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• What programming languages do you consider indispensable in your experience?

  - by Federico Ramponi

  Each programming language comes with its concepts, best practices, libraries, tools, community, in one word: culture. Learning more than one programming language will make you a better programmer, for the more concepts you learn, the faster you will feel comfortable when the next language or technology will come. Mine, so far, are C, some C++, and Python, and many times I read that it would be worth learning LISP, for "the profound enlightenment experience you will have when you finally get it" (quoting Eric Raymond). My questions are: Which is the next one you would consider a good investment to learn? Of the many programming languages you have learnt and worked with, which ones do you consider to be an essential part of one's CS culture, and why? EDIT. Further question: is there any language you would sincerely advise to avoid as a waste of time? (The famous, and questionable, slatings in this letter from Dijkstra come to my mind.)

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• In a C++ template, is it allowed to return an object with spesific type parameters?

  - by nieldw

  When I've got a template with certain type parameters, is it allowed for a function to return an object of this same template, but with different types? In other words, is the following allowed? template<class edgeDecor, class vertexDecor, bool dir> Graph<edgeDecor,int,dir> Graph<edgeDecor,vertexDecor,dir>::Dijkstra(vertex s, bool print = false) const { /* Construct new Graph with apropriate decorators */ Graph<edgeDecor,int,dir> span = new Graph<edgeDecor,int,dir>(); /* ... */ return span; }; If this is not allowed, how can I accomplish the same kind of thing?

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• Global variables in hadoop.

  - by Deepak Konidena

  Hi, My program follows a iterative map/reduce approach. And it needs to stop if certain conditions are met. Is there anyway i can set a global variable that can be distributed across all map/reduce tasks and check if the global variable reaches the condition for completion. Something like this. While(Condition != true){ Configuration conf = getConf(); Job job = new Job(conf, "Dijkstra Graph Search"); job.setJarByClass(GraphSearch.class); job.setMapperClass(DijkstraMap.class); job.setReducerClass(DijkstraReduce.class); job.setOutputKeyClass(IntWritable.class); job.setOutputValueClass(Text.class); } Where condition is a global variable that is modified during/after each map/reduce execution.

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• In a C++ template, is it allowed to return an object with specific type parameters?

  - by nieldw

  When I've got a template with certain type parameters, is it allowed for a function to return an object of this same template, but with different types? In other words, is the following allowed? template<class edgeDecor, class vertexDecor, bool dir> Graph<edgeDecor,int,dir> Graph<edgeDecor,vertexDecor,dir>::Dijkstra(vertex s, bool print = false) const { /* Construct new Graph with apropriate decorators */ Graph<edgeDecor,int,dir> span = new Graph<edgeDecor,int,dir>(); /* ... */ return span; }; If this is not allowed, how can I accomplish the same kind of thing?

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• ArchBeat Link-o-Rama for 2012-06-14

  - by Bob Rhubart

  Duke's Choice Award Nominations Close Friday! | The Java Source The Duke's Choice Awards celebrate extreme innovation in the world of Java technology. Nominate an individual, a group or company who show the best in Java innovation. Nominate at Java.net/dukeschoice. Nominations are open until this Friday, June 15. Whole Lotta Virtualization Goin' On | Rick Ramsey The OTN Garage's Rick Ramsey shares a list of recent Virtualization articles available on OTN, along with a link to a video by The Killer, Mr Jerry Lee Lewis. A Pragmatic Path to Navigating your Infrastructure to the Cloud | The WebLogic Server Blog Ruma Sanyal offers an overview of a recent Oracle webcast featuring Gartner VP and Distinguished Analyst Andy Butler and Vice President and Gartner Fellow Massimo Pezzini. Migrating C/C++ embedded SQL code | Tom Laszewski Cloud migration expert Tom Laszewski explains the how-to in 5 easy steps. Aetna Dumps Its Siloed Enterprise Architecture for SOA | CIO.com CIO writer Stephanie Overby tells the story of how one major health insurance provider put the "Enterprise" back in Enterprise Architecture. (H/T to Joe McKendrick for this story.) Downloading specific video renditions in WebCenter Content | Kyle Hatlestad How-to from Oracle WebCenter & ADF A-Team blogger Kyle Hatlestad. Eclipse DemoCamp - June 2012 - Redwood Shores, CA Location: Oracle HQ - 10 Twin Dolphin Drive, Redwood Shores, CA (Map) Date and Time: Wednesday, June 13, 2012. From 6pm - 9pm Agenda: The evolution of Java persistence, Doug Clarke, EclipseLink Project Lead, Oracle Integrating BIRT into Applications, Ashwini Verma, Actuate Corporation Leveraging OSGi In The Enterprise, Kamal Muralidharan, Lead Engineer, eBay Developing Rich ADF Applications with Java EE, Greg Stachnick, Oracle NVIDIA® NsightTM Eclipse Edition, Goodwin (Tech lead - Visual tools), Eugene Ostroukhov (Senior engineer – Visual tools) 2012 Oracle Fusion Middleware Innovation Awards - Win a FREE Pass to Oracle OpenWorld 2012 in San Francisco Share your use of Oracle Fusion Middleware solutions and how they help your organization drive business innovation. You just might win a free pass to Oracle Openworld 2012 in San Francisco. Deadline for submissions in July 17, 2012. BI Architecture Master Class for Partners – Oracle Architecture Unplugged Date: June 21, 2012 No slides, no fluff. This workshop will be highly interactive and is aimed at Oracle OPN member partners who are IT Architects and BI+W specialists. The focus will be on architectural issues and considerations. DevOps: Evolving to Handle Disruption | JP Morgenthal The subject of DevOps came up this week during an OTN ArchBeat podcast interview with Ron Batra and James Baty on the role of the cloud architect (that program will be available in a few weeks). Morgenthal's article for InfoQ offers a good overview of what DevOps is and how it works. Thought for the Day "Elegance is not a dispensable luxury but a factor that decides between success and failure." — Edsger Dijkstra Source: softwarequotes.com

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• Fastest pathfinding for static node matrix

  - by Sean Martin

  I'm programming a route finding routine in VB.NET for an online game I play, and I'm searching for the fastest route finding algorithm for my map type. The game takes place in space, with thousands of solar systems connected by jump gates. The game devs have provided a DB dump containing a list of every system and the systems it can jump to. The map isn't quite a node tree, since some branches can jump to other branches - more of a matrix. What I need is a fast pathfinding algorithm. I have already implemented an A* routine and a Dijkstra's, both find the best path but are too slow for my purposes - a search that considers about 5000 nodes takes over 20 seconds to compute. A similar program on a website can do the same search in less than a second. This website claims to use D*, which I have looked into. That algorithm seems more appropriate for dynamic maps rather than one that does not change - unless I misunderstand it's premise. So is there something faster I can use for a map that is not your typical tile/polygon base? GBFS? Perhaps a DFS? Or have I likely got some problem with my A* - maybe poorly chosen heuristics or movement cost? Currently my movement cost is the length of the jump (the DB dump has solar system coordinates as well), and the heuristic is a quick euclidean calculation from the node to the goal. In case anyone has some optimizations for my A*, here is the routine that consumes about 60% of my processing time, according to my profiler. The coordinateData table contains a list of every system's coordinates, and neighborNode.distance is the distance of the jump. Private Function findDistance(ByVal startSystem As Integer, ByVal endSystem As Integer) As Integer 'hCount += 1 'If hCount Mod 0 = 0 Then 'Return hCache 'End If 'Initialize variables to be filled Dim x1, x2, y1, y2, z1, z2 As Integer 'LINQ queries for solar system data Dim systemFromData = From result In jumpDataDB.coordinateDatas Where result.systemId = startSystem Select result.x, result.y, result.z Dim systemToData = From result In jumpDataDB.coordinateDatas Where result.systemId = endSystem Select result.x, result.y, result.z 'LINQ execute 'Fill variables with solar system data for from and to system For Each solarSystem In systemFromData x1 = (solarSystem.x) y1 = (solarSystem.y) z1 = (solarSystem.z) Next For Each solarSystem In systemToData x2 = (solarSystem.x) y2 = (solarSystem.y) z2 = (solarSystem.z) Next Dim x3 = Math.Abs(x1 - x2) Dim y3 = Math.Abs(y1 - y2) Dim z3 = Math.Abs(z1 - z2) 'Calculate distance and round 'Dim distance = Math.Round(Math.Sqrt(Math.Abs((x1 - x2) ^ 2) + Math.Abs((y1 - y2) ^ 2) + Math.Abs((z1 - z2) ^ 2))) Dim distance = firstConstant * Math.Min(secondConstant * (x3 + y3 + z3), Math.Max(x3, Math.Max(y3, z3))) 'Dim distance = Math.Abs(x1 - x2) + Math.Abs(z1 - z2) + Math.Abs(y1 - y2) 'hCache = distance Return distance End Function And the main loop, the other 30% 'Begin search While openList.Count() != 0 'Set current system and move node to closed currentNode = lowestF() move(currentNode.id) For Each neighborNode In neighborNodes If Not onList(neighborNode.toSystem, 0) Then If Not onList(neighborNode.toSystem, 1) Then Dim newNode As New nodeData() newNode.id = neighborNode.toSystem newNode.parent = currentNode.id newNode.g = currentNode.g + neighborNode.distance newNode.h = findDistance(newNode.id, endSystem) newNode.f = newNode.g + newNode.h newNode.security = neighborNode.security openList.Add(newNode) shortOpenList(OLindex) = newNode.id OLindex += 1 Else Dim proposedG As Integer = currentNode.g + neighborNode.distance If proposedG < gValue(neighborNode.toSystem) Then changeParent(neighborNode.toSystem, currentNode.id, proposedG) End If End If End If Next 'Check to see if done If currentNode.id = endSystem Then Exit While End If End While If clarification is needed on my spaghetti code, I'll try to explain.

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• How to prepare for a programming competition? Graphs, Stacks, Trees, oh my! [closed]

  - by Simucal

  Last semester I attended ACM's (Association for Computing Machinery) bi-annual programming competition at a local University. My University sent 2 teams of 3 people and we competed amongst other schools in the mid-west. We got our butts kicked. You are given a packet with about 11 problems (1 problem per page) and you have 4 hours to solve as many as you can. They'll run your program you submit against a set of data and your output must match theirs exactly. In fact, the judging is automated for the most part. In any case.. I went there fairly confident in my programming skills and I left there feeling drained and weak. It was a terribly humbling experience. In 4 hours my team of 3 people completed only one of the problems. The top team completed 4 of them and took 1st place. The problems they asked were like no problems I have ever had to answer before. I later learned that in order to solve them some of them effectively you have to use graphs/graph algorithms, trees, stacks. Some of them were simply "greedy" algo's. My question is, how can I better prepare for this semesters programming competition so I don't leave there feeling like a complete moron? What tips do you have for me to be able to answer these problems that involve graphs, trees, various "well known" algorithms? How can I easily identify the algorithm we should implement for a given problem? I have yet to take Algorithm Design in school so I just feel a little out of my element. Here are some examples of the questions asked at the competitions: ACM Problem Sets Update: Just wanted to update this since the latest competition is over. My team placed 1st for our small region (about 6-7 universities with between 1-5 teams each school) and ~15th for the midwest! So, it is a marked improvement over last years performance for sure. We also had no graduate students on our team and after reviewing the rules we found out that many teams had several! So, that would be a pretty big advantage in my own opinion. Problems this semester ranged from about 1-2 "easy" problems (ie bit manipulation, string manipulation) to hard (graph problems involving fairly complex math and network flow problems). We were able to solve 4 problems in our 5 hours. Just wanted to thank everyone for the resources they provided here, we used them for our weekly team practices and it definitely helped! Some quick tips that I have that aren't suggested below: When you are seated at your computer before the competition starts, quickly type out various data structures that you might need that you won't have access to in your languages libraries. I typed out a Graph data-structure complete with floyd-warshall and dijkstra's algorithm before the competition began. We ended up using it in our 2nd problem that we solved and this is the main reason why we solved this problem before anyone else in the midwest. We had it ready to go from the beginning. Similarly, type out the code to read in a file since this will be required for every problem. Save this answer "template" someplace so you can quickly copy/paste it to your IDE at the beginning of each problem. There are no rules on programming anything before the competition starts so get any boilerplate code out the way. We found it useful to have one person who is on permanent whiteboard duty. This is usually the person who is best at math and at working out solutions to get a head start on future problems you will be doing. One person is on permanent programming duty. Your fastest/most skilled "programmer" (most familiar with the language). This will save debugging time also. The last person has several roles between assessing the packet of problems for the next "easiest" problem, helping the person on the whiteboard work out solutions and helping the person programming work out bugs/issues. This person needs to be flexible and be able to switch between roles easily.

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• method for specialized pathfinding?

  - by rlbond

  I am working on a roguelike in my (very little) free time. Each level will basically be a few rectangular rooms connected together by paths. I want the paths between rooms to be natural-looking and windy, however. For example, I would not consider the following natural-looking: B X X X XX XX XX AXX I really want something more like this: B X XXXX X X X X AXXXXXXXX These paths must satisfy a few properties: I must be able to specify an area inside which they are bounded, I must be able to parameterize how windy and lengthy they are, The lines should not look like they started at one path and ended at the other. For example, the first example above looks as if it started at A and ended at B, because it basically changed directions repeatedly until it lined up with B and then just went straight there. I was hoping to use A*, but honestly I have no idea what my heuristic would be. I have also considered using a genetic algorithm, but I don't know how practical that method might end up. My question is, what is a good way to get the results I want? Please do not just specify a method like "A*" or "Dijkstra's algorithm," because I also need help with a good heuristic.

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• Calculate shortest path through a grocery store

  - by Bart

  Hi, I'm trying to find a way to find the shortest path through a grocery store, visiting a list of locations (shopping list). The path should start at a specified startposition and can end at multiple endpositions (there are multiple checkout counters). Also, I have some predefined constraints on the path, such as "item x on the shopping list needs to be the last, second last, or third last item on the path". There is a function that will return true or false for a given path. Finally, this needs to be calculated with limited cpu power (on a smartphone) and within a second or so. If this isn't possible, then an approximation to the optimal path is also ok. Is this possible? So far I think I need to start by calculating the distance between every item on the list using something like A* or Dijkstra's. After that, should I treat it like the travelling salesman problem? Because in my problem there is a specified startnode, specified endnodes, and some constraints, which are not in the travelling salesman problem. Any help would be appreciated :)

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• Where to post code for open source usage?

  - by Douglas

  I've been working for a few weeks now with the Google Maps API v3, and have done a good bit of development for the map I've been creating. Some of the things I've done have had to be done to add usability where there previously was not any, at least not that I could find online. Essentially, I made a list of what had to be done, searched all over the web for the ways to do what I needed, and found that some were not(at the time) possible(in the "grab an example off the web" sense). Thus, in my working on this map, I have created a number of very useful tools, which I would like to share with the development community. Is there anywhere I could use as a hub, apart from my portfolio ( http://dougglover.com ), to allow people to view and recycle my work? I know how hard it can be to need to do something, and be unable to find the solution elsewhere, and I don't think that if something has been done before, it should necessarily need to be written again and again. Hence open source code, right? Firstly, I was considering coming on here and asking a question, and then just answering it. Problem there is I assume that would just look like a big reputation grab. If not, please let me know and I'll go ahead and do that so people here can see it. Other suggestions appreciated. Some stuff I've made: A (new and improved) LatLng generator Works quicker, generates LatLng based on position of a draggable marker Allows searching for an address to place the marker on/near the desired location(much better than having to scroll to your location all the way from Siberia) Since it's a draggable marker, double-clicking zooms in, instead of creating a new LatLng marker like the one I was originally using The ability to create entirely custom "Smart Paths" Plot LatLng points on the map which connect to each other just like they do using the actual Google Maps Using Dijkstra's algorithm with Javascript, the routing is intelligent and always gives the shortest possible route, using the points provided Simple, easy to read multi-dimensional array system allows for easily adding new points to the grid Any suggestions, etc. appreciated.

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• How is this algorithm, for finding maximum path on a Directed Acyclical Graph, called?

  - by Martín Fixman

  Since some time, I'm using an algorithm that runs in complexity O(V + E) for finding maximum path on a Directed Acyclical Graph from point A to point B, that consists on doing a flood fill to find what nodes are accessible from note A, and how many "parents" (edges that come from other nodes) each node has. Then, I do a BFS but only "activating" a node when I already had used all its "parents". queue <int> a int paths[] ; //Number of paths that go to note i int edge[][] ; //Edges of a int mpath[] ; //max path from 0 to i (without counting the weight of i) int weight[] ; //weight of each node mpath[0] = 0 a.push(0) while not empty(a) for i in edge[a] paths[i] += 1 a.push(i) while not empty(a) for i in children[a] mpath[i] = max(mpath[i], mpath[a] + weight[a]) ; paths[i] -= 1 ; if path[i] = 0 a.push(i) ; Is there any special name for this algorithm? I told it to an Informatics professor, he just called it "Maximum Path on a DAG", but it doesn't sound good when you say "I solved the first problem with a Fenwick Tree, the second with Dijkstra, and the third with Maximum Path".

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• What algorithms compute directions from point A to point B on a map?

  - by A. Rex

  How do map providers (such as Google or Yahoo! Maps) suggest directions? I mean, they probably have real-world data in some form, certainly including distances but also perhaps things like driving speeds, presence of sidewalks, train schedules, etc. But suppose the data were in a simpler format, say a very large directed graph with edge weights reflecting distances. I want to be able to quickly compute directions from one arbitrary point to another. Sometimes these points will be close together (within one city) while sometimes they will be far apart (cross-country). Graph algorithms like Dijkstra's algorithm will not work because the graph is enormous. Luckily, heuristic algorithms like A* will probably work. However, our data is very structured, and perhaps some kind of tiered approach might work? (For example, store precomputed directions between certain "key" points far apart, as well as some local directions. Then directions for two far-away points will involve local directions to a key points, global directions to another key point, and then local directions again.) What algorithms are actually used in practice? PS. This question was motivated by finding quirks in online mapping directions. Contrary to the triangle inequality, sometimes Google Maps thinks that X-Z takes longer and is farther than using an intermediate point as in X-Y-Z. But maybe their walking directions optimize for another parameter, too? PPS. Here's another violation of the triangle inequality that suggests (to me) that they use some kind of tiered approach: X-Z versus X-Y-Z. The former seems to use prominent Boulevard de Sebastopol even though it's slightly out of the way. (Edit: this example doesn't work anymore, but did at the time of the original post. The one above still works as of early November 2009.)

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• Can knowing C actually hurt the code you write in higher level languages?

  - by Jurily

  The question seems settled, beaten to death even. Smart people have said smart things on the subject. To be a really good programmer, you need to know C. Or do you? I was enlightened twice this week. The first one made me realize that my assumptions don't go further than my knowledge behind them, and given the complexity of software running on my machine, that's almost non-existent. But what really drove it home was this Slashdot comment: The end result is that I notice the many naive ways in which traditional C "bare metal" programmers assume that higher level languages are implemented. They make bad "optimization" decisions in projects they influence, because they have no idea how a compiler works or how different a good runtime system may be from the naive macro-assembler model they understand. Then it hit me: C is just one more abstraction, like all others. Even the CPU itself is only an abstraction! I've just never seen it break, because I don't have the tools to measure it. I'm confused. Has my mind been mutilated beyond recovery, like Dijkstra said about BASIC? Am I living in a constant state of premature optimization? Is there hope for me, now that I realized I know nothing about anything? Is there anything to know, even? And why is it so fascinating, that everything I've written in the last five years might have been fundamentally wrong? To sum it up: is there any value in knowing more than the API docs tell me? EDIT: Made CW. Of course this also means now you must post examples of the interpreter/runtime optimizing better than we do :)

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• Graph search problem with route restrictions

  - by Darcara

  I want to calculate the most profitable route and I think this is a type of traveling salesman problem. I have a set of nodes that I can visit and a function to calculate cost for traveling between nodes and points for reaching the nodes. The goal is to reach a fixed known score while minimizing the cost. This cost and rewards are not fixed and depend on the nodes visited before. The starting node is fixed. There are some restrictions on how nodes can be visited. Some simplified examples include: Node B can only be visited after A After node C has been visited, D or E can be visited. Visiting at least one is required, visiting both is permissible. Z can only be visited after at least 5 other nodes have been visited Once 50 nodes have been visited, the nodes A-M will no longer reward points Certain nodes can (and probably must) be visited multiple times Currently I can think of only two ways to solve this: a) Genetic Algorithms, with the fitness function calculating the cost/benefit of the generated route b) Dijkstra search through the graph, since the starting node is fixed, although the large number of nodes will probably make that not feasible memory wise. Are there any other ways to determine the best route through the graph? It doesn't need to be perfect, an approximated path is perfectly fine, as long as it's error acceptable. Would TSP-solvers be an option here?

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• Goto for the Java Programming Language

  - by darcy

  Work on JDK 8 is well-underway, but we thought this late-breaking JEP for another language change for the platform couldn't wait another day before being published. Title: Goto for the Java Programming Language Author: Joseph D. Darcy Organization: Oracle. Created: 2012/04/01 Type: Feature State: Funded Exposure: Open Component: core/lang Scope: SE JSR: 901 MR Discussion: compiler dash dev at openjdk dot java dot net Start: 2012/Q2 Effort: XS Duration: S Template: 1.0 Reviewed-by: Duke Endorsed-by: Edsger Dijkstra Funded-by: Blue Sun Corporation Summary Provide the benefits of the time-testing goto control structure to Java programs. The Java language has a history of adding new control structures over time, the assert statement in 1.4, the enhanced for-loop in 1.5,and try-with-resources in 7. Having support for goto is long-overdue and simple to implement since the JVM already has goto instructions. Success Metrics The goto statement will allow inefficient and verbose recursive algorithms and explicit loops to be replaced with more compact code. The effort will be a success if at least twenty five percent of the JDK's explicit loops are replaced with goto's. Coordination with IDE vendors is expected to help facilitate this goal. Motivation The goto construct offers numerous benefits to the Java platform, from increased expressiveness, to more compact code, to providing new programming paradigms to appeal to a broader demographic. In JDK 8, there is a renewed focus on using the Java platform on embedded devices with more modest resources than desktop or server environments. In such contexts, static and dynamic memory footprint is a concern. One significant component of footprint is the code attribute of class files and certain classes of important algorithms can be expressed more compactly using goto than using other constructs, saving footprint. For example, to implement state machines recursively, some parties have asked for the JVM to support tail calls, that is, to perform a complex transformation with security implications to turn a method call into a goto. Such complicated machinery should not be assumed for an embedded context. A better solution is just to expose to the programmer the desired functionality, goto. The web has familiarized users with a model of traversing links among different HTML pages in a free-form fashion with some state being maintained on the side, such as login credentials, to effect behavior. This is exactly the programming model of goto and code. While in the past this has been derided as leading to "spaghetti code," spaghetti is a tasty and nutritious meal for programmers, unlike quiche. The invokedynamic instruction added by JSR 292 exposes the JVM's linkage operation to programmers. This is a low-level operation that can be leveraged by sophisticated programmers. Likewise, goto is a also a low-level operation that should not be hidden from programmers who can use more efficient idioms. Some may object that goto was consciously excluded from the original design of Java as one of the removed feature from C and C++. However, the designers of the Java programming languages have revisited these removals before. The enum construct was also left out only to be added in JDK 5 and multiple inheritance was left out, only to be added back by the virtual extension method methods of Project Lambda. As a living language, the needs of the growing Java community today should be used to judge what features are needed in the platform tomorrow; the language should not be forever bound by the decisions of the past. Description From its initial version, the JVM has had two instructions for unconditional transfer of control within a method, goto (0xa7) and goto_w (0xc8). The goto_w instruction is used for larger jumps. All versions of the Java language have supported labeled statements; however, only the break and continue statements were able to specify a particular label as a target with the onerous restriction that the label must be lexically enclosing. The grammar addition for the goto statement is: GotoStatement: goto Identifier ; The new goto statement similar to break except that the target label can be anywhere inside the method and the identifier is mandatory. The compiler simply translates the goto statement into one of the JVM goto instructions targeting the right offset in the method. Therefore, adding the goto statement to the platform is only a small effort since existing compiler and JVM functionality is reused. Other language changes to support goto include obvious updates to definite assignment analysis, reachability analysis, and exception analysis. Possible future extensions include a computed goto as found in gcc, which would replace the identifier in the goto statement with an expression having the type of a label. Testing Since goto will be implemented using largely existing facilities, only light levels of testing are needed. Impact Compatibility: Since goto is already a keyword, there are no source compatibility implications. Performance/scalability: Performance will improve with more compact code. JVMs already need to handle irreducible flow graphs since goto is a VM instruction.

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• Moose and error messages, the sun and the moon [closed]

  - by xxxxxxx

  So again using Moose I write a role like this: package My::Role; use Moose::Role; use Some::Class::Consuming::My::Role; With the note that Some::Class::Consuming::My::Role consumes the role My::Role; And what do I get ? I get an error message like this: A role generator is required to generate roles at /usr/local/share/perl/5.10.0/MooseX/Role/Parameterized/Meta/Role/Parameterizable.pm line 79 MooseX::Role::Parameterized::Meta::Role::Parameterizable::generate_role('MooseX::Role::Parameterized::Meta::Role::Parameterizable=HASH...', 'consumer', 'Moose::Meta::Class=HASH(0x894e540)', 'parameters', 'HASH(0x86fc1e0)') called at /usr/local/share/perl/5.10.0/MooseX/Role/Parameterized/Meta/Role/Parameterizable.pm line 116 MooseX::Role::Parameterized::Meta::Role::Parameterizable::apply('MooseX::Role::Parameterized::Meta::Role::Parameterizable=HASH...', 'Moose::Meta::Class=HASH(0x894e540)', 'element_type', 'Tuple') called at /usr/local/lib/perl/5.10.0/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0x894e540)', undef, 'Stuff', 'HASH(0x894e1d0)') called at /usr/local/lib/perl/5.10.0/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0x894e540)', 'Stuff', 'HASH(0x894e1d0)') called at /usr/local/lib/perl/5.10.0/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0x894e540)', 'Group', 'HASH(0x894e1d0)') called at /usr/local/lib/perl/5.10.0/Moose/Exporter.pm line 293 Moose::with('Group', 'HASH(0x894e1d0)') called at Some_path_on_disk line 6 require Some_other_path_on_disk called at Some_path_on_disk line 9 Group::BEGIN() called at Yet_another_path_on_disk line 0 eval {...} called at Yet_another_path_on_disk line 0 Compilation failed in require at some_path_on_disk line 9. BEGIN failed--compilation aborted at some_path_on_disk line 9. What am I to make of this ? As Dijkstra would concisely describe, this looks like "just a meaningless concatenation of words"(which is exactly what it is). Would a more appropriate error message be "You cannot use a class consuming the role that you are currently defining " ? What does the error message try to convey ? Can the author make the error message meaningful ? Will he ever make it so ? maybe this can be planned for version 3.14159265358979323846 ? In actuality I get one and a half pages of error which is completely unreadable and devoid of any logic or sense of respect for the user that is using Moose (in terms of intuitive error messages) just like the one above. What's to be done in this case ? I mean I get on my screen these error messages that are sometimes completely unrelated to the problem that I'm having (which I can assess after solving the problems that probably caused them, I say probably becuase I have no idea where these error messages came from because they look like they fell from the sky as they have no relation to the actual situation). Is this: the inexplicable dramatic destiny of the Perl programmer using Moose ? someone being extremely lazy and sloppy at writing error messages ? maybe on heavy drugs ? me not understanding basic english ? Gentlemen, when writing software, please please please, take care of the poor programmer that will use it and respect him by writing relevant error messages. (Except for error messages Moose is a pretty good piece of software)

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• Go - Using a container/heap to implement a priority queue

  - by Seth Hoenig

  In the big picture, I'm trying to implement Dijkstra's algorithm using a priority queue. According to members of golang-nuts, the idiomatic way to do this in Go is to use the heap interface with a custom underlying data structure. So I have created Node.go and PQueue.go like so: //Node.go package pqueue type Node struct { row int col int myVal int sumVal int } func (n *Node) Init(r, c, mv, sv int) { n.row = r n.col = c n.myVal = mv n.sumVal = sv } func (n *Node) Equals(o *Node) bool { return n.row == o.row && n.col == o.col } And PQueue.go: // PQueue.go package pqueue import "container/vector" import "container/heap" type PQueue struct { data vector.Vector size int } func (pq *PQueue) Init() { heap.Init(pq) } func (pq *PQueue) IsEmpty() bool { return pq.size == 0 } func (pq *PQueue) Push(i interface{}) { heap.Push(pq, i) pq.size++ } func (pq *PQueue) Pop() interface{} { pq.size-- return heap.Pop(pq) } func (pq *PQueue) Len() int { return pq.size } func (pq *PQueue) Less(i, j int) bool { I := pq.data.At(i).(Node) J := pq.data.At(j).(Node) return (I.sumVal + I.myVal) < (J.sumVal + J.myVal) } func (pq *PQueue) Swap(i, j int) { temp := pq.data.At(i).(Node) pq.data.Set(i, pq.data.At(j).(Node)) pq.data.Set(j, temp) } And main.go: (the action is in SolveMatrix) // Euler 81 package main import "fmt" import "io/ioutil" import "strings" import "strconv" import "./pqueue" const MATSIZE = 5 const MATNAME = "matrix_small.txt" func main() { var matrix [MATSIZE][MATSIZE]int contents, err := ioutil.ReadFile(MATNAME) if err != nil { panic("FILE IO ERROR!") } inFileStr := string(contents) byrows := strings.Split(inFileStr, "\n", -1) for row := 0; row < MATSIZE; row++ { byrows[row] = (byrows[row])[0 : len(byrows[row])-1] bycols := strings.Split(byrows[row], ",", -1) for col := 0; col < MATSIZE; col++ { matrix[row][col], _ = strconv.Atoi(bycols[col]) } } PrintMatrix(matrix) sum, len := SolveMatrix(matrix) fmt.Printf("len: %d, sum: %d\n", len, sum) } func PrintMatrix(mat [MATSIZE][MATSIZE]int) { for r := 0; r < MATSIZE; r++ { for c := 0; c < MATSIZE; c++ { fmt.Printf("%d ", mat[r][c]) } fmt.Print("\n") } } func SolveMatrix(mat [MATSIZE][MATSIZE]int) (int, int) { var PQ pqueue.PQueue var firstNode pqueue.Node var endNode pqueue.Node msm1 := MATSIZE - 1 firstNode.Init(0, 0, mat[0][0], 0) endNode.Init(msm1, msm1, mat[msm1][msm1], 0) if PQ.IsEmpty() { // make compiler stfu about unused variable fmt.Print("empty") } PQ.Push(firstNode) // problem return 0, 0 } The problem is, upon compiling i get the error message: [~/Code/Euler/81] $ make 6g -o pqueue.6 Node.go PQueue.go 6g main.go main.go:58: implicit assignment of unexported field 'row' of pqueue.Node in function argument make: *** [all] Error 1 And commenting out the line PQ.Push(firstNode) does satisfy the compiler. But I don't understand why I'm getting the error message in the first place. Push doesn't modify the argument in any way.

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• Problem on a Floyd-Warshall implementation using c++

  - by Henrique

  I've got a assignment for my college, already implemented Dijkstra and Bellman-Ford sucessfully, but i'm on trouble on this one. Everything looks fine, but it's not giving me the correct answer. Here's the code: void FloydWarshall() { //Also assume that n is the number of vertices and edgeCost(i,i) = 0 int path[500][500]; /* A 2-dimensional matrix. At each step in the algorithm, path[i][j] is the shortest path from i to j using intermediate vertices (1..k-1). Each path[i][j] is initialized to edgeCost(i,j) or infinity if there is no edge between i and j. */ for(int i = 0 ; i <= nvertices ; i++) for(int j = 0 ; j <= nvertices ; j++) path[i][j] = INFINITY; for(int j = 0 ; j < narestas ; j++) //narestas = number of edges { path[arestas[j]->v1][arestas[j]->v2] = arestas[j]->peso; //peso = weight of the edge (aresta = edge) path[arestas[j]->v2][arestas[j]->v1] = arestas[j]->peso; } for(int i = 0 ; i <= nvertices ; i++) //path(i, i) = 0 path[i][i] = 0; //test print, it's working fine //printf("\n\n\nResultado FloydWarshall:\n"); //for(int i = 1 ; i <= nvertices ; i++) // printf("distancia ao vertice %d: %d\n", i, path[1][i]); //heres the problem, it messes up, and even a edge who costs 4, and the minimum is 4, it prints 2. //for k = 1 to n for(int k = 1 ; k <= nvertices ; k++) //for i = 1 to n for(int i = 1 ; i <= nvertices ; i++) //for j := 1 to n for(int j = 1 ; j <= nvertices ; j++) if(path[i][j] > path[i][k] + path[k][j]) path[i][j] = path[i][k] + path[k][j]; printf("\n\n\nResultado FloydWarshall:\n"); for(int i = 1 ; i <= nvertices ; i++) printf("distancia ao vertice %d: %d\n", i, path[1][i]); } im using this graph example i've made: 6 7 1 2 4 1 5 1 2 3 1 2 5 2 5 6 3 6 4 6 3 4 2 means we have 6 vertices (1 to 6), and 7 edges (1,2) with weight 4... etc.. If anyone need more info, i'm up to giving it, just tired of looking at this code and not finding an error.

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• Finding contained bordered regions from Excel imports.

  - by dmaruca

  I am importing massive amounts of data from Excel that have various table layouts. I have good enough table detection routines and merge cell handling, but I am running into a problem when it comes to dealing with borders. Namely performance. The bordered regions in some of these files have meaning. Data Setup: I am importing directly from Office Open XML using VB6 and MSXML. The data is parsed from the XML into a dictionary of cell data. This wonks wonderfully and is just as fast as using docmd.transferspreadsheet in Access, but returns much better results. Each cell contains a pointer to a style element which contains a pointer to a border element that defines the visibility and weight of each border (this is how the data is structured inside OpenXML, also). Challenge: What I'm trying to do is find every region that is enclosed inside borders, and create a list of cells that are inside that region. What I have done: I initially created a BFS(breadth first search) fill routine to find these areas. This works wonderfully and fast for "normal" sized spreadsheets, but gets way too slow for imports into the thousands of rows. One problem is that a border in Excel could be stored in the cell you are checking or the opposing border in the adjacent cell. That's ok, I can consolidate that data on import to reduce the number of checks needed. One thing I thought about doing is to create a separate graph that outlines the cells using the borders as my edges and using a graph algorithm to find regions that way, but I'm having trouble figuring out how to implement the algorithm. I've used Dijkstra in the past and thought I could do similar with this. So I can span out using no endpoint to search the entire graph, and if I encounter a closed node I know that I just found an enclosed region, but how can I know if the route I've found is the optimal one? I guess I could flag that to run a separate check for the found closed node to the previous node ignoring that one edge. This could work, but wouldn't be much better performance wise on dense graphs. Can anyone else suggest a better method? Thanks for taking the time to read this.

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• backbone.js - Having multiple instances of the same view

  - by TrueWheel

  I am having problems having multiple instances in of the same view in different div elements. When I try to initialize them only the second of the two elements appear no matter what order I put them in. Here is the code for my view. var BodyShapeView = Backbone.View.extend({ thingiview: null, scene: null, renderer: null, model: null, mouseX: 0, mouseY: 0, events:{ 'click button#front' : 'front', 'click button#diag' : 'diag', 'click button#in' : 'zoomIn', 'click button#out' : 'zoomOut', 'click button#on' : 'rotateOn', 'click button#off' : 'rotateOff', 'click button#wireframeOn' : 'wireOn', 'click button#wireframeOff' : 'wireOff', 'click button#distance' : 'dijkstra' }, initialize: function(name){ _.bindAll(this, 'render', 'animate'); scene = new THREE.Scene(); camera = new THREE.PerspectiveCamera( 15, 400 / 700, 1, 4000 ); camera.position.z = 3; scene.add( camera ); camera.position.y = -5; var ambient = new THREE.AmbientLight( 0x202020 ); scene.add( ambient ); var directionalLight = new THREE.DirectionalLight( 0xffffff, 0.75 ); directionalLight.position.set( 0, 0, 1 ); scene.add( directionalLight ); var pointLight = new THREE.PointLight( 0xffffff, 5, 29 ); pointLight.position.set( 0, -25, 10 ); scene.add( pointLight ); var loader = new THREE.OBJLoader(); loader.load( "img/originalMeanModel.obj", function ( object ) { object.children[0].geometry.computeFaceNormals(); var geometry = object.children[0].geometry; console.log(geometry); THREE.GeometryUtils.center(geometry); geometry.dynamic = true; var material = new THREE.MeshLambertMaterial({color: 0xffffff, shading: THREE.FlatShading, vertexColors: THREE.VertexColors }); mesh = new THREE.Mesh(geometry, material); model = mesh; // model = object; scene.add( model ); } ); // RENDERER renderer = new THREE.WebGLRenderer(); renderer.setSize( 400, 700 ); $(this.el).find('.obj').append( renderer.domElement ); this.animate(); }, Here is how I create the instances var morphableBody = new BodyShapeView({ el: $("#morphable-body") }); var bodyShapeView = new BodyShapeView({ el: $("#mean-body") }); Any help would be really appreciated. Thanks in advance.

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• BFS Shortest Path: Edge weight either 1 or 2

  - by Hackster

  I am trying to implement a shortest path algorithm using BFS. That is I am trying to find the shortest path from a specified vertex to every other vertex. However, its a special case where all edge weights are either 1 or 2. I know it could be done with Dijkstra's algorithm but I must use Breadth First Search. So far I have a working version of BFS that searches first for a vertex connected with an edge of weight 1. If it cannot find it, then returns a vertex connected with an edge of weight 2. After thinking about it, this is not the correct way to find the shortest path. The problem is I cannot think of any reasoning why BFS would work with weights 1 or 2, as opposed to any weight. Here is the code: public void addEdge(int start, int end, int weight) { adjMat[start][end] = 1; adjMat[end][start] = 1; edge_weight[start][end] = weight; edge_weight[end][start] = weight; } // ------------------------------------------------------------- public void bfs() // breadth-first search { // begin at vertex 0 vertexList[0].wasVisited = true; // mark it displayVertex(0); // display it theQueue.insert(0); // insert at tail int v2; while( !theQueue.isEmpty() ) // until queue empty, { int v1 = theQueue.remove(); // remove vertex at head // until it has no unvisited neighbors while( (v2=getAdjUnvisitedVertex(v1)) != -1 ){// get one, vertexList[v2].wasVisited = true; // mark it displayVertex(v2); // display it theQueue.insert(v2); // insert it } } // end while(queue not empty) // queue is empty, so we're done for(int j=0; j<nVerts; j++) // reset flags vertexList[j].wasVisited = false; } // end bfs() // ------------------------------------------------------------- // returns an unvisited vertex adj to v -- ****WITH WEIGHT 1**** public int getAdjUnvisitedVertex(int v) { for (int j = 0; j < nVerts; j++) if (adjMat[v][j] == 1 && vertexList[j].wasVisited == false && edge_weight[v][j] == 1){ //System.out.println("Vertex found with 1:"+ vertexList[j].label); return j; } for (int k = 0; k < nVerts; k++) if (adjMat[v][k] == 1 && vertexList[k].wasVisited == false && edge_weight[v][k] == 2){ //System.out.println("Vertex found with 2:"+vertexList[k].label); return k; } return -1; } // end getAdjUnvisitedVertex() // ------------------------------------------------------------- } //////////////////////////////////////////////////////////////// public class BFS{ public static void main(String[] args) { Graph theGraph = new Graph(); theGraph.addVertex('A'); // 0 (start for bfs) theGraph.addVertex('B'); // 1 theGraph.addVertex('C'); // 2 theGraph.addEdge(0, 1,2); // AB theGraph.addEdge(1, 2,1); // BC theGraph.addEdge(2, 0,1); // AD System.out.print("Visits: "); theGraph.bfs(); // breadth-first search System.out.println(); } // end main() } The problem then is, that I don't know why BFS can work for the shortest path problem with edges of weight 1 or 2 as opposed to any edges of any weight. Any help is appreciated. Thanks!

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• CodePlex Daily Summary for Saturday, August 02, 2014

  CodePlex Daily Summary for Saturday, August 02, 2014Popular ReleasesRecaptcha for .NET: Recaptcha for .NET v1.5.1: Added support for HTTPS. Signed the assemblies.PowerShell App Deployment Toolkit: PowerShell App Deployment Toolkit v3.1.5: *Added Send-Keys function to send a sequence of keys to an application window (Thanks to mmashwani) *Added 3 optimization/stability improvements to Execute-Process following MS best practice (Thanks to mmashwani) *Fixed issue where Execute-MSI did not use value from XML file for uninstall but instead ran all uninstalls silently by default *Fixed error on 1641 exit code (should be a success like 3010) *Fixed issue with error handling in Invoke-SCCMTask *Fixed issue with deferral dates where th...AutoUpdater.NET : Auto update library for VB.NET and C# Developer: AutoUpdater.NET 1.3: Fixed problem in DownloadUpdateDialog where download continues even if you close the dialog. Added support for new url field for 64 bit application setup. AutoUpdater.NET will decide which download url to use by looking at the value of IntPtr.Size. Added German translation provided by Rene Kannegiesser. Now developer can handle update logic herself using event suggested by ricorx7. Added italian translation provided by Gianluca Mariani. Fixed bug that prevents Application from exiti...SEToolbox: SEToolbox 01.041.012 Release 1: Added voxel material textures to read in with mods. Fixed missing texture replacements for mods. Fixed rounding issue in raytrace code. Fixed repair issue with corrupt checkpoint file. Fixed issue with updated SE binaries 01.041.012 using new container configuration.Magick.NET: Magick.NET 6.8.9.601: Magick.NET linked with ImageMagick 6.8.9.6 Breaking changes: - Changed arguments for the Map method of MagickImage. - QuantizeSettings uses Riemersma by default.SharePoint Real Time Log Viewer: SharePoint Real Time Log Viewer - Source: Source codeModern Audio Tagger: Modern Audio Tagger 1.0.0.0: Modern Audio Tagger is bornQuickMon: Version 3.20: Added a 'Directory Services Query' collector agent. This collector allows for querying Active Directory using simple DirectorySearcher queries.Grunndatakvalitet: Initial working: Show Altinn metadata in Excel. To get a live list you need to run the sql script on a server and update the connection string in ExcelMultiple Threads TCP Server: Project: this Project is based on VS 2013, .net freamwork 4.0, you can open it by vs 2010 or laterAccesorios de sitios Torrent en Español para Synology Download Station: Pack de Torrents en Español 6.0.0: Agregado los módulos de DivXTotal, el módulo de búsqueda depende del de alojamiento para bajar las series Utiliza el rss: http://www.divxtotal.com/rss.php DbEntry.Net (Leafing Framework): DbEntry.Net 4.2: DbEntry.Net is a lightweight Object Relational Mapping (ORM) database access compnent for .Net 4.0+. It has clearly and easily programing interface for ORM and sql directly, and supoorted Access, Sql Server, MySql, SQLite, Firebird, PostgreSQL and Oracle. It also provide a Ruby On Rails style MVC framework. Asp.Net DataSource and a simple IoC. DbEntry.Net.v4.2.Setup.zip include the setup package. DbEntry.Net.v4.2.Src.zip include source files and unit tests. DbEntry.Net.v4.2.Samples.zip ...Azure Storage Explorer: Azure Storage Explorer 6 Preview 1: Welcome to Azure Storage Explorer 6 Preview 1 This is the first release of the latest Azure Storage Explorer, code-named Phoenix. What's New?Here are some important things to know about version 6: Open Source Now being run as a full open source project. Full source code on CodePlex. Collaboration encouraged! Updated Code Base Brand-new code base (WPF/C#/.NET 4.5) Visual Studio 2013 solution (previously VS2010) Uses the Task Parallel Library (TPL) for asynchronous background operat...Wsus Package Publisher: release v1.3.1407.29: Updated WPP to recognize the very latest console version. Some files was missing into the latest release of WPP which lead to crash when trying to make a custom update. Add a workaround to avoid clipboard modification when double-clicking on a label when creating a custom update. Add the ability to publish detectoids. (This feature is still in a BETA phase. Packages relying on these detectoids to determine which computers need to be updated, may apply to all computers).VG-Ripper & PG-Ripper: PG-Ripper 1.4.32: changes NEW: Added Support for 'ImgMega.com' links NEW: Added Support for 'ImgCandy.net' links NEW: Added Support for 'ImgPit.com' links NEW: Added Support for 'Img.yt' links FIXED: 'Radikal.ru' links FIXED: 'ImageTeam.org' links FIXED: 'ImgSee.com' links FIXED: 'Img.yt' linksAsp.Net MVC-4,Entity Framework and JQGrid Demo with Todo List WebApplication: Asp.Net MVC-4,Entity Framework and JQGrid Demo: Asp.Net MVC-4,Entity Framework and JQGrid Demo with simple Todo List WebApplication, Overview TodoList is a simple web application to create, store and modify Todo tasks to be maintained by the users, which comprises of following fields to the user (Task Name, Task Description, Severity, Target Date, Task Status). TodoList web application is created using MVC - 4 architecture, code-first Entity Framework (ORM) and Jqgrid for displaying the data.Waterfox: Waterfox 31.0 Portable: New features in Waterfox 31.0: Added support for Unicode 7.0 Experimental support for WebCL New features in Firefox 31.0:New Add the search field to the new tab page Support of Prefer:Safe http header for parental control mozilla::pkix as default certificate verifier Block malware from downloaded files Block malware from downloaded files audio/video .ogg and .pdf files handled by Firefox if no application specified Changed Removal of the CAPS infrastructure for specifying site-sp...SuperSocket, an extensible socket server framework: SuperSocket 1.6.3: The changes below are included in this release: fixed an exception when collect a server's status but it has been stopped fixed a bug that can cause an exception in case of sending data when the connection dropped already fixed the log4net missing issue for a QuickStart project fixed a warning in a QuickStart projectYnote Classic: Ynote Classic 2.8.5 Beta: Several Changes - Multiple Carets and Multiple Selections - Improved Startup Time - Improved Syntax Highlighting - Search Improvements - Shell Command - Improved StabilityTEBookConverter: 1.2: Fixed: Could not start convertion in some cases Fixed: Progress show during convertion was truncated Fixed: Stopping convertion didn't reset program titleNew ProjectsCoder Camps Troop 64 7-28: Place for group projectsEasyMR: ????EasyMR???????????????????????????????，?????，????，????，????????，??????????????????????，????????????。??????Hadoop?????????，EasyMR???????，??????????????????。FlexGraph: A simple chart control for Windows delivered in form of a function DLL. Tested in C++ (MFC, QT), C# and VB.Net.Grunndatakvalitet: Project is meant to open up the Altinn national data hub for Access from other systems and eg self-service like ExcelKinect Avateering V2 SDK migration: Kinect V2 (new version with XBOX1) SDK Avatar Avateering sample migration from version 1.8SDK. lqwe: just devlzsoft-cdn: this is a projectMin Heap: MinHeap project provides a MinHeap implementation in C# for use in Dijkstra's algorithm for computing shortest path distances for non-negative edge lengths.Modern Audio Tagger: Modern Audio Tagger is a powerful, easy and extreme fast tool to reorganize your music libraryMultiple Threads TCP Server: A multi-threaded tcp server. Using a queue with multiple threads to handle large numbers of client requests.newTeamProject1: Game Minesweeper on Console ApplicationO(1): Scale-able partitioned pure .NET Property Graph Database intended to handle large complex graphs and provide high performance OLTP property graph capabilities.Orchard Single Page Application Theme: Orchard Single Page Application ( SPA ) ThemePersonal Assistance Suite (PAS): This C# project aims to set up a modular platform for private use. Microsoft Prism Library 5.0 for WPF is used to implement this modularity.PokitDok Platform API Client for C#: The PokitDok API allows you to perform X12 transactions, find healthcare providers, and get information on health care procedure pricing. REST, JSON, Oauth2.Powershell DSC Resource - cXML: Powershell DSC Resource Module for managing XML element in a text file.Powershell Uninstall Java: Identifies and uninstalls Java software from the local machine using WMI. The query to locate the installed software interogates the WIN32_Products claSharePoint Real Time Log Viewer: SharePoint Real Time Log Viewer is a winform application that allows you to view the logs generated by SharePoint.sqldataexporter: this is a projectVAK: we are trying to create an application that will be a place people can discuss IT related topics and also try to integrate lync 2013Windows Phone 8 DropBox API: Windows Phone REST API for DropBoxYet Another Steam Mover (YASM): Yet Another Steam Mover (YASM) is a Microsoft.NET Windows Forms application for moving large digital games across different volumes.

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