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  • Change Data Capture or Change Tracking - Same as Traditional Audit Trail Table?

    - by HardCode
    Before I delve into the abyss of Microsoft documentation any deeper, I'd like to know if someone experienced with Change Data Capture and Change Tracking know if one or both of these can be used to replace the traditional ... "Audit trail table copy of the 'real table' (all of the fields of the original table, plus date/time, user ID, and DML action field) inserted into by Triggers" ... setup for a database table audit trail, where the trigger populates the audit trail table (which is all manual work). The MSDN overview documentation explains at a high level what Change Data Capture and Change Tracking are, but it isn't clear enough to me, and doesn't state outright, that these tools can be used to replace the traditional audit trail tables we've made so often. Can someone with any experience using Change Data Capture and Change Tracking save me a lot of time, or confirm that I am spending time looking at the right tool? The critical part of our audit trail is capturing all changes to a table's fields (on INSERT, UPDATE, DELETE), when it happened, and who did it. These changes are commonly provided to an end user chronologically via an audit trail report. Which is another question ... Change Data Capture or Change Tracking is the solution, I'd assume that this data can be queried just like data from a normal table? EDIT: I need a permanent audit trail, irregardless of time. I see that Change Data Capture has to do with the transaction logs, so this sounds finite to me.

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  • How to limit traffic using multicast over localhost

    - by Shane Holloway
    I'm using multicast UDP over localhost to implement a loose collection of cooperative programs running on a single machine. The following code works well on Mac OSX, Windows and linux. The flaw is that the code will receive UDP packets outside of the localhost network as well. For example, sendSock.sendto(pkt, ('192.168.0.25', 1600)) is received by my test machine when sent from another box on my network. import platform, time, socket, select addr = ("239.255.2.9", 1600) sendSock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP) sendSock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 24) sendSock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_IF, socket.inet_aton("127.0.0.1")) recvSock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP) recvSock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, True) if hasattr(socket, 'SO_REUSEPORT'): recvSock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, True) recvSock.bind(("0.0.0.0", addr[1])) status = recvSock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, socket.inet_aton(addr[0]) + socket.inet_aton("127.0.0.1")); while 1: pkt = "Hello host: {1} time: {0}".format(time.ctime(), platform.node()) print "SEND to: {0} data: {1}".format(addr, pkt) r = sendSock.sendto(pkt, addr) while select.select([recvSock], [], [], 0)[0]: data, fromAddr = recvSock.recvfrom(1024) print "RECV from: {0} data: {1}".format(fromAddr, data) time.sleep(2) I've attempted to recvSock.bind(("127.0.0.1", addr[1])), but that prevents the socket from receiving any multicast traffic. Is there a proper way to configure recvSock to only accept multicast packets from the 127/24 network, or do I need to test the address of each received packet?

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  • C++ Newbie: Passing an fstream to a function to read data

    - by vgm64
    I have a text file named num.txt who's only contents is the line 123. Then I have the following: void alt_reader(ifstream &file, char* line){ file.read(line, 3); cout << "First Time: " << line << endl; } int main() { ifstream inFile; int num; inFile.open("num.txt"); alt_reader(inFile, (char*)&num); cout << "Second Time: " << num << endl; } The output is: First Time: 123 Second Time: 3355185 Can you help me figure out how to get an fstream that is read in a function still assign the variable in main? I'm doing this because alt_reader really has a lot more to it, but this is the part I'm stuck on. Thanks a lot for the help.

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  • TDD test data loading methods

    - by Dave Hanson
    I am a TDD newb and I would like to figure out how to test the following code. I am trying to write my tests first, but I am having trouble for creating a test that touches my DataAccessor. I can't figure out how to fake it. I've done the extend the shipment class and override the Load() method; to continue testing the object. I feel as though I end up unit testing my Mock objects/stubs and not my real objects. I thought in TDD the unit tests were supposed to hit ALL of the methods on the object; however I can never seem to test that Load() code only the overriden Mock Load My tests were write an object that contains a list of orders based off of shipment number. I have an object that loads itself from the database. public class Shipment { //member variables protected List<string> _listOfOrders = new List<string>(); protected string _id = "" //public properties public List<string> ListOrders { get{ return _listOfOrders; } } public Shipment(string id) { _id = id; Load(); } //PROBLEM METHOD // whenever I write code that needs this Shipment object, this method tries // to hit the DB and fubars my tests // the only way to get around is to have all my tests run on a fake Shipment object. protected void Load() { _listOfOrders = DataAccessor.GetOrders(_id); } } I create my fake shipment class to test the rest of the classes methods .I can't ever test the Real load method without having an actual DB connection public class FakeShipment : Shipment { protected new void Load() { _listOfOrders = new List<string>(); } } Any thoughts? Please advise. Dave

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  • What vertex shader code should be used for a pixel shader used for simple 2D SpriteBatch drawing in XNA?

    - by Michael
    Preface First of all, why is a vertex shader required for a SilverlightEffect (.slfx file) in Silverlight 5? I'm trying to port a simple 2D XNA game to Silverlight 5 RC, and I would like to use a basic pixel shader. This shader works great in XNA for Windows and Xbox, but I can't get it to compile with Silverlight as a SilverlightEffect. The MS blog for the Silverlight Toolkit says that "there is no difference between .slfx and .fx", but apparently this isn't quite true -- or at least SpriteBatch is working some magic for us in "regular XNA", and it isn't in "Silverlight XNA". If I try to directly copy my pixel shader file into a Silverlight project (and change it to the supported "Effect - Silverlight" importer/processor), when I try to compile I see the following error message: Invalid effect file. Unable to find vertex shader in pass "P0" Indeed, there isn't a vertex shader in my pixel shader file. I haven't needed one with my other 2D XNA apps since I'm just doing basic SpriteBatch drawing. I tried adding a vertex shader to my shader file, using Remi Gillig's comment on this Shawn Hargreaves blog post for guidance, but it doesn't quite work. The shader file successfully compiles, and I see some semblance of my game on screen, but it's tiny, twisted, repeated, and all jumbled up. So clearly something's not quite right. The Real Question So that brings me to my real question: Since a vertex shader is required, is there a basic vertex shader function that works for simple 2D SpriteBatch drawing? And if the vertex shader requires world/view/project matricies as parameters, what values am I supposed to use for a 2D game? Can any shader pros help? Thanks!

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  • Jquery Internet Explorer 8 compatibility issue, does not load data unless history is deleted...

    - by Scarface
    Hey guys, I have a weird problem. I have an update system that refreshes data on a time interval. It works well in all browsers except internet explorer 8. The problem is that once it loads the data, it does not matter if the data updates further, it will not update the data visually until the internet history is cleared. I am not using any cookies server-side...Anyone ever encounter something like this? Here is my javascript, thanks for any assistance in advance function prepare(response) { var d = new Date(); count++; d.setTime(response.time*1000); var mytime = d.getHours()+':'+d.getMinutes()+':'+d.getSeconds(); var string = '<li class="shoutbox-list" id="list-'+count+'">' + '<span class="shoutbox-list-nick"><a href="statistics.php?user='+response.user+'">'+response.user+'</a></span>' + ' <span class="date">'+mytime+'</span><br>' + '<span class="msg">'+response.message+'</span>' +'</li>'; return string; } function refresh() { $.getJSON(files+"shoutbox.php?action=view&time="+lastTime+"&topic_id="+topic_id, function(json) { if(json.length) { for(i=0; i < json.length; i++) { $('#daddy-shoutbox-list').prepend(prepare(json[i])); $('#list-' + count).fadeIn(1500); } var j = i-1; lastTime = json[j].time; } //alert(lastTime); }); timeoutID = setTimeout(refresh, 3000); } $(document).ready(function() { var options = { dataType: 'json', beforeSubmit: validate, success: function(response, status){ if (response.error=='success'){ success(response, status); } else { $.prompt(response.error); } } }; $('#daddy-shoutbox-form').ajaxForm(options); timeoutID = setTimeout(refresh, 100); });

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  • PHP Performance Metrics

    - by bigstylee
    I am currently developing a PHP MVC Framework for a personal project. While I am developing the framework I am interested to see any notable performance by implementing different techniques for optimization. I have implemented a crude BenchMark class that logs mircotime. The problem is I have no frame of reference for execution times. I am very near the beginnig of this project with a database connection and a few queries but no output (bar some debugging text and BenchMark log). I have a current execution time of 0.01917 seconds. I was expecting this to be lower but as I said before I have no frame of reference. I appreciate there are many variables to take into account when juding performance but I am hoping to find some sort of metric to a) techniques to measure performance for example requests per second and b) compare results for example; how a "moderately" sized PHP application on a "standard" webserver will perform. I appreciate "moderately" and "standard" are very subjective words so perhaps a table of known execution times for a particular application (eg StackOverFlow's executing time). What are other techniques of measuring performance are there other than execution time? When looking at MVC Framework Performance Comparisom it talks about Requests Per Second (RPS). How is this calculated? I am guessing with my current execution time of 0.01917 seconds can handle 52 RPS (= 1 / 0.01917 ). This seems to be significantly lower than that quoted on the graph especially when you consider my current limited funcitonality.

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  • Why does the page posts take so long?

    - by Olle
    Hi! I am having some problems with some page post backs that take a loooong time to execute. If I do a "appcmd list requests" I can get something like this: REQUEST "79000001800004e3" (url:POST /dir/file.aspx, time:87219 msec, client:xxx.xxx.xxx.xxx, stage:ExecuteRequestHandler, module:ManagedPipelineHandler) REQUEST "8600000080002f82" (url:POST /dir/file.aspx, time:61391 msec, client:xxx.xxx.xxx.xxx, stage:AcquireRequestState, module:Session) REQUEST "5e00010280000420" (url:POST /dir/file.aspx, time:21047 msec, client:xxx.xxx.xxx.xxx, stage:AcquireRequestState, module:Session) It's one particular file that causes the problem (dir/file.aspx in this case). It comes from the same IP-adress. And the first on is from ManagedPipelineHandler module and the two after that from Session module. I do not have any details about the web browser, or anything more about the client for that matter. I have looked for sql dead locks and did not find any. There are no long running sql queries at all. Do you have any idea of what can be the problem? Regards.

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  • How do I avoid repetition in Java ResourceBundle strings?

    - by Trejkaz
    We had a lot of strings which contained the same sub-string, from sentences about checking the log or how to contact support, to branding-like strings containing the company or product name. The repetition was causing a few issues for ourselves (primarily typos or copy/paste errors) but it also causes issues in that it increases the amount of text our translator has to translate. The solution I came up with went something like this: public class ExpandingResourceBundleControl extends ResourceBundle.Control { public static final ResourceBundle.Control EXPANDING = new ExpandingResourceBundleControl(); private ExpandingResourceBundleControl() { } @Override public ResourceBundle newBundle(String baseName, Locale locale, String format, ClassLoader loader, boolean reload) throws IllegalAccessException, InstantiationException, IOException { ResourceBundle inner = super.newBundle(baseName, locale, format, loader, reload); return inner == null ? null : new ExpandingResourceBundle(inner, loader); } } ExpandingResourceBundle delegates to the real resource bundle but performs conversion of {{this.kind.of.thing}} to look up the key in the resources. Every time you want to get one of these, you have to go: ResourceBundle.getBundle("com/acme/app/Bundle", EXPANDING); And this works fine -- for a while. What eventually happens is that some new code (in our case autogenerated code which was spat out of Matisse) looks up the same resource bundle without specifying the custom control. This appears to be non-reproducible if you write a simple unit test which calls it with and then without, but it occurs when the application is run for real. Somehow the cache inside ResourceBundle ejects the good value and replaces it with the broken one. I am yet to figure out why and Sun's jar files were compiled without debug info so debugging it is a chore. My questions: Is there some way of globally setting the default ResourceBundle.Control that I might not be aware of? That would solve everything rather elegantly. Is there some other way of handling this kind of thing elegantly, perhaps without tampering with the ResourceBundle classes at all?

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  • Counter that will remember it's value

    - by owca
    I have a task to operate on complex number. Each number consists of double r = real part, double i = imaginary part and String name. Name must be set within constructor, so I've created int counter, then I'm sending it's value to setNextName function and get name letter back. Unfortunately incrementing this 'counter' value works only within costructor and then it is once again set to 0. How to deal with that?Some constant value? And second problem is that I also need to provide setNextNames(char c) function that will change the counter current value. The code : public class Imaginary { private double re; private double im; private String real; private String imaginary; private String name; private int counter=0; public Imaginary(double r, double u){ re = r; im = u; name = this.setNextName(counter); counter++; } public static String setNextName(int c){ String nameTab[] = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N", "O","P","Q","R","S","T","U","W","V","X","Y","Z"}; String setName = nameTab[c]; System.out.println("c: "+c); return setName; } public static String setNextName(char c){ // //don't know how to deal with this part // }

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  • How to write C++ audio processing applications?

    - by cesko82
    Hi everyone, I'm an Electronics and Telecommunications student, next to my graduation. I'm gonna work on a project that involves my knowledge about DSP, music and audio in general. I allready know all the basic mathematic instruments and all the stuff I need to manage it, such as FFT, circular convolution ecc ecc. I want to learn C++ programming basically for one reason: it's very important in the professional world!!! And I think it's one of the most used to write applications working with audio, especially when it's about real time processing. Ok, after this small introduction I would like to know first, which are the most used libraries to work with audio processing in c++?? I was longer looking on the web but i couldn't find a lo of working stuff. (I work under linux with eclipse CDT enviroment). Then I would like to know if there are good sources to learn how to write some working code, such as for example how to write a simple low pass filter. Basically now i will not write real time applications, I would like to start from the processing of a WAV file, or even better an MP3 file, so basically on vectors of samples. Let's say that basically for now I would like to extract the waveform from an audio file, and save it to a thumbnail or to a PNG image. Ok, for now I think it's all I would need. Any ideas, advices, libraries, books, interesting sources about that? Thanks a lot in advance for any kind of answer. Giovanni.

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  • Why doesn't Perl file glob() work outside of a loop in scalar context?

    - by Rob
    According to the Perl documentation on file globbing, the <*> operator or glob() function, when used in a scalar context, should iterate through the list of files matching the specified pattern, returning the next file name each time it is called or undef when there are no more files. But, the iterating process only seems to work from within a loop. If it isn't in a loop, then it seems to start over immediately before all values have been read. From the Perl docs: In scalar context, glob iterates through such filename expansions, returning undef when the list is exhausted. http://perldoc.perl.org/functions/glob.html However, in scalar context the operator returns the next value each time it's called, or undef when the list has run out. http://perldoc.perl.org/perlop.html#I/O-Operators Example code: use warnings; use strict; my $filename; # in scalar context, <*> should return the next file name # each time it is called or undef when the list has run out $filename = <*>; print "$filename\n"; $filename = <*>; # doesn't work as documented, starts over and print "$filename\n"; # always returns the same file name $filename = <*>; print "$filename\n"; print "\n"; print "$filename\n" while $filename = <*>; # works in a loop, returns next file # each time it is called In a directory with 3 files...file1.txt, file2.txt, and file3.txt, the above code will output: file1.txt file1.txt file1.txt file1.txt file2.txt file3.txt Note: The actual perl script should be outside the test directory, or you will see the file name of the script in the output as well. Am I doing something wrong here, or is this how it is supposed to work?

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  • Neural Network settings for fast training

    - by danpalmer
    I am creating a tool for predicting the time and cost of software projects based on past data. The tool uses a neural network to do this and so far, the results are promising, but I think I can do a lot more optimisation just by changing the properties of the network. There don't seem to be any rules or even many best-practices when it comes to these settings so if anyone with experience could help me I would greatly appreciate it. The input data is made up of a series of integers that could go up as high as the user wants to go, but most will be under 100,000 I would have thought. Some will be as low as 1. They are details like number of people on a project and the cost of a project, as well as details about database entities and use cases. There are 10 inputs in total and 2 outputs (the time and cost). I am using Resilient Propagation to train the network. Currently it has: 10 input nodes, 1 hidden layer with 5 nodes and 2 output nodes. I am training to get under a 5% error rate. The algorithm must run on a webserver so I have put in a measure to stop training when it looks like it isn't going anywhere. This is set to 10,000 training iterations. Currently, when I try to train it with some data that is a bit varied, but well within the limits of what we expect users to put into it, it takes a long time to train, hitting the 10,000 iteration limit over and over again. This is the first time I have used a neural network and I don't really know what to expect. If you could give me some hints on what sort of settings I should be using for the network and for the iteration limit I would greatly appreciate it. Thank you!

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  • How can I test this SQL Server performance Utility?

    - by Martin Smith
    As part of my MSc I need to do a three month project later this year. I have decided to do something which will likely be useful for me in the workplace and spend the time getting to understand SQL Server internals. The deliverable for this project will be a performance advisor looking at a variety of different rules. Some static such as finding redundant indexes, some more dynamic such as using XEvents to find outlying invocations of stored procedure execution times when certain parameters are passed. I am struggling to come up with a good way of testing this though. I can obviously design a "bad" database and a synthetic workload that my tool will pick up issues on but I also need to demonstrate that it has real world utility. Looking at the self tuning database literature it is common to use TPC benchmarks but I've had a look at the TPCC site and it looks very time consuming to implement and not that good a fit to my project's testing needs in any event (I would still be able to "rig" it by the decisions I made on indexing or physical architecture). Plan A would be to find willing beta tester(s) but in the event that isn't possible I will need a fallback plan. The best idea I have come up with so far is to use the various MS sample applications as examples of real world applications. e.g. http://msftdpprodsamples.codeplex.com/ http://www.asp.net/community/projects/ Does anyone have any better suggestions?

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  • Why do I have to unserialize this serialized value twice?

    - by 55skidoo
    What am I doing wrong here? I'm serializing a value, storing it in a database (table bb_meta), retrieving it... OK so far... but then I have to unserialize it twice. Shouldn't I be able to just unserialize once? This seems to work, but I'm wondering what point about serialization I'm missing here. //check database to see if user has ever visited before. $querystring = $bbdb->prepare( "SELECT `meta_value` FROM `$bbdb->meta` WHERE `object_type` = %s AND `object_id` = %s AND `meta_key` = %s LIMIT 1", $bbtype, $bb_this_thread, $bbuser ); $bb_last_visits = $bbdb->get_row($querystring, OBJECT); //if $bb_last_visits is empty, add time() as the metavalue using bb_update_meta if (empty($bb_last_visits)) { $first_visit = time(); echo 'serialized first visit: ' . $bb_this_visit_time_serialized = serialize(array($bb_this_thread => $first_visit)); bb_update_meta( $bb_this_thread, $bbuser, $bb_this_visit_time_serialized, $bbtype ); //add to database, bb_meta table echo '$bb_last_visits was empty. Setting first visit time as ' . $bb_this_visit_time_serialized . '<br>'; } else { //else, test by unserializing the data for use. echo 'last visit time already set: '; echo $bb_last_visits->meta_value; echo '<br>'; //fatal error - echo 'unserialized: ' . $bb_last_visits_unserialized = unserialize($bb_last_visits[0]->meta_value); echo '<br>'; echo 'unserialize: ' . $unserialized_visits = unserialize($bb_last_visits->meta_value); echo '<br>'; echo 'hmm, need to unserialize again??: '; echo $unserialized_unserialized_visits = unserialize($unserialized_visits); echo '<br>'; echo 'hey look, it\'s an array value I can finally use now. phew: ' . $unserialized_unserialized_visits[$bb_this_thread]; }

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  • How to arrange business logic in a Kohana 3 project

    - by Pekka
    I'm looking for advice, tutorials and links at how to set up a mid-sized web application with Kohana 3. I have implemented MVC patterns in the past but never worked against a "formalized" MVC framework so I'm still getting my head around the terminology - toying around with basic examples, building views and templates, and so on. I'm progressing fairly well but I want to set up a real-world web project (one of my own that I've been planning for quite some time now) as a learning object. I learn best by example, but example-based documentation is a bit sparse for Kohana 3 right now - they say so themselves on the site. While I'm not worried about learning the framework as I go along, I want to make sure the code base is healthily structured from the start - i.e. controllers are split nicely, named well and according to standards, and most importantly the business logic is separated into appropriately sized models. My application could, in its core, be described as a business directory with a range of search and listing functions, and a login area for each entry owner. The actual administrative database backend is already taken care of. Supposing I have all the API worked out and in place already - list all businesses, edit business, list businesses by street name, create offer logged in as business, and so on, and I'm just looking for how to fit the functionality into a MVC pattern and into a Kohana application structure that can be easily extended. Do you know real-life examples of "database-heavy" applications like directories, online communities... with a log-in area built on Kohana 3, preferably Open Source so I could take a peek how they do it? Are there conventions or best practices on how to structure an extendable login area for end users in a Kohana project that is not only able to handle a business directory page, but further products on separate pages as well? Do you know any good resources on building complex applications with Kohana? Have you built something similar and could give me recommendations on a project structure?

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  • a selector which has this selector together with a class selector

    - by Woho87
    Here is an analogy of my problem(a selector which has this selector together with a class selector): Let say that I selects all yellow(classes) div elements in a arbitrary HTML document. And I want each to check if the attribute is yes = 1. If the attribute 'yes' equals '1', then I want the child with class 'blue' have the attribute 'no' equals '1'; $('div .yellow').each(function(){ if($(this).attr('yes') == 1){ $(this '.blue:first-child').attr('no', 1);//This line needs to be fixed } }); I know that the line this.getElementsByClassName('blue')[0] fixes this problem. But in my real problem (not this analogy) I want to use addClass and removeClass which only functions with jQuery objects. It is to cumbersome to use other functions than addClass and removeClass. UPDATE: Here is a code snippet from my real problem. I got some problem with "this" in javascript. I want a invited button to have the className visible when I click on it. The button lies within a div element with className 'box'. I know that there are problem with 'this' on the code snippet. But I want the button and not the box to change to visible $('.Box').each(function(){ if($(this).attr('hasButton') != 1){ var invite = document.createElement('div'); invite.className = 'invite invisible'; invite.innerHTML = 'invite'; $(this).attr('hasButton', 1); this.appendChild(invite); invite.addEventListener('mouseover', function(event){ $('.invite', this).removeClass('invisible');//this line is not functioning $('.invite', this).addClass('visible');//neither this }, false); } });

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  • F# passing an operator with arguments to a function

    - by dan
    Can you pass in an operation like "divide by 2" or "subtract 1" using just a partially applied operator, where "add 1" looks like this: List.map ((+) 1) [1..5];; //equals [2..6] // instead of having to write: List.map (fun x-> x+1) [1..5] What's happening is 1 is being applied to (+) as it's first argument, and the list item is being applied as the second argument. For addition and multiplication, this argument ordering doesn't matter. Suppose I want to subtract 1 from every element (this will probably be a common beginners mistake): List.map ((-) 1) [1..5];; //equals [0 .. -4], the opposite of what we wanted 1 is applied to the (-) as its first argument, so instead of (list_item - 1), I get (1 - list_item). I can rewrite it as adding negative one instead of subtracting positive one: List.map ((+) -1) [1..5];; List.map (fun x -> x-1) [1..5];; // this works too I'm looking for a more expressive way to write it, something like ((-) _ 1), where _ denotes a placeholder, like in the Arc language. This would cause 1 to be the second argument to -, so in List.map, it would evaluate to list_item - 1. So if you wanted to map divide by 2 to the list, you could write: List.map ((/) _ 2) [2;4;6] //not real syntax, but would equal [1;2;3] List.map (fun x -> x/2) [2;4;6] //real syntax equivalent of the above Can this be done or do I have to use (fun x -> x/2)? It seems that the closest we can get to the placeholder syntax is to use a lambda with a named argument.

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  • Bored with CS. What can I study that will make an impact?

    - by Eric Martinez
    So I'm going to an average university, majoring in CS. I haven't learned a damn thing and am in my third year. I've come to be really bored with studying CS. Initially, I was kind of misinformed and thought majoring in CS would make me a good "product creator". I make my money combining programming and business/marketing. But I have always done programming for the love of the art. I find things like algorithms interesting and want to be able to use CS to solve real world problems. I like the idea of bioinformatics and other hybrid studies. I'm not good enough, yet I hope, to really make a significant effort in those areas but I aspire to be. What are some other fields, open problems, and otherwise cool stuff to apply CS knowledge to in the real world? I'm really looking for something that will motivate me and re-excite me to continue studying CS. Edit: Like someone mentioned below. I am very interesting in the idea of being able to use computer science to help answer fundamental questions of life and the universe. But I'm not sure what is possible or how to begin.

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  • PHP jQuery Long Polling Chat Application

    - by Tejas Jadhav
    I've made a simple PHP jQuery Chat Application with Short Polling (AJAX Refresh). Like, every 2 - 3 seconds it asks for new messages. But, I read that Long Polling is a better approach for Chat applications. So, I went through some Long Polling scripts. I made like this: Javascript: $("#submit").click(function(){ $.ajax({ url: 'chat-handler.php', dataType: 'json', data: {action : 'read', message : 'message'} }); }); var getNewMessage = function() { $.ajax({ url: 'chat-handler.php', dataType: 'json', data: {action : 'read', message : 'message'}, function(data){ alert(data); } }); getNewMessage(); } $(document).ready(getNewMessage); PHP <?php $time = time(); while ((time() - $time) < 25) { $data = $db->getNewMessage (); if (!empty ($data)) { echo json_encode ($data); break; } usleep(1000000); // 1 Second } ?> The problem is, once getNewMessage() starts, it executes unless it gets some response (from chat-handler.php). It executes recursively. But if someone wants to send a message in between, then actually that function ($("#submit").click()) never executes as getNewMessage() is still executing. So is there any workaround?

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  • Why do I have to unserialize this serialized value twice? (wordpress/bbpress maybe_serialize)

    - by 55skidoo
    What am I doing wrong here? I'm serializing a value, storing it in a database (table bb_meta), retrieving it... OK so far... but then I have to unserialize it twice. Shouldn't I be able to just unserialize once? This seems to work, but I'm wondering what point about serialization I'm missing here. //check database to see if user has ever visited before. $querystring = $bbdb->prepare( "SELECT `meta_value` FROM `$bbdb->meta` WHERE `object_type` = %s AND `object_id` = %s AND `meta_key` = %s LIMIT 1", $bbtype, $bb_this_thread, $bbuser ); $bb_last_visits = $bbdb->get_row($querystring, OBJECT); //if $bb_last_visits is empty, add time() as the metavalue using bb_update_meta if (empty($bb_last_visits)) { $first_visit = time(); echo 'serialized first visit: ' . $bb_this_visit_time_serialized = serialize(array($bb_this_thread => $first_visit)); bb_update_meta( $bb_this_thread, $bbuser, $bb_this_visit_time_serialized, $bbtype ); //add to database, bb_meta table echo '$bb_last_visits was empty. Setting first visit time as ' . $bb_this_visit_time_serialized . '<br>'; } else { //else, test by unserializing the data for use. echo 'last visit time already set: '; echo $bb_last_visits->meta_value; echo '<br>'; //fatal error - echo 'unserialized: ' . $bb_last_visits_unserialized = unserialize($bb_last_visits[0]->meta_value); echo '<br>'; echo 'unserialize: ' . $unserialized_visits = unserialize($bb_last_visits->meta_value); echo '<br>'; echo 'hmm, need to unserialize again??: '; echo $unserialized_unserialized_visits = unserialize($unserialized_visits); echo '<br>'; echo 'hey look, it\'s an array value I can finally use now. phew: ' . $unserialized_unserialized_visits[$bb_this_thread]; }

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  • Python MD5 Hash Faster Calculation

    - by balgan
    Hi everyone. I will try my best to explain my problem and my line of thought on how I think I can solve it. I use this code for root, dirs, files in os.walk(downloaddir): for infile in files: f = open(os.path.join(root,infile),'rb') filehash = hashlib.md5() while True: data = f.read(10240) if len(data) == 0: break filehash.update(data) print "FILENAME: " , infile print "FILE HASH: " , filehash.hexdigest() and using start = time.time() elapsed = time.time() - start I measure how long it takes to calculate an hash. Pointing my code to a file with 653megs this is the result: root@Mars:/home/tiago# python algorithm-timer.py FILENAME: freebsd.iso FILE HASH: ace0afedfa7c6e0ad12c77b6652b02ab 12.624 root@Mars:/home/tiago# python algorithm-timer.py FILENAME: freebsd.iso FILE HASH: ace0afedfa7c6e0ad12c77b6652b02ab 12.373 root@Mars:/home/tiago# python algorithm-timer.py FILENAME: freebsd.iso FILE HASH: ace0afedfa7c6e0ad12c77b6652b02ab 12.540 Ok now 12 seconds +- on a 653mb file, my problem is I intend to use this code on a program that will run through multiple files, some of them might be 4/5/6Gb and it will take wayy longer to calculate. What am wondering is if there is a faster way for me to calculate the hash of the file? Maybe by doing some multithreading? I used a another script to check the use of the CPU second by second and I see that my code is only using 1 out of my 2 CPUs and only at 25% max, any way I can change this? Thank you all in advance for the given help.

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  • Rot13 for numbers.

    - by dreeves
    EDIT: Now a Major Motion Blog Post at http://messymatters.com/sealedbids The idea of rot13 is to obscure text, for example to prevent spoilers. It's not meant to be cryptographically secure but to simply make sure that only people who are sure they want to read it will read it. I'd like to do something similar for numbers, for an application involving sealed bids. Roughly I want to send someone my number and trust them to pick their own number, uninfluenced by mine, but then they should be able to reveal mine (purely client-side) when they're ready. They should not require further input from me or any third party. (Added: Note the assumption that the recipient is being trusted not to cheat.) It's not as simple as rot13 because certain numbers, like 1 and 2, will recur often enough that you might remember that, say, 34.2 is really 1. Here's what I'm looking for specifically: A function seal() that maps a real number to a real number (or a string). It should not be deterministic -- seal(7) should not map to the same thing every time. But the corresponding function unseal() should be deterministic -- unseal(seal(x)) should equal x for all x. I don't want seal or unseal to call any webservices or even get the system time (because I don't want to assume synchronized clocks). (Added: It's fine to assume that all bids will be less than some maximum, known to everyone, say a million.) Sanity check: > seal(7) 482.2382 # some random-seeming number or string. > seal(7) 71.9217 # a completely different random-seeming number or string. > unseal(seal(7)) 7 # we always recover the original number by unsealing.

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  • Dropping all user tables/sequences in Oracle

    - by Ambience
    As part of our build process and evolving database, I'm trying to create a script which will remove all of the tables and sequences for a user. I don't want to do recreate the user as this will require more permissions than allowed. My script creates a procedure to drop the tables/sequences, executes the procedure, and then drops the procedure. I'm executing the file from sqlplus: drop.sql: create or replace procedure drop_all_cdi_tables is cur integer; begin cur:= dbms_sql.OPEN_CURSOR(); for t in (select table_name from user_tables) loop execute immediate 'drop table ' ||t.table_name|| ' cascade constraints'; end loop; dbms_sql.close_cursor(cur); cur:= dbms_sql.OPEN_CURSOR(); for t in (select sequence_name from user_sequences) loop execute immediate 'drop sequence ' ||t.sequence_name; end loop; dbms_sql.close_cursor(cur); end; / execute drop_all_cdi_tables; / drop procedure drop_all_cdi_tables; / Unfortunately, dropping the procedure causes a problem. There seems to cause a race condition and the procedure is dropped before it executes. E.g.: SQL*Plus: Release 11.1.0.7.0 - Production on Tue Mar 30 18:45:42 2010 Copyright (c) 1982, 2008, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options Procedure created. PL/SQL procedure successfully completed. Procedure created. Procedure dropped. drop procedure drop_all_user_tables * ERROR at line 1: ORA-04043: object DROP_ALL_USER_TABLES does not exist SQL Disconnected from Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64 With the Partitioning, OLAP, Data Mining and Real Application Testing options Any ideas on how to get this working?

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  • How Search Engine Bots Crawl Forums?

    - by Waleed Eissa
    If I have a forums site with a large number of threads, will the search engine bot crawl the whole site every time? Say I have over 1,000,000 threads in my site, will they get crawled every time the bot crawls my site? or how does it work? I want my website to be indexed but I don't want the bot to kill my website! In other words I don't want the bot to keep crawling the old threads again and again every time it crawls my website. Also, what about the pages crawled before? Will the bot request them every time it crawls my website to make sure they are still on the site? I'm asking this because I only link to the latest threads, i.e. there's a page that contains a list of all the latest threads, but I don't link to the older threads, they have to be explicitly requested by URL, e.g. http://www.mysite.com/showthread.aspx?threadid=7 , will this work to stop the bot from bringing my site down and consuming all my bandwidth? P.S. The site is still under development but I want to know in order to design the site so that search engine bots don't bring it down. Thanks

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