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• PostgreSQL: Auto-partition a table

  - by Adam Matan

  Hi, I have a huge database which holds pairs of numbers (A,B), each ranging from 0 to 10,000 and stored as floats. e.g., (1, 9984.4), (2143.44, 124.243), (0.55, 0), ... Since the PostgreSQL table which stores these pairs grew quite large, I have decided to partition it into inheriting sub-tables. I intend to create 100 such tables, each storing a range of 1000x1000. The problem is that these numbers tend to come in large chunks of nearby numbers. It means that in the future, some tables will be nearly empty and some will hold a very large portion of the database. Unfortunately, the distribution of future pairs is yet unknown. I am looking for a way to automatically repartition my table. That means that if a certain subtable holds more than a specific number of pairs, it will be automatically partitioned into four sub-sub tables, and so on. My questions are: Is recursive partitioning and inheritance possible in PostgreSQL 8.3? Will indexes and query plans understand it? What's the best way to split a subtable once it grew too large? I should point out that this isn't a live database, so a downtime of few hours every week is totally acceptable. Thanks in advance, Adam

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• Android ignores scrollbarsize

  - by Maragues

  Hi, I'm trying to modify a ListView scrollbar's width without success <ListView android:id="@+id/android:list" android:layout_width="fill_parent" android:layout_height="wrap_content" android:choiceMode="singleChoice" android:scrollbars="vertical" android:scrollbarTrackVertical="@drawable/scrollbar_vertical_track" android:scrollbarThumbVertical="@drawable/scrollbar_vertical_thumb" android:scrollbarSize="4px" android:clickable="true"/> First I tried using a drawable image 4px wide, but the .png was resized. Then I tried using a shape extracted from SamplesApi, without success. <shape xmlns:android="http://schemas.android.com/apk/res/android" android:width="40px"> <gradient android:startColor="#505050" android:endColor="#C0C0C0" android:angle="0"/> <corners android:radius="0dp" /> I've tried with and without the android:width attribute. There's a question on the same topic (http://stackoverflow.com/questions/2565083/width-of-a-scroll-bar-in-android), but it doesn't try anything different that what I'm already trying. As far as I know, creating my own theme shouldn't change the output. There's an example in SamplesApi (Views/ScrollBars). I tried modifying the scrollbarSize attribute without result. I know about ninepatch images, but there's an attribute which should do what I want. Any hint? Thanks in advance.

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• iPhone contacts app styled indexed table view implementation

  - by KSH

  My Requirement: I have this straight forward requirement of listing names of people in alphabetical order in a Indexed table view with index titles being the starting letter of alphabets (additionally a search icon at the top and # to display misc values which start with a number and other special characters). What I have done so far: 1. I am using core data for storage and "last_name" is modelled as a String property in the Contacts entity 2.I am using a NSFetchedResultsController to display the sorted indexed table view. Issues accomplishing my requirement: 1. First up, I couldn't get the section index titles to be the first letter of alphabets. Dave's suggestion in the following post, helped me achieve the same: http://stackoverflow.com/questions/1112521/nsfetchedresultscontroller-with-sections-created-by-first-letter-of-a-string The only issue I encountered with Dave' suggestion is that I couldn't get the misc named grouped under "#" index. What I have tried: 1. I tried adding a custom compare method to NSString (category) to check how the comparison and section is made but that custom method doesn't get called when specified in the NSSortDescriptor selector. Here is some code: `@interface NSString (SortString) -(NSComparisonResult) customCompare: (NSString*) aStirng; @end @implementation NSString (SortString) -(NSComparisonResult) customCompare:(NSString *)aString { NSLog(@"Custom compare called to compare : %@ and %@",self,aString); return [self caseInsensitiveCompare:aString]; } @end` Code to fetch data: `NSArray *sortDescriptors = [NSArray arrayWithObject:[[[NSSortDescriptor alloc] initWithKey:@"last_name" ascending:YES selector:@selector(customCompare:)] autorelease]]; [fetchRequest setSortDescriptors:sortDescriptors]; fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:@"lastNameInitial" cacheName:@"MyCache"];` Can you let me know what I am missing and how the requirement can be accomplished ?

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• Routing audio from GSM module to a Bluetooth HandsFree device

  - by Shaihi

  I have a system with the following setup: I use: Windows CE 6 R3 Microsoft's Bluetooth stack including all profiles Motorola H500 The Audio Gateway service is up and running (checked through services list in cmd) GSM Module is functional - I am able to set outgoing calls and to answer calls. Bluetooth is functional - the A2DP profile plays music to Motorola headphones (can't remember the model right now) I want to hold a conversation using a headset device. I have included all Bluetooth components in the catalog. I pair the device using the Control Panel applet. When I press the button on the Motorla device to answer a call I get a print by the Audio Gateway: BTAGSVC: ConnectionEvent. BTAGSVC: SCOListenThread_Int - Connection Event. BTAGSVC: ConnectionEvent. BTAGSVC: SCOListenThread_Int - Connection Event. BTAGSVC: ConnectionEvent. BTAGSVC: A Bluetooth peer device has connected to the Audio Gateway. BTAGSVC: Could not open registry key for BT Addr: 2. BTAGSVC: The peer device was not accepted since the user has never confirmed it as a device to be used. So my questions are as follows: What do I need to do to pair the device with the Audio Gateway? Once my device is paired, do I need to set anything else up? (except for the GSM module of course)

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• Non RBAC User Roles and Permissions System: checking the user's City

  - by micha12

  We are currently designing a User Roles and Permissions System in our web application (ASP.NET), and it seems that we have several cases that do no fit within the classical Role-Based Access Control (RBAC). I will post several questions, each devoted to a particular case, this being the first post. We have the following case: not to allow a user view a certain page if the user lives in a particular city. This is a simple case that is coded in the following way: if (User.City == “Moscow”) // Allow the user to view the page. else // Do not allow the user to view this page. Though this case is very simple and straightforward, it has nothing to do with the RBAC. On StackOverflow, someone called this an Attribute-based Access Control. Under the classical RBAC, it seems that this case should be designed like this: introduce a permission “City where the person lives”, this permission will have a property City. Then create a role, add a permission of type “City = Moscow” to it and the assign the role to the user. Looks extremely cumbersome. The question is whether it is acceptable to introduce such non-RBAC approaches to our permissions system – does that break the design or not? This might seem a primitive question, but we found that most applications use pure RBAC, and we started to think that we might be doing something wrong. Thank you.

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• Right to Left UI in iPhone (Hebrew)

  - by Reflog

  Hello, I'm struggling in creating a RTL UI in iPhone application. The framework doesn't seem to have any support for RTL languages. The only thing is the alignment inside labels, which is nice, but it conflicts with other controls behaviour. The question is: Is there a working code for a RTL TableView? Something that would handle the disclosure buttons to be on the left, section titles to be right aligned, index view to be left aligned? As far as I understand I cannot move the index view of the tableview, i have to overlay some custom control... Any suggestions/pointers/examples? p.s. this is not a duplication of this question: http://stackoverflow.com/questions/1677988/right-to-left-alignment-for-uitableview since what I am looking for is a deeper customization, not just a new type of CellView. (Update: Mar 10) For now - I've removed support for indexView from the tableView at all, implemented the cells as custom views by myself (with disclosure buttons on the left), and customized the header/footer of the table as well. the only thing that is left is the Index View. Thanks in advance!

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• how to handle an asymptote/discontinuity with Matplotlib

  - by Geddes

  Hello all. Firstly - thanks again for all your help. Sorry not to have accepted the responses to my previous questions as I did not know how the system worked (thanks to Mark for pointing that out!). I have since been back and gratefully acknowledged the kind help I have received. My question: when plotting a graph with a discontinuity/asymptote/singularity/whatever, is there any automatic way to prevent Matplotlib from 'joining the dots' across the 'break'? (please see code/image below). I read that Sage has a [detect_poles] facility that looked good, but I really want it to work with Matplotlib. Thanks and best wishes, Geddes import matplotlib.pyplot as plt import numpy as np from sympy import sympify, lambdify from sympy.abc import x fig = plt.figure(1) ax = fig.add_subplot(111) # set up axis ax.spines['left'].set_position('zero') ax.spines['right'].set_color('none') ax.spines['bottom'].set_position('zero') ax.spines['top'].set_color('none') ax.xaxis.set_ticks_position('bottom') ax.yaxis.set_ticks_position('left') # setup x and y ranges and precision xx = np.arange(-0.5,5.5,0.01) # draw my curve myfunction=sympify(1/(x-2)) mylambdifiedfunction=lambdify(x,myfunction,'numpy') ax.plot(xx, mylambdifiedfunction(xx),zorder=100,linewidth=3,color='red') #set bounds ax.set_xbound(-1,6) ax.set_ybound(-4,4) plt.show()

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• Algorithm to match list of regular expressions

  - by DSII

  I have two algorithmic questions for a project I am working on. I have thought about these, and have some suspicions, but I would love to hear the community's input as well. Suppose I have a string, and a list of N regular expressions (actually they are wildcard patterns representing a subset of full regex functionality). I want to know whether the string matches at least one of the regular expressions in the list. Is there a data structure that can allow me to match the string against the list of regular expressions in sublinear (presumably logarithmic) time? This is an extension of the previous problem. Suppose I have the same situation: a string and a list of N regular expressions, only now each of the regular expressions is paired with an offset within the string at which the match must begin (or, if you prefer, each of the regular expressions must match a substring of the given string beginning at the given offset). To give an example, suppose I had the string: This is a test string and the regex patterns and offsets: (a) his.* at offset 0 (b) his.* at offset 1 The algorithm should return true. Although regex (a) does not match the string beginning at offset 0, regex (b) does match the substring beginning at offset 1 ("his is a test string"). Is there a data structure that can allow me to solve this problem in sublinear time? One possibly useful piece of information is that often, many of the offsets in the list of regular expressions are the same (i.e. often we are matching the substring at offset X many times). This may be useful to leverage the solution to problem #1 above. Thank you very much in advance for any suggestions you may have!

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• Prefuse: Reloading of XML files

  - by John

  Hello all, I am a new to the prefuse visualization toolkit and have a couple of general questions. For my purpose, I would like to perform an initial visualization using prefuse (graphview / graphml). Once rendered, upon a user click of a node, I would like to completely reload a new xml file for a new visualization. I want to do this in order to allow me to "pre-package" graphs for display. For example. If I search for Ted. I would like to have an xml file relating to Ted load and render a display. Now in the display I see that Ted has nodes associated called Bill and Joe. When I click Joe, I would like to clear the display and load an xml file associated with Joe. And so on. I have looked into loading one very large xml file containing all node and node relationship info and allowing prefuse to handle this using the hops from one level to another. However, eventually I am sure that system performance issues will arise due to the size of data. Thanks in advance for any help, John

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• How should bug tracking and help tickets integrate?

  - by Max Schmeling

  I have a little experience with bug tracking systems such as FogBugz where help tickets are issues are (or can be) bugs, and I have some experience using a bug tracking system internally completely separate from a help center system. My question is, in a company with an existing (home-grown) help center system where replacing it is not an option, how should a bug tracking system (probably Mantis) be integrated into the process? Right now help tickets get put in for issues, questions, etc and they get assigned to the appropriate person (PC Tech, Help Desk staff, or if it's an application issue they can't solve in the help desk it gets assigned to a developer). A user can put a request for small modifications or fixes to an application in a help ticket and the developer it gets assigned to will make the change at some point, apply their time to that ticket, and then close the ticket when it goes to production. We don't currently have a bug tracking system, so I'm looking into the best way to integrate one. Should we just take the help tickets and put it into the bug tracking system if it's a bug (or issue or feature request) and then close the ticket if it's not an emergency fix? We probably don't want to expose the bug tracking system to anyone else as they wouldn't know what to put in the help center system and what to put in the bug tracker... right? Any thoughts? Suggestions? Tips? Advice? To-dos? Not to-dos? etc...

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• Variant datatype library for C

  - by Joey Adams

  Is there a decent open-source C library for storing and manipulating dynamically-typed variables (a.k.a. variants)? I'm primarily interested in atomic values (int8, int16, int32, uint, strings, blobs, etc.), while JSON-style arrays and objects as well as custom objects would also be nice. A major case where such a library would be useful is in working with SQL databases. The most obvious feature of such a library would be a single type for all supported values, e.g.: struct Variant { enum Type type; union { int8_t int8_; int16_t int16_; // ... }; }; Other features might include converting Variant objects to/from C structures (using a binding table), converting values to/from strings, and integration with an existing database library such as SQLite. Note: I do not believe this is question is a duplicate of http://stackoverflow.com/questions/649649/any-library-for-generic-datatypes-in-c , which refers to "queues, trees, maps, lists". What I'm talking about focuses more on making working with SQL databases roughly as smooth as working with them in interpreted languages.

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• How to get all active parameters in ASP.NET MVC (2)

  - by SztupY

  Hi! I was wondering whether there is a way to create an ActionLink or similar, that changes only a few parameters of the actual query, and keeps all the other parameters intact. For example if I'm on an URL like http://example.com/Posts/Index?Page=5&OrderBy=Name&OrderDesc=True I want to change only the Page, or OrderBy parameter and keep all other parameters the same, even those I don't yet know of (like when I want to add a Search parameter or something similar too). The header of my current action looks like this: public ActionResult Index(int? Page, string OrderBy, bool? Desc) and I'm only interested in the values that this controller "eats". I want however that when I extend this action (for example with a string Search parameter) the links should work the same way as before. Here is what I did already: Create a new RouteValueDictionary and fill it with everything from RouteData.Values Problem: This only fills the parameters that are used in the Routing, so all other optional parameters (like Page) to the controller are lost Add everything from HttpContext.Request.QueryString to the previous dictionary This is what I am currently using Problem: It might have some junk stuff, that the Controller didn`t ask for, and it doesn't work if the page was loaded using POST. You also don't have any ModelBindings (but this isn't much of a problem, because we are re-sending everything anyway) Use HttpContext.Request.Params Problem: this has too much junk data which imho one shouldn't add to a RouteValueDictionary that is passed to an ActionLink So the questions: Is there an RVD that has all the data that was passed to the Controller and was used by it? Is this solution good, or are there any caveats I didn't think about (mainly in the context of changing a few query parameters while keeping the others intact)? Is there a way to filter out the "junk" data from the Params object?

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• How to stop MVC caching the results of invoking and action method?

  - by Trey Carroll

  I am experiencing a problem with IE caching the results of an action method. Other articles I found were related to security and the [Authorize] attribute. This problem has nothing to do with security. This is a very simple "record a vote, grab the average, return the avg and the number of votes" method. The only slightly interesting thing about it is that it is invoked via Ajax and returns a Json object. I believe that it is the Json object that is getting catched. When I run it from FireFox and watch the XHR traffic with Firebug, everything works perfectly. However, under IE 8 the "throbber" graphic doesn't ever have time to show up and the page elements that display the "new" avg and count that are being injected into the page with jQuery are never different. I need a way to tell MVC to never cache this action method. This article seems to address the problem, but I cannot understand it: http://stackoverflow.com/questions/1441467/prevent-caching-of-attributes-in-asp-net-mvc-force-attribute-execution-every-tim I need a bit more context for the solution to understand how to extend AuthorizationAttribute. Please address your answer as if you were speaking to someone who lacks a deep understanding of MVC even if that means replying with an article on some basics/prerequisites that are required. Thanks, Trey Carroll

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• Why does my Delphi program's memory continue to grow?

  - by lkessler

  I am using Delphi 2009 which has the FastMM4 memory manager built into it. My program reads in and processes a large dataset. All memory is freed correctly whenever I clear the dataset or exit the program. It has no memory leaks at all. Using the CurrentMemoryUsage routine given in spenwarr's answer to: http://stackoverflow.com/questions/437683/how-to-get-the-memory-used-by-a-delphi-program, I have displayed the memory used by FastMM4 during processing. What seems to be happening is that memory is use is growing after every process and release cycle. e.g.: 1,456 KB used after starting my program with no dataset. 218,455 KB used after loading a large dataset. 71,994 KB after clearing the dataset completely. If I exit at this point (or any point in my example), no memory leaks are reported. 271,905 KB used after loading the same dataset again. 125,443 KB after clearing the dataset completely. 325,519 KB used after loading the same dataset again. 179,059 KB after clearing the dataset completely. 378,752 KB used after loading the same dataset again. It seems that my program's memory use is growing by about 53,400 KB upon each load/clear cycle. Task Manager confirms that this is actually happening. I have heard that FastMM4 does not always release all of the program's memory back to the Operating system when objects are freed so that it can keep some memory around when it needs more. But this continual growing bothers me. Since no memory leaks are reported, I can't identify a problem. Does anyone know why this is happening, if it is bad, and if there is anything I can or should do about it?

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• how to create Java Application and query about OWL using SPARQL/Jena and how to do it on local/remot

  - by user323889

  I want to create simple application using Java Jena and SPARQL ,that insert, delete , update and query the OWL/RDF data I worked on protege to create the ontology and noticed SPARQL in it but I want to use SPARQL using java and jena ... 1) I saw this thread and I knew how to use SPARQL with jena (after http)stackoverflow.com/questions/2267333/using-jena-to-create-a-sparql-query-on-dbpedia it did work with me .. but I want my own ontology to work .. I mean to upload it to server or to work on localhost or whatever ... 2) SPARQL doesn't support operations like update or insert .. but querying is there any other languages/methods that support these operations ? or I should created it manually in java in each application ... 3) how can I upload my ontology and I prefer something related to protege ? because I tried this which got bug : (after http )semweb.krasu.ru/protege2joseki/ and this (which gave me lot of issues) (after http and wwwdot)joseki.org/ nothing work .. 4) RDF-store ... is for just RDF ? because I am working on OWL files .. I mean for example using MySQL as RDF-store .. would it work for OWL concept ?

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• ForeignSecurityPrincipals with LDAP connection on Active Directory servers with trusted forest

  - by Killerwhile

  The context is the following : Two domains mutually trusted dc=dom1 dc=dom2 a group cn=group1,ou=someou,dc=dom1 with users inside : cn=user11,ou=anotherou,dc=dom1 cn=user12,ou=anotherou,dc=dom1 cn=user13,ou=anotherou,dc=dom1 cn=user21,ou=anotherou,dc=dom2 cn=user22,ou=anotherou,dc=dom2 cn=user23,ou=anotherou,dc=dom2 The questions : 1. Test user's credentials How can I do a ldap bind to test credentials for users of dom2 ? I tried to bind as usual but I cannot authenticate users of dom2, even if I connect in ldaps. Is there any trick ? Special permissions to set ? 2. Search and display users from the group. How can I retrieve the detailed informations about the users of dom1 and dom2 using LDAP(s) connection on the AD of dom1 ? I have an technical user which has right to browse both domain. I'm able to see 6 entries in the group with the following filter : (&(memberOf=cn=group1,ou=someou,dc=dom1)(|(objectClass=user)(objectClass=foreignSecurityPrincipal))) but the users from the other domain are seen as cn=...(some key)...,cn=foreignSecurityPrincipal,dc=dom1 Java hints would be better. Thanks a lot !

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• ASP.NET: aggregating validators in a user control

  - by orsogufo

  I am developing a web application where I would like to perform a set of validations on a certain field (an account name in the specific case). I need to check that the value is not empty, matches a certain pattern and is not already used. I tried to create a UserControl that aggregates a RequiredFieldValidator, a RegexValidator and a CustomValidator, then I created a ControlToValidate property like this: public partial class AccountNameValidator : System.Web.UI.UserControl { public string ControlToValidate { get { return ViewState["ControlToValidate"] as string; } set { ViewState["ControlToValidate"] = value; AccountNameRequiredFieldValidator.ControlToValidate = value; AccountNameRegexValidator.ControlToValidate = value; AccountNameUniqueValidator.ControlToValidate = value; } } } However, if I insert the control on a page and set ControlToValidate to some control ID, when the page loads I get an error that says Unable to find control id 'AccountName' referenced by the 'ControlToValidate' property of 'AccountNameRequiredFieldValidator', which makes me think that the controls inside my UserControl cannot resolve correctly the controls in the parent page. So, I have two questions: 1) Is it possible to have validator controls inside a UserControl validate a control in the parent page? 2) Is it correct and good practice to "aggregate" multiple validator controls in a UserControl? If not, what is the standard way to proceed?

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• How to compile Python scripts for use in FORTRAN?

  - by Vincent Poirier

  Hello, Although I found many answers and discussions about this question, I am unable to find a solution particular to my situation. Here it is: I have a main program written in FORTRAN. I have been given a set of python scripts that are very useful. My goal is to access these python scripts from my main FORTRAN program. Currently, I simply call the scripts from FORTRAN as such: CALL SYSTEM ('python pyexample.py') Data is read from .dat files and written to .dat files. This is how the python scripts and the main FORTRAN program communicate to each other. I am currently running my code on my local machine. I have python installed with numpy, scipy, etc. My problem: The code needs to run on a remote server. For strictly FORTRAN code, I compile the code locally and send the executable to the server where it waits in a queue. However, the server does not have python installed. The server is being used as a number crunching station between universities and industry. Installing python along with the necessary modules on the server is not an option. This means that my “CALL SYSTEM ('python pyexample.py')” strategy no longer works. Solution?: I found some information on a couple of things in thread http://stackoverflow.com/questions/138521/is-it-feasible-to-compile-python-to-machine-code Shedskin, Psyco, Cython, Pypy, Cpython API These “modules”(? Not sure if that's what to call them) seem to compile python script to C code or C++. Apparently not all python features can be translated to C. As well, some of these appear to be experimental. Is it possible to compile my python scripts with my FORTRAN code? There exists f2py which converts FORTRAN code to python, but it doesn't work the other way around. Any help would be greatly appreciated. Thank you for your time. Vincent PS: I'm using python 2.6 on Ubuntu

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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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• Java design: too many getters

  - by dege

  After writing a few lesser programs when learning Java the way I've designed the programs is with Model-View-Control. With using MVC I have a plethora of getter methods in the model for the view to use. It feels that while I gain on using MVC, for every new value added I have to add two new methods in the model which quickly get all cluttered with getter & setters. So I was thinking, maybe I should use the notifyObserver method that takes an argument. But wouldn't feel very smart to send every value by itself either so I figured, maybe if I send a kind of container with all the values, preferably only those that actually changed. What this would accomplish would be that instead of having a whole lot of getter methods I could just have one method in the model which put all relevant values in the container. Then in the view I would have a method called from the update which extracted the values from the container and assigning them to the correct fields. I have two questions concerning this. First: is this actually a viable way to do this. Would you recommend me doing something along these lines? Secondly: if I do use this plan and I don't want to keep sending fields that didn't actually change. How would I handle that without having to have if statements to check if the value is not null for every single value?

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• how to get cartesian products between database and local sequences in linq?

  - by JD

  I saw this similar question here but can't figure out how to use Contains in Cartesian product desired result situation: http://stackoverflow.com/questions/1712105/linq-to-sql-exception-local-sequence-cannot-be-used-in-linq-to-sql-implementatio Let's say I have following: var a = new [] { 1, 4, 7 }; var b = new [] { 2, 5, 8 }; var test = from i in a from j in b select new { A = i, B = j, AB = string.Format("{0:00}a{1:00}b", i, j), }; foreach (var t in test) Console.Write("{0}, ", t.AB); This works great and I get a dump like so (note, I want the cartesian product): 01a02b, 01a05b, 01a08b, 04a02b, 04a05b, 04a08b, 07a02b, 07a05b, 07a08b, Now what I really want is to take this and cartesian product it again against an ID from a database table I have. But, as soon as I add in one more from clause that instead of referencing objects, references SQL table, I get an error. So, altering above to something like so where db is defined as a new DataContext (i.e., class deriving from System.Data.Linq.DataContext): var a = new [] { 1, 4, 7 }; var b = new [] { 2, 5, 8 }; var test = from symbol in db.Symbols from i in a from j in b select new { A = i, B = j, AB = string.Format("{0}{1:00}a{2:00}b", symbol.ID, i, j), }; foreach (var t in test) Console.Write("{0}, ", t.AB); The error I get is following: Local sequence cannot be used in LINQ to SQL implementations of query operators except the Contains operator Its related to not using Contains apparently but I'm unsure how Contains would be used when I don't really want to constrict the results - I want the Cartesian product for my situation. Any ideas of how to use Contains above and still yield the Cartesian product when joining database and local sequences?

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• When and how should independent hierarchies be used in clojure?

  - by Rob Lachlan

  Clojure's system for creating an ad hoc hierarchy of keywords is familiar to most people who have spent a bit of time with the language. For example, most demos and presentations of the language include examples such as (derive ::child ::parent) and they go on to show how this can be used for multi-method dispatch. In all of the slides and presentations that I've seen, they use the global hierarchy. But it is possible to put keyword relationships in independent hierarchies, by using (derive h ::child ::parent), where h is created by (make-hierarchy). Some questions, therefore: Are there any guidelines on when this is useful or necessary? Are there any functions for manipulating hierarchies? Merging is particularly useful, so I do this: (defn merge-h [& hierarchies] (apply merge-with (cons #(merge-with clojure.set/union %1 %2) hierarchies)) But I was wondering if such functions already exist somewhere. EDIT: Changed "custom" hierarchy to "independent" hierarchy, since that term better describes this animal. Also, I've done some research and included my own answer below. Further comments are welcome.

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• Asymptotic complexity of a compiler

  - by Meinersbur

  What is the maximal acceptable asymptotic runtime of a general-purpose compiler? For clarification: The complexity of compilation process itself, not of the compiled program. Depending on the program size, for instance, the number of source code characters, statements, variables, procedures, basic blocks, intermediate language instructions, assembler instructions, or whatever. This is highly depending on your point of view, so this is a community wiki. See this from the view of someone who writes a compiler. Will the optimisation level -O4 ever be used for larger programs when one of its optimisations takes O(n^6)? Related questions: When is superoptimisation (exponential complexity or even incomputable) acceptable? What is acceptable for JITs? Does it have to be linear? What is the complexity of established compilers? GCC? VC? Intel? Java? C#? Turbo Pascal? LCC? LLVM? (Reference?) If you do not know what asymptotic complexity is: How long are you willing to wait until the compiler compiled your project? (scripting languages excluded)

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• Namespaces combined with TFS / Source Control explanation

  - by Christian

  As an ISV company we slowly run into the "structure your code"-issue. We mainly develop using Visual Studio 2008 and 2010 RC. Languages c# and vb.net. We have our own Team Foundation Server and of course we use Source Control. When we started developing based on the .NET Framework, we also begun using Namespaces in a primitive way. With the time we 'became more mature', i mean we learned to use the namespaces and we structured the code more and more, but only in the solution scope. Now we have about 100 different projects and solutions in our Source Safe. We realized that many of our own classes are coded very redundant, i mean, a Write2Log, GetExtensionFromFilename or similar Function can be found between one and 20 times in all these projects and solutions. So my idea is: Creating one single kind of root folder in Source Control and start an own namespace-hierarchy-structure below this root, let's name it CompanyName. A Write2Log class would then be found in CompanyName.System.Logging. Whenever we create a new solution or project and we need a log function, we will 'namespace' that solution and place it accordingly somewhere below the CompanyName root folder. To have the logging functionality we then import (add) the existing project to the solution. Those 20+ projects/solutions with the write2log class can then be maintained in one single place. To my questions: - is that a good idea, the philosophy of namespaces and source control? - There must be a good book explaining the Namespaces combined with Source Control, yes? any hints/directions/tips? - how do you manage your 50+ projects?

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• Using a .MDF SQL Server Database with ASP.NET Versus Using SQL Server

  - by Maxim Z.

  I'm currently writing a website in ASP.NET MVC, and my database (which doesn't have any data in it yet, it only has the correct tables) uses SQL Server 2008, which I have installed on my development machine. I connect to the database out of my application by using the Server Explorer, followed by LINQ to SQL mapping. Once I finish developing the site, I will move it over to my hosting service, which is a virtual hosting plan. I'm concerned about whether using the SQL Server setup that is currently working on my development machine will be hard to do on the production server, as I'll have to import all the database tables through the hosting control panel. I've noticed that it is possible to create a SQL Server database from inside Visual Studio. It is then stored in the App_Data directory. My questions are the following: Does it make sense to move my SQL Server DB out of SQL Server and into the App_Data directory as an .mdf file? If so, how can I move it? I believe this is called the Detach command, is it not? Are there any performance/security issues that can occur with a .mdf file like this? Would my intended setup work OK with a typical virtual hosting plan? I'm hoping that the .mdf database won't count against the limited number of SQL Server databases that can be created with my plan. I hope this question isn't too broad. Thanks in advance! Note: I'm just starting out with ASP.NET MVC and all this, so I might be completely misunderstanding how this is supposed to work.

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