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  • What is the best way using multiple lines of <% %> Tag or <% %> Tag with multiple lines?

    - by Salil
    Sorry if the title is not enough to understand what i am asking about. I am rails developer and i used multiple lines of <% % in my views but now i realized that it's not best practice so i came here and like to you all excellent guys what is the correct way in ROR? For example if i required to something like following <% user =User.all %> <% name= [] %> <% count = 0 %> <% for user in users %> <% name << user.name %> <% count+=1%> <% end %> Can i do it as follows ? <% user =User.all name= [] count = 0 for user in users name << user.name count+=1 end %> I know better way of collecting element from array But above is just example. But my question is, is it possible and if yes which is the correct way?

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  • Multi-Column Join in Hibernate/JPA Annotations

    - by bowsie
    I have two entities which I would like to join through multiple columns. These columns are shared by an @Embeddable object that is shared by both entities. In the example below, Foo can have only one Bar but Bar can have multiple Foos (where AnEmbeddableObject is a unique key for Bar). Here is an example: @Entity @Table(name = "foo") public class Foo { @Id @Column(name = "id") @GeneratedValue(generator = "seqGen") @SequenceGenerator(name = "seqGen", sequenceName = "FOO_ID_SEQ", allocationSize = 1) private Long id; @Embedded private AnEmbeddableObject anEmbeddableObject; @ManyToOne(targetEntity = Bar.class, fetch = FetchType.LAZY) @JoinColumns( { @JoinColumn(name = "column_1", referencedColumnName = "column_1"), @JoinColumn(name = "column_2", referencedColumnName = "column_2"), @JoinColumn(name = "column_3", referencedColumnName = "column_3"), @JoinColumn(name = "column_4", referencedColumnName = "column_4") }) private Bar bar; // ... rest of class } And the Bar class: @Entity @Table(name = "bar") public class Bar { @Id @Column(name = "id") @GeneratedValue(generator = "seqGen") @SequenceGenerator(name = "seqGen", sequenceName = "BAR_ID_SEQ", allocationSize = 1) private Long id; @Embedded private AnEmbeddableObject anEmbeddableObject; // ... rest of class } Finally the AnEmbeddedObject class: @Embeddable public class AnEmbeddedObject { @Column(name = "column_1") private Long column1; @Column(name = "column_2") private Long column2; @Column(name = "column_3") private Long column3; @Column(name = "column_4") private Long column4; // ... rest of class } Obviously the schema is poorly normalised, it is a restriction that AnEmbeddedObject's fields are repeated in each table. The problem I have is that I receive this error when I try to start up Hibernate: org.hibernate.AnnotationException: referencedColumnNames(column_1, column_2, column_3, column_4) of Foo.bar referencing Bar not mapped to a single property I have tried marking the JoinColumns are not insertable and updatable, but with no luck. Is there a way to express this with Hibernate/JPA annotations? Thank you.

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  • How good is the memory mapped Circular Buffer on Wikipedia?

    - by abroun
    I'm trying to implement a circular buffer in C, and have come across this example on Wikipedia. It looks as if it would provide a really nice interface for anyone reading from the buffer, as reads which wrap around from the end to the beginning of the buffer are handled automatically. So all reads are contiguous. However, I'm a bit unsure about using it straight away as I don't really have much experience with memory mapping or virtual memory and I'm not sure that I fully understand what it's doing. What I think I understand is that it's mapping a shared memory file the size of the buffer into memory twice. Then, whenever data is written into the buffer it appears in memory in 2 places at once. This allows all reads to be contiguous. What would be really great is if someone with more experience of POSIX memory mapping could have a quick look at the code and tell me if the underlying mechanism used is really that efficient. Am I right in thinking for example that the file in /dev/shm used for the shared memory always stays in RAM or could it get written to the hard drive (performance hit) at some point? Are there any gotchas I should be aware of? As it stands, I'm probably going to use a simpler method for my current project, but it'd be good to understand this to have it in my toolbox for the future. Thanks in advance for your time.

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  • Forum achievements on a phpBB3 board?

    - by VIVA LA NWO
    I recently started a new community. The forum software is phpBB3, and so far so good. In an attempt to make my community more unique and interesting, I had to idea of having user achievements. Let me give you a quick run-down. Each user has achievements that they can earn (these will probably be across all users), for example an achievement for when a user hits 1,000 posts, when they upload an avatar, when one of their topics gets 1,000 views and so on. Each achievement has points, for example an achievement like uploading an avatar will be 10 points and reaching 10,000 points will grant 50 achievement points. If anyone here plays World of Warcraft you may be seeing where I'm getting the ideas from. :) What I'm struggling to get my head around though is how exactly to code this... I could keep a record of all users activity and add it to a special database table possibly, and then check via cron every minute or so if any user has met achievement criteria... but then I also want it controllable through the ACP so I can easily add new achievements and change their points etc. My mind is pretty blank when it comes to anything but the most simple things. What I really posted here for was feedback on the idea and how you all think I should go about doing this. The coding part should be pretty simple for me once I get my head around how phpBBB MODs need to be written. Thanks for reading, and I look forward to your replies. :)

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  • Self referencing update SQL statement for Informix

    - by CheeseConQueso
    Need some Informix SQL... Courses get a regular grade, but their associated labs get a grade of 'LAB'. I need to update the table so that the lab grade matches the course grade. Also, if there is no corresponding course for a lab, it means the course was canceled. In that case, I want to place a flag value of 'X' for its grade. Example data before update: id yr sess crs_no hrs grd 725 2009 FA COLL101 3.000000000000 C 725 2009 FA ENGL021 3.000000000000 FI 725 2009 FA ENGL021L 1.000000000000 LAB 725 2009 FA ENGL031 3.000000000000 FNI 725 2009 FA ENGL031L 1.000000000000 LAB 725 2009 FA MATH010 3.000000000000 FNI 725 2010 SP AOTE101 3.000000000000 C 725 2010 SP ENGL021L 1.000000000000 LAB 725 2010 SP ENGL031 3.000000000000 FI 725 2010 SP ENGL031L 1.000000000000 LAB 725 2010 SP MATH010 3.000000000000 FNI 726 2010 SP SPAN101 3.000000000000 FN Example data after update: id yr sess crs_no hrs grd 725 2009 FA COLL101 3.000000000000 C 725 2009 FA ENGL021 3.000000000000 FI 725 2009 FA ENGL021L 1.000000000000 FI 725 2009 FA ENGL031 3.000000000000 FNI 725 2009 FA ENGL031L 1.000000000000 FNI 725 2009 FA MATH010 3.000000000000 FNI 725 2010 SP AOTE101 3.000000000000 C 725 2010 SP ENGL021L 1.000000000000 X 725 2010 SP ENGL031 3.000000000000 FI 725 2010 SP ENGL031L 1.000000000000 FI 725 2010 SP MATH010 3.000000000000 FNI 726 2010 SP SPAN101 3.000000000000 FN I worked out a solution for this, but it required a lot of on-the-fly composite foreign keys built from concatenating the id, yr, sess, and substring'd crs_no. My solution is not only overkill, but it has gaps in it and it takes too long to process. I know there is an easier way to do this, but I've gone so far down one road that I am having trouble thinking of a different approach.

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  • How do I perform a flip and grow animation like in iPhoto 09?

    - by Austin
    I'm developing a Cocoa application and want to be able to click a button in one of the views in my NSCollectionView and have a details view flip open and position to the middle of the screen like it does in iPhoto 09 when you click the "i" in the bottom-right hand corner of a photo. The photo "flips" and grows, centered on the window to reveal details about the photo. I'm guessing they're using Core Animation to achieve this. I've been looking at the Lemur Flip example, but when I try to modify it to add repositioning code to the animation, it throws off the flip. Here is the positioning code I've added to the - (IBAction)flip:(id)sender; code of LemurFlip: ... [CATransaction begin]; { NSSize supersize = contentView.frame.size; // Size of window content view NSSize subsize = frontView.frame.size; // Size of view we're flipping out if(!frontView.isHidden) { // Move views to middle of the window [[backView animator] setFrameOrigin:NSMakePoint((supersize.width / 2) - (subsize.width / 2), (supersize.height / 2) - (subsize.height / 2))]; [[frontView animator] setFrameOrigin:NSMakePoint((supersize.width / 2) - (subsize.width / 2), (supersize.height / 2) - (subsize.height / 2))]; } else { // Return views to point of origin [[backView animator] setFrameOrigin:NSMakePoint(0, 0)]; [[frontView animator] setFrameOrigin:NSMakePoint(0, 0)]; } [hiddenLayer addAnimation:[self _flipAnimationWithDuration:flipDuration isFront:NO] forKey:@"flipGroup"]; [visibleLayer addAnimation:[self _flipAnimationWithDuration:flipDuration isFront:YES] forKey:@"flipGroup"]; } [CATransaction commit]; ... Is there a good example of how to do this or some rules for combining these sort of animations?

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  • How does DateTime.Now affect query plan caching in SQL Server?

    - by Bill Paetzke
    Question: Does passing DateTime.Now as a parameter to a proc prevent SQL Server from caching the query plan? If so, then is the web app missing out on huge performance gains? Possible Solution: I thought DateTime.Today.AddDays(1) would be a possible solution. It would pass the same end-date to the sql proc (per day). And the user would still get the latest data. Please speak to this as well. Given Example: Let's say we have a stored procedure. It reports data back to a user on a webpage. The user can set a date range. If the user sets today's date as the "end date," which includes today's data, the web app passes DateTime.Now to the sql proc. Let's say that one user runs a report--5/1/2010 to now--over and over several times. On the webpage, the user sees 5/1/2010 to 5/4/2010. But the web app passes DateTime.Now to the sql proc as the end date. So, the end date in the proc will always be different, although the user is querying a similar date range. Assume the number of records in the table and number of users are large. So any performance gains matter. Hence the importance of the question. Example proc and execution (if that helps to understand): CREATE PROCEDURE GetFooData @StartDate datetime @EndDate datetime AS SELECT * FROM Foo WHERE LogDate >= @StartDate AND LogDate < @EndDate Here's a sample execution using DateTime.Now: EXEC GetFooData '2010-05-01', '2010-05-04 15:41:27' -- passed in DateTime.Now Here's a sample execution using DateTime.Today.AddDays(1) EXEC GetFooData '2010-05-01', '2010-05-05' -- passed in DateTime.Today.AddDays(1) The same data is returned for both procs, since the current time is: 2010-05-04 15:41:27.

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  • C# web service, MySql encoding problem

    - by Boban
    I use C# web service to insert, delete and get data from MySql database. The problem is some of the data is in Macedonian (Cyrilic). When I insert directly in the database, it inserts ok. For example: "???" is "???". When I insert throgh the service, it's not. For example: "???" is "???". When I try to get data throug the service, it gets it ok. What's the problem with the inserting? Here is part of my code for inserting: MySqlConnection connection = new MySqlConnection(MyConString); MySqlCommand command = connection.CreateCommand(); command.CommandText = "INSERT INTO user (id_user, name VALUES (NULL, ?name);"; command.Parameters.Add("?name", MySqlDbType.VarChar).Value = name; connection.Open(); command.ExecuteReader(); connection.Close(); return thisrow; Tnq U in advance!!!

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  • Managing inverse relationships without CoreData

    - by Nathaniel Martin
    This is a question for Objective-J/Cappuccino, but I added the cocoa tag since the frameworks are so similar. One of the downsides of Cappuccino is that CoreData hasn't been ported over yet, so you have to make all your model objects manually. In CoreData, your inverse relationships get managed automatically for you... if you add an object to a to-many relationship in another object, you can traverse the graph in both directions. Without CoreData, is there any clean way to setup those inverse relationships automatically? For a more concrete example, let's take the typical Department and Employees example. To use rails terminology, a Department object has-many Employees, and an Employee belongs-to a Department. So our Department model has an NSMutableSet (or CPMutableSet ) "employees" that contains a set of Employees, and our Employee model has a variable "department" that points back to the Department model that owns it. Is there an easy way to make it so that, when I add a new Employee model into the set, the inverse relationship (employee.department) automatically gets set? Or the reverse: If I set the department model of an employee, then it automatically gets added to that department's employee set? Right know I'm making an object, "ValidatedModel" that all my models subclass, which adds a few methods that setup the inverse relationships, using KVO. But I'm afraid that I'm doing a lot of pointless work, and that there's already an easier way to do this. Can someone put my concerns to rest?

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  • Problems finding classes in namespace and testing extend expected parent

    - by Matt
    So I am in the process of building a site in ASP.Net MVC, and in the process I am adding certain things to my Site.Master I want to make sure that all of my model classes extend a certain base class that contains all of the pieces the Site.Master needs to be operable. I want to test to make sure this assumption isn't broken (I believe this will save me time when I forget about it and can't figure out why a new combination isn't working.) I wrote a test that I thought would help with this, but I am running into two problems. First it isn't finding the one example model class I have so far in the LINQ call all of a sudden, I am admittedly still a bit new to LINQ. Second, I had it finding the class earlier, but I couldn't get it to verify that the class inherits from the base class. Here is the example test. [Test] public void AllModelClassesExtendAbstractViewModel() { var abstractViewModelType = typeof (AbstractViewModel); Assembly baseAssembly = Assembly.GetAssembly(abstractViewModelType); var modelTypes = baseAssembly.GetTypes() .Where(assemblyType => (assemblyType.Namespace.EndsWith("Models") && assemblyType.Name != "AbstractViewModel")) .Select(assemblyType => assemblyType); foreach (var modelType in modelTypes) { Assert.That(modelType.IsSubclassOf(abstractViewModelType), Is.True , modelType.Name + " does not extend AbstractViewModel"); } }

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  • Best way to make a WYSIWYG in Flex?

    - by hngry4powr
    Hello, I have a client that wants a WYSIWYG form that behaves like MS word. It will have some section labels in it, with users expected to enter notes for each section, and it needs a place holder for a chart. The trick is that the user needs to know where page breaks are going to fall when printed. The customer agrees to fixed size paper with fixed sized margins. How should I approach this challenge? Thank you very much for your suggestions. Here is an example: Section 1: Explain Idea Here { As user types in this section, the space between this section and the next section expands, but I as the user can't delete the lines that say Section 1 or 2, or the place holder for the chart. However if I type a lot of text, I need to display where the page breaks are with a dashed line or something, so the user can make sure the content enters appears on the desired page. If I type a lot here for example, section 2 will get pushed onto the next page} Section 2: State why this is a Good Idea [ PLACE HOLDER FOR CHART . . . ] Section 3: Additional Remarks:

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  • PHP XML Parsing

    - by ashchawla
    Hi I am making get request in PHP but the parser is having issues. I am looking for a way to retreive the value of URL in the following example. The response xml looks like this. <?xml version="1.0" encoding="iso-8859-1" standalone="no"?> <testtemplate JobName="test1"> <Sources> <Source xmlns="http://www.microsoft.com/test/schema/api"> <System> <SystemIdentifier>HTTPS</SystemIdentifier> <URL>http://example.com</URL> </System> </Source> </Sources> <testtemplate> and my PHP code looks like this: $xml = DOMDocument::LoadXML($response); $mypath = new DOMXPath($xml); $mypath->registerNamespace("a", "http://www.microsoft.com/test/schema/api"); $url = $mypath->evaluate("/testtemplate/Sources/Source/System/URL"); $message = $url->item(0)->value; print($message); Any help would be appreciated. Thanks Ashish

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  • C# - Advantages/Disadvantages of different implementations for Comparing Objects

    - by Kevin Crowell
    This questions involves 2 different implementations of essentially the same code. First, using delegate to create a Comparison method that can be used as a parameter when sorting a collection of objects: class Foo { public static Comparison<Foo> BarComparison = delegate(Foo foo1, Foo foo2) { return foo1.Bar.CompareTo(foo2.Bar); }; } I use the above when I want to have a way of sorting a collection of Foo objects in a different way than my CompareTo function offers. For example: List<Foo> fooList = new List<Foo>(); fooList.Sort(BarComparison); Second, using IComparer: public class BarComparer : IComparer<Foo> { public int Compare(Foo foo1, Foo foo2) { return foo1.Bar.CompareTo(foo2.Bar); } } I use the above when I want to do a binary search for a Foo object in a collection of Foo objects. For example: BarComparer comparer = new BarComparer(); List<Foo> fooList = new List<Foo>(); Foo foo = new Foo(); int index = fooList.BinarySearch(foo, comparer); My questions are: What are the advantages and disadvantages of each of these implementations? What are some more ways to take advantage of each of these implementations? Is there a way to combine these implementations in such a way that I do not need to duplicate the code? Can I achieve both a binary search and an alternative collection sort using only 1 of these methods?

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  • How to map combinations of things to a relational database?

    - by Space_C0wb0y
    I have a table whose records represent certain objects. For the sake of simplicity I am going to assume that the table only has one row, and that is the unique ObjectId. Now I need a way to store combinations of objects from that table. The combinations have to be unique, but can be of arbitrary length. For example, if I have the ObjectIds 1,2,3,4 I want to store the following combinations: {1,2}, {1,3,4}, {2,4}, {1,2,3,4} The ordering is not necessary. My current implementation is to have a table Combinations that maps ObjectIds to CombinationIds. So every combination receives a unique Id: ObjectId | CombinationId ------------------------ 1 | 1 2 | 1 1 | 2 3 | 2 4 | 2 This is the mapping for the first two combinations of the example above. The problem is, that the query for finding the CombinationId of a specific Combination seems to be very complex. The two main usage scenarios for this table will be to iterate over all combinations, and the retrieve a specific combination. The table will be created once and never be updated. I am using SQLite through JDBC. Is there any simpler way or a best practice to implement such a mapping?

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  • How do I find all paths through a set of given nodes in a DAG?

    - by Hanno Fietz
    I have a list of items (blue nodes below) which are categorized by the users of my application. The categories themselves can be grouped and categorized themselves. The resulting structure can be represented as a Directed Acyclic Graph (DAG) where the items are sinks at the bottom of the graph's topology and the top categories are sources. Note that while some of the categories might be well defined, a lot is going to be user defined and might be very messy. Example: On that structure, I want to perform the following operations: find all items (sinks) below a particular node (all items in Europe) find all paths (if any) that pass through all of a set of n nodes (all items sent via SMTP from example.com) find all nodes that lie below all of a set of nodes (intersection: goyish brown foods) The first seems quite straightforward: start at the node, follow all possible paths to the bottom and collect the items there. However, is there a faster approach? Remembering the nodes I already passed through probably helps avoiding unnecessary repetition, but are there more optimizations? How do I go about the second one? It seems that the first step would be to determine the height of each node in the set, as to determine at which one(s) to start and then find all paths below that which include the rest of the set. But is this the best (or even a good) approach? The graph traversal algorithms listed at Wikipedia all seem to be concerned with either finding a particular node or the shortest or otherwise most effective route between two nodes. I think both is not what I want, or did I just fail to see how this applies to my problem? Where else should I read?

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  • Problem using unicode in URLs with cgi.PATH_INFO in ColdFusion

    - by Loftx
    Hi there, My ColdFusion (MX7) site has search functionality which appends the search term to the URL e.g. http://www.example.com/search.cfm/searchterm. The problem I'm running into is this is a multilingual site, so the search term may be in another language e.g. ??????? leading to a search URL such as http://www.example.com/search.cfm/??????? The problem is when I come to retrieve the search term from the URL. I'm using cgi.PATH_INFO to retrieve the path of the search page and the search term and extracting the search term from this e.g. /search.cfm/searchterm however, when unicode characters are used in the search they are converted to question marks e.g. /search.cfm/??????. These appear actual question marks, rather than the browser not being able to format unicode characters, or them being mangled on output. I can't find any information about whether ColdFusion supports unicode in the URL, or how I can go about resolving this and getting hold of the complete URL in some way - does anyone have any ideas? Cheers, Tom

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  • Getting random record from database with group by

    - by Saif Bechan
    Hello i have a question on picking random entries from a database. I have 4 tables, products, bids and autobids, and users. Products ------- id 20,21,22,23,24(prime_key) price........... etc........... users ------- id(prim_key) name user1,user2,user3 etc bids ------- product_id user_id created autobids -------- user_id product_id Now a multiple users can have an autobid on an product. So for the next bidder I want to select a random user from the autobid table example of the query in language: for each product in the autobid table I want a random user, which is not the last bidder. On product 20 has user1,user2,user3 an autobidding. On product 21 has user1,user2,user3 an autobidding Then I want a resultset that looks for example like this 20 – user2 21 – user3 Just a random user. I tried miximg the GOUP BY (product_id) and making it RAND(), but I just can't get the right values from it. Now I am getting a random user, but all the values that go with it don't match. Can someone please help me construct this query, I am using php and mysql

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  • CSS style refresh in IE after dynamic removal of style link

    - by rybz
    Hi! I've got a problem with the dynamic style manipulation in IE7 (IE8 is fine). Using javascript I need to add and remove the < link / node with the definition of css file. Adding and removing the node as a child of < head / works fine under Firefox. Unfortunately, after removing it in the IE, although The tag is removed properly, the page style does not refresh. In the example below a simple css (makes background green) is appended and removed. After the removal in FF the background turns default, but in IE stays green. index.html <html> <head> </head> <script language="javascript" type="text/javascript"> var node; function append(){ var headID = document.getElementsByTagName("head")[0]; node = document.createElement('link'); node.type = 'text/css'; node.rel = 'stylesheet'; node.href = "s.css"; node.media = 'screen'; headID.appendChild(node); } function remove(){ var headID = document.getElementsByTagName("head")[0]; headID.removeChild(node); } </script> <body> <div onClick="append();"> add </div> <div onClick="remove();"> remove </div> </body> </html> And the style sheet: s.css body { background-color:#00CC33 } Here is the live example: http://rlab.pl/dynamic-style/ Is there a way to get it working?

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  • How does one implement storage/retrieval of smart-search/mailbox features?

    - by humble_coder
    Hi All, I have a question regarding implementation of smart-search features. For example, consider something like "smart mailboxes" in various email applications. Let's assume you have your data (emails) stored in a database and, depending on the field for which the query will be created, you present different options to the end user. At the moment let's assume the Subject, Verb, Object approach… For instance, say you have the following: SUBJECTs: message, to_address, from_address, subject, date_received VERBs: contains, does_not_contain, is_equal_to, greater_than, less_than OBJECTs: ??????? Now, in case it isn't clear, I want a table structure (although I'm not opposed to an external XMLesque file of some sort) to store (and later retrieve/present) my criteria for smart searches/mailboxes for later use. As an example, using SVO I could easily store then reconstruct a query for "date between two dates" -- simply use "date greater than" AND "date less than". However, what if, in the same smart search, I wanted a "between" OR'ed with another criterion? You can see that it might get out of hand -- not necessarily in the query creation (as that is rather simplistic), but in the option presentation and storage mechanism. Perhaps I need to think more on a more granular level. Perhaps I need to simply allow the user to select AND or OR for each entry independently instead of making it an ALL OR NOTHING type smart search (i.e. instead of MATCH ALL or MATCH ANY, I need to simply allow them to select -- I just don't want it to turn into a Hydra). Any input would be most appreciated. My apologies if the question is a bit incoherent. It is late, and I my brain is toast. Best.

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  • Getting all selected checkboxes values using ajax and jsp/servlets?

    - by A.S al-shammari
    Hi.. I'm developing a jsp/serlvet application. I have a page with a list of inputs as checkboxes . I want to send values of selected buttons to a servlet using ajax/jquery. In the servlet , I want to extract these values and use them . for example: The user checks some checkboxes , for example, list of messages. He/She presses Delete Link to delete selected messages. I searched and found something like this : $("#inboxDeleteSelected").click(function(){ var data = { 'checkBoxList[]' : []}; var list=$(":input:checkbox:checked"); // getting all selected checkboxes. $(list.each(function() { data['checkBoxList[]'].push($(this).val()); })); $.post("servlet?do=deleteSelected",data,function(d){ // do something here }); }); My questions: How can I send selected checkboxes values to a servlet ? How can I extract these values in the servlet ? Note: I don't use submit button to submit the selected checkboxes,Indeed I use link/anchor to send those values .

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  • How would I code a complex formula parser manually?

    - by StormianRootSolver
    Hm, this is language - agnostic, I would prefer doing it in C# or F#, but I'm more interested this time in the question "how would that work anyway". What I want to accomplish ist: a) I want to LEARN it - it's about my ego this time, it's for a fun project where I want to show myself that I'm a really good at this stuff b) I know a tiny little bit about EBNF (although I don't know yet, how operator precedence works in EBNF - Irony.NET does it right, I checked the examples, but this is a bit ominous to me) c) My parser should be able to take this: 5 * (3 + (2 - 9 * (5 / 7)) + 9) for example and give me the right results d) To be quite frankly, this seems to be the biggest problem in writing a compiler or even an interpreter for me. I would have no problem generating even 64 bit assembler code (I CAN write assembler manually), but the formula parser... e) Another thought: even simple computers (like my old Sharp 1246S with only about 2kB of RAM) can do that... it can't be THAT hard, right? And even very, very old programming languages have formula evaluation... BASIC is from 1964 and they already could calculate the kind of formula I presented as an example f) A few ideas, a few inspirations would be really enough - I just have no clue how to do operator precedence and the parentheses - I DO, however, know that it involves an AST and that many people use a stack So, what do you think?

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  • NHibernate / Fluent - Mapping multiple objects to single lookup table

    - by Al
    Hi all I am struggling a little in getting my mapping right. What I have is a single self joined table of look up values of certain types. Each lookup can have a parent, which can be of a different type. For simplicities sake lets take the Country and State example. So the lookup table would look like this: Lookups Id Key Value LookupType ParentId - self joining to Id base class public class Lookup : BaseEntity { public Lookup() {} public Lookup(string key, string value) { Key = key; Value = value; } public virtual Lookup Parent { get; set; } [DomainSignature] [NotNullNotEmpty] public virtual LookupType LookupType { get; set; } [NotNullNotEmpty] public virtual string Key { get; set; } [NotNullNotEmpty] public virtual string Value { get; set; } } The lookup map public class LookupMap : IAutoMappingOverride<DBLookup> { public void Override(AutoMapping<Lookup> map) { map.Table("Lookups"); map.References(x => x.Parent, "ParentId").ForeignKey("Id"); map.DiscriminateSubClassesOnColumn<string>("LookupType").CustomType(typeof(LookupType)); } } BASE SubClass map for subclasses public class BaseLookupMap : SubclassMap where T : DBLookup { protected BaseLookupMap() { } protected BaseLookupMap(LookupType lookupType) { DiscriminatorValue(lookupType); Table("Lookups"); } } Example subclass map public class StateMap : BaseLookupMap<State> { protected StateMap() : base(LookupType.State) { } } Now I've almost got my mappings set, however the mapping is still expecting a table-per-class setup, so is expecting a 'State' table to exist with a reference to the states Id in the Lookup table. I hope this makes sense. This doesn't seem like an uncommon approach when wanting to keep lookup-type values configurable. Thanks in advance. Al

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  • If the dependency is a unique snapshot version and install is called, what does maven select?

    - by chrsk
    Imagine two projects. The first is the framework-core project which is in version 1.1.0 and has several snapshot builds. The other is the example-business project which has the following dependency to framework-core on the build-iteration number 9. <dependency> <groupId>org.example</groupId> <artifactId>framework-core</artifactId> <version>1.1.0-20100518.134928-9</version> </dependency> What happens if mvn install is called on the framework-core? I found out that the artifact is copied to the folder and is named to *.1.1.0-SNAPSHOT.jar (as expected). This lead me to the assumption that this version is only used if even this 1.1.0-SNAPSHOT version is defined as dependency and not the precise build. To test something local without deploying it to the maven repository: call mvn install, change the dependency to 1.1.0-SNAPSHOT -- and the artifact just installed is used? Or is it possible to overwrite the specific build (with using the install lifecycle phase)?

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  • Parsing multiple files at a time in Perl

    - by sfactor
    I have a large data set (around 90GB) to work with. There are data files (tab delimited) for each hour of each day and I need to perform operations in the entire data set. For example, get the share of OSes which are given in one of the columns. I tried merging all the files into one huge file and performing the simple count operation but it was simply too huge for the server memory. So, I guess I need to perform the operation each file at a time and then add up in the end. I am new to perl and am especially naive about the performance issues. How do I do such operations in a case like this. As an example two columns of the file are. ID OS 1 Windows 2 Linux 3 Windows 4 Windows Lets do something simple, counting the share of the OSes in the data set. So, each .txt file has millions of these lines and there are many such files. What would be the most efficient way to operate on the entire files.

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  • Visitor Pattern can be replaced with Callback functions?

    - by getit
    Is there any significant benefit to using either technique? In case there are variations, the Visitor Pattern I mean is this: http://en.wikipedia.org/wiki/Visitor_pattern And below is an example of using a delegate to achieve the same effect (at least I think it is the same) Say there is a collection of nested elements: Schools contain Departments which contain Students Instead of using the Visitor pattern to perform something on each collection item, why not use a simple callback (Action delegate in C#) Say something like this class Department { List Students; } class School { List Departments; VisitStudents(Action<Student> actionDelegate) { foreach(var dep in this.Departments) { foreach(var stu in dep.Students) { actionDelegate(stu); } } } } School A = new School(); ...//populate collections A.Visit((student)=> { ...Do Something with student... }); *EDIT Example with delegate accepting multiple params Say I wanted to pass both the student and department, I could modify the Action definition like so: Action class School { List Departments; VisitStudents(Action<Student, Department> actionDelegate, Action<Department> d2) { foreach(var dep in this.Departments) { d2(dep); //This performs a different process. //Using Visitor pattern would avoid having to keep adding new delegates. //This looks like the main benefit so far foreach(var stu in dep.Students) { actionDelegate(stu, dep); } } } }

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