet, witch name contains the string Milky Way (maybe thats a bat example because i don't think that theres but one planet with this name, but the main concept is on file) But, i want to set the most relevant restaurants to the top of the array. (for the relevance i would check the description of the restaurants or something like that) So, how would you do that kind of data sorting?

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• perl and tcp/ip

  - by oren

  what is the most updated book on programming tcp/ip sockets with perl?

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• Opengl Coordinate System

  - by praveen

  Say I am using an Identity Matrix for my modelViewTransformation Matrix on an Open GL ES2.0 program. The Co-ordinate system in this case is the canonical opengl co-ordinate system which extends from (-1,-1,-1) to (1,,1,1). My question is, is this coordinate system right-handed or left-handed? A broader question: Is there a document with OpenGL which can list all the mathematical conventions followed by the API?

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• Learning Windows Services with C++

  - by Manav Sharma

  Hi, Can you suggest a good book for learning Windows Services programming using C++? Thanks,

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• Where/When does C# and the .NET Framework fail to be the right tool?

  - by Nate Bross

  In my non-programming life, I always attempt to use the approprite tool for the job, and I feel that I do the same in my programming life, but I find that I am choosing C# and .NET for almost everything. I'm finding it hard to come up with (realistic business) needs that cannot be met by .NET and C#. Obviously embedded systems might require something less bloated than the .NET Micro Framework, but I'm really looking for line of business type situations where .NET is not the best tool. I'm primarly a C# and .NET guy since its what I'm the most comfertable in, but I know a fair amount of C++, php, VB, powershell, batch files, and Java, as well as being versed in the web technologes (javascript, html/css). But I'm open minded about it my skill set and I'm looking for cases where C# and .NET are not the right tool for the job. The bottom line here, is that I feel that I'm choosing C# and .NET simply because I am very comfertable with it, so I'm looking for cases where you have chosen something other than .NET, even though you are primarly a .NET developer.

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• Ubuntu Linux main utilities

  - by Harry

  I've never used Ubuntu Linux before, but I am researching about the main system tools that are included, e.g. Windows has Disk Cleanup, Disk Defrag... but what does Ubuntu Linux have. I need to know what the main five utilities that are included on Ubuntu Linux and what do they do.

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• How to use a class's type as the type argument for an inherited collection property in C#

  - by Edelweiss Peimann

  I am trying to create a representation of various types of card that inherit from a generic card class and which all contain references to their owning decks. I tried re-declaring them, as suggested here, but it still won't convert to the specific card type. The code I currently have is as such: public class Deck<T> : List<T> where T : Card { void Shuffle() { throw new NotImplementedException("Shuffle not yet implemented."); } } public class Card { public Deck<Card> OwningDeck { get; set; } } public class FooCard : Card { public Deck<FooCard> OwningDeck { get { return (Deck<FooCard>)base.OwningDeck; } set { OwningDeck = value; } } } The compile-time error I am getting: Error 2 Cannot convert type 'Game.Cards.Deck' to 'Game.Cards.Deck' And a warning suggesting I use a new operator to specify that the hiding is intentional. Would doing so be a violation of convention? Is there a better way? My question to stackoverflow is this: Can what I am trying to do be done elegantly in the .NET type system? If so, can some examples be provided?

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• Bash PATH: How long is too long?

  - by ajwood

  Hi, I'm currently designing a software quarantine pattern to use on Ubuntu. I'm not sure how standard "quarantine" is in this context, so here is what I hope to accomplish... Inside a particular quarantine is all of the stuff one needs to run an application (bin, share, lib, etc.). Ideally, the quarantine has no leaks, which means it's not relying on any code outside of itself on the system. A quarantine can be defined as a set of executables (and some environment settings needed to make them run). I think it will be beneficial to separate the built packages enough such that upgrading to a newer version of the quarantine won't require rebuilding the whole thing. I'll be able to update just a few packages, and then the new quarantine can use some of old parts and some of the new parts. One issue I'm wondering about is the environment variables I'll be setting up to use a particular quarantines. Is there a hard limit on how big PATH can be? (either in number of characters, or in the number of directories it contains) Might a path be so long that it affects performance? Thanks very much, Andrew p.s. Any other wisdom that might help my design would be greatly appreciated :)

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• Get countries within range of LAT/LONG coordinates

  - by ptrn

  Trouble! I'm looking for a way to find the countries within a given range of LAT/LONG coordinates. E.g.: When viewing a place in Africa in Google Maps, I get out which countries that are in my current view. This is a bit ambitious, and I think the main problem will be dealing with accuracy of the needed polygons. The accuracy of these don't need to be all that great, the borders can probably be tens of miles off, or even more. This will be needed for the entire world.

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• What are the flavor-of-the-month technologies that have now become obscure?

  - by Andreas Grech

  For this question, I am looking for programming languages, technologies and standards that where considered as a flavour-of-the-month in their prominent time but have since been forgotten in today's programming world. Also, with what have they been replaced? I am relatively new to the software development industry compared to most of the people here (with just only 5 years of experience), and from this question I am looking to learn about some of the now-obscure technologies that have been around during your time. Just for clarification, what I mean by flavour-of-the-month is technologies that had been extensively in their time but today have become obscure and forgotten; maybe replaced by other better ones

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• iphone singleton object synchronization

  - by user127091

  I'm working on an iphone app but this is probably a general question. I have a singleton Model class and there would be scenarios where multiple NSOperations (threads) would exist and work with the singleton object. If they all call the same method in this object, do i need to have some locking mechanism? Or can this method be executed only one at a time? I do not have a computer science background but my guess is that all threads would have their CALL to the same address (this method). Also can you please suggest a good beginner programming book that discusses general programming concepts. I don't have the brains for Knuth kinda books.

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• whats a sure shot way to make sure objects appear correctly positioned on stage

  - by dubbeat

  Hi, I've being having a lot of trouble recently getting objects (UIComponents containing movieclips) to appear correctly in the right positions. For example, my current dilema is I have a container that is 3 layers deep. outer layer inner layer display layer This hiearachy was built in CS4 as a movieclip. In the display layer in CS4 I figured out where I want to place 16 different "box" movieclips. I dont want to create these boxes maunually at design time, instead I want to add them at run time. So I know what container I want to add my boxes to. I know what positions they "would" be at in CS4 environment. Whats the best way to add them in the correct locations with code? The "box" I'm trying to add in a movieclip held inside of a UIComponent. Is there a "rule of thumb" to do this type of thing? I'm sure I'm going to encounter this problem again and again and I'd like to just blow the problem out of the water once and for all with the "right way" to do this.

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• Count the number of ways in which a number 'A' can be broken into a sum of 'B' numbers such that all numbers are co-prime to 'C'

  - by rajneesh2k10

  I came across the solution of a problem which involve dynamic-programming approach, solved using a three dimensional matrix. Link to actual problem is: http://community.topcoder.com/stat?c=problem_statement&pm=12189&rd=15177 Solution to this problem is here under MuddyRoad2: http://apps.topcoder.com/wiki/display/tc/SRM+555 In the last paragraph of explanation, author describes a dynamic programming approach to count the number of ways in which a number 'A' can be broken into a sum of 'B' numbers (not necessarily different), such that every number is co-prime to 3 and the order in which these numbers appear does matter. I am not able to grasp that approach. Can anyone help me understand how DP is acting here. I can't understand what is a state here and how it is derived from the previous state.

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• What is the most efficient functional version of the following imperative code?

  - by justin.r.s.

  I'm learning Scala and I want to know the best way of expressing this imperative pattern using Scala's functional programming capabilities. def f(l: List[Int]): Boolean = { for (e <- l) { if (test(e)) return true } } return false } The best I can come up with is along the lines of: l map { e => test(e) } contains true But this is less efficient since it calls test() on each element, whereas the imperative version stops on the first element that satisfies test(). Is there a more idiomatic functional programming technique I can use to the same effect? The imperative version seems awkward in Scala.

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