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  • How to handle authenticated user access to resources in document oriented system?

    - by Jeremy Raymond
    I'm developing a document oriented application and need to manage user access to the documents. I have a module that handles user authentication, and another module that handles document CRUD operations on the data store. Once a user is authenticated I need to enforce what operations the user can and cannot perform to documents based upon the user's permissions. The best option I could think of to integrate these two pieces together would be to create another module that duplicates the data API but that also takes the authenticated user as a parameter. The module would delegate the authorization check to the auth module and delegate the document operation to the data access module. Something like: -module(auth_data_access). % User is authenticated (logged into the system) % save_doc validates if user is allowed to save the given document and if so % saves it returning ok, else returns {error, permission_denied} save_doc(Doc, User) -> case auth:save_allowed(Doc, User) of ok -> data_access:save_doc(Doc); denied -> {error, permission_denied} end end. Is there a better way I can handle this?

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  • How much effort do you have to put in to get gains from using SSE?

    - by John
    Case One Say you have a little class: class Point3D { private: float x,y,z; public: operator+=() ...etc }; Point3D &Point3D::operator+=(Point3D &other) { this->x += other.x; this->y += other.y; this->z += other.z; } A naive use of SSE would simply replace these function bodies with using a few intrinsics. But would we expect this to make much difference? MMX used to involve costly state cahnges IIRC, does SSE or are they just like other instructions? And even if there's no direct "use SSE" overhead, would moving the values into SSE registers and back out again really make it any faster? Case Two Instead, you're working with a less OO-based code base. Rather than an array/vector of Point3D objects, you simply have a big array of floats: float coordinateData[NUM_POINTS*3]; void add(int i,int j) //yes it's unsafe, no overlap check... example only { for (int x=0;x<3;++x) { coordinateData[i*3+x] += coordinateData[j*3+x]; } } What about use of SSE here? Any better? In conclusion Is trying to optimise single vector operations using SSE actually worthwhile, or is it really only valuable when doing bulk operations?

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  • When to call Dispose in Entity Framework?

    - by Abdel Olakara
    Hi All, In my application I am making use of Spring.Net for IoC. The service objects are called from the ASP.Net files to perform CRUD operations using these service object. For example, I have CustomerService to do all CRUD operations on Customer table. I use entity framework and the entities are injected .. my question is where do I call the dispose method? As far as I understood from the API documentations, unless I call Dispose() there is no guaranty it will be garbage collected! So where and how do I do it? Example Service Class: public class CustomerService { public ecommEntities entities = {get; set;} public bool AddCustomer(Customer customer) { try { entities.AddToCustomer(customer); entities.SaveChanges(); return true; } catch (Exception e) { log.Error("Error occured during creation of new customer: " + e.Message + e.StackTrace); return false; } } public bool UpdateCustomer(Customer customer) { entities.SaveChanges(); return true; } public bool DeleteCustomer(Customer customer) . . . And I just create an object of CustomerService at the ASP partial class and call the necessary methods. Thanks in advance for the best practice and ideas.. Regards, Abdel Raoof

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  • Is there really such a thing as a char or short in modern programming?

    - by Dean P
    Howdy all, I've been learning to program for a Mac over the past few months (I have experience in other languages). Obviously that has meant learning the Objective C language and thus the plainer C it is predicated on. So I have stumbles on this quote, which refers to the C/C++ language in general, not just the Mac platform. With C and C++ prefer use of int over char and short. The main reason behind this is that C and C++ perform arithmetic operations and parameter passing at integer level, If you have an integer value that can fit in a byte, you should still consider using an int to hold the number. If you use a char, the compiler will first convert the values into integer, perform the operations and then convert back the result to char. So my question, is this the case in the Mac Desktop and IPhone OS environments? I understand when talking about theses environments we're actually talking about 3-4 different architectures (PPC, i386, Arm and the A4 Arm variant) so there may not be a single answer. Nevertheless does the general principle hold that in modern 32 bit / 64 bit systems using 1-2 byte variables that don't align with the machine's natural 4 byte words doesn't provide much of the efficiency we may expect. For instance, a plain old C-Array of 100,000 chars is smaller than the same 100,000 ints by a factor of four, but if during an enumeration, reading out each index involves a cast/boxing/unboxing of sorts, will we see overall lower 'performance' despite the saved memory overhead?

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  • How to make a increasing numbers after filenames in C?

    - by zaplec
    Hi, I have a little problem. I need to do some little operations on quite many files in one little program. So far I have decided to operate them in a single loop where I just change the number after the name. The files are all named TFxx.txt where xx is increasing number from 1 to 80. So how can I open them all in a single loop one after one? I have tried this: for(i=0; i<=80; i++) { char name[8] = "TF"+i+".txt"; FILE = open(name, r); /* Do something */ } As you can see the second line would be working in python but not in C. I have tried to do similiar running numbering with C to this program, but I haven't found out yet how to do that. The format doesn't need to be as it is on the second line, but I'd like to have some advice of how can I solve this problem. All I need to do is just be able to open many files and do same operations to them.

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  • What are the fastest-performing options for a read-only, unordered collection of unique strings?

    - by Dan Tao
    Disclaimer: I realize the totally obvious answer to this question is HashSet<string>. It is absurdly fast, it is unordered, and its values are unique. But I'm just wondering, because HashSet<T> is a mutable class, so it has Add, Remove, etc.; and so I am not sure if the underlying data structure that makes these operations possible makes certain performance sacrifices when it comes to read operations -- in particular, I'm concerned with Contains. Basically, I'm wondering what are the absolute fastest-performing data structures in existence that can supply a Contains method for objects of type string. Within or outside of the .NET framework itself. I'm interested in all kinds of answers, regardless of their limitations. For example I can imagine that some structure might be restricted to strings of a certain length, or may be optimized depending on the problem domain (e.g., range of possible input values), etc. If it exists, I want to hear about it. One last thing: I'm not restricting this to read-only data structures. Obviously any read-write data structure could be embedded inside a read-only wrapper. The only reason I even mentioned the word "read-only" is that I don't have any requirement for a data structure to allow adding, removing, etc. If it has those functions, though, I won't complain.

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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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  • ASP.NET Response Filter to Reformat the rendered output of ASPX pages?

    - by PropellerHead
    I've created a simple HttpModule and response stream to reformat the rendered output of web pages (see code snippets below). In the HttpModule I set the Response.Filter to my PageStream: m_Application.Context.Response.Filter = new PageStream(m_Application.Context); In the PageStream I overwrite the Write method in order to do my reformatting of the rendered output: public override void Write(byte[] buffer, int offset, int count) { string html = System.Text.Encoding.UTF8.GetString(buffer); //Do some string resplace operations here... byte[] input = System.Text.Encoding.UTF8.GetBytes(html); m_DefaultStream.Write(input, 0, input.Length); } And this work fine when using it on simple HTML pages (.html), but when I use this method on ASPX pages (.aspx), the Write method is called several times, splitting up the reformatting into different steps, and potentially destroying the string replacement operations. How do I solve this? Is there a way to let the ASPX page NOT call Write several times, e.g. by changing its buffer size, or have I chosen the wrong approach entirely, by using this Response.Filter method to manipulate the rendered output?

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  • Endianness and C API's: Specifically OpenSSL.

    - by Hassan Syed
    I have an algorithm that uses the following OpenSSL calls: HMAC_update() / HMAC_final() // ripe160 EVP_CipherUpdate() / EVP_CipherFinal() // cbc_blowfish These algorithm take a unsigned char * into the "plain text". My input data is comes from a C++ std::string::c_str() which originate from a protocol buffer object as a encoded UTF-8 string. UTF-8 strings are meant to be endian neutrial. However I'm a bit paranoid about how OpenSSL may perform operations on the data. My understanding is that encryption algorithms work on 8-bit blocks of data, and if a unsigned char * is used for pointer arithmetic when the operations are performed the algorithms should be endian neutral and I do not need to worry about anything. My uncertainty is compounded by the fact that I am working on a little-endian machine and have never done any real cross-architecture programming. My beliefs/reasoning are/is based on the following two properties std::string (not wstring) internally uses a 8-bit ptr and a the resulting c_str() ptr will itterate the same way regardless of the CPU architecture. Encryption algorithms are either by design, or by implementation, endian neutral. I know the best way to get a definitive answer is to use QEMU and do some cross-platform unit tests (which I plan to do). My question is a request for comments on my reasoning, and perhaps will assist other programmers when faced with similar problems.

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  • Nullability (Regular Expressions)

    - by danportin
    In Brzozowski's "Derivatives of Regular Expressions" and elsewhere, the function d(R) returning ? if a R is nullable, and Ø otherwise, includes clauses such as the following: d(R1 + R2) = d(R1) + d(R2) d(R1 · R2) = d(R1) ? d(R2) Clearly, if both R1 and R2 are nullable then (R1 · R2) is nullable, and if either R1 or R2 is nullable then (R1 + R2) is nullable. It is unclear to me what the above clauses are supposed to mean, however. My first thought, mapping (+), (·), or the Boolean operations to regular sets is nonsensical, since in the base case, d(a) = Ø (for all a ? S) d(?) = ? d(Ø) = Ø and ? is not a set (nor is the return type of d, which is a regular expression). Furthermore, this mapping isn't indicated, and there is a separate notation for it. I understand nullability, but I'm lost on the definition of the sum, product, and Boolean operations in the definition of d: how are ? or Ø returned from d(R1) ? d(R2), for instance, in the definition off d(R1 · R2)?

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  • Conditional insert as a single database transaction in HSQLDB 1.8?

    - by Kevin Pauli
    I'm using a particular database table like a "Set" data structure, i.e., you can attempt to insert the same row several times, but it will only contain one instance. The primary key is a natural key. For example, I want the following series of operations to work fine, and result in only one row for Oklahoma: insert into states_visited (state_name) values ('Oklahoma'); insert into states_visited (state_name) values ('Texas'); insert into states_visited (state_name) values ('Oklahoma'); I am of course getting an error due to the duplicate primary key on subsequent inserts of the same value. Is there a way to make the insert conditional, so that these errors are not thrown? I.e. only do the the insert if the natural key does not already exist? I know I could do a where clause and a subquery to test for the row's existence first, but it seems that would be expensive. That's 2 physical operations for one logical "conditional insert" operation. Anything like this in SQL? FYI I am using HSQLDB 1.8

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  • How to display a busy message over a wpf screen

    - by dave
    Hey, I have a WPF application based on Prism4. When performing slow operations, I want to show a busy screen. I will have a large number of screens, so I'm trying to build a single solution into the framework rather than adding the busy indicator to each screen. These long running operations run in a background thread. This allows the UI to be updated (good) but does not stop the user from using the UI (bad). What I'd like to do is overlay a control with a spinning dial sort of thing and have that control cover the entire screen (the old HTML trick with DIVs). When the app is busy, the control would display thus block any further interaction as well as showing the spinny thing. To set this up, I thought I could just have my app screen in a canvas along with the spinny thing (with a greater ZIndex) then just make the spinny thing visible as required. This, however, is getting hard. Canvases do not seem well set up for this and I think I might be barking up the wrong tree. I would appreciate any help. Thanks.

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  • how to merge ecommerce transaction data between two databases

    - by yamspog
    We currently run an ecommerce solution for a leisure and travel company. Everytime we have a release, we must bring the ecommerce site down as we update database schema and the data access code. We are using a custom built ORM where each data entity is responsible for their own CRUD operations. This is accomplished by dynamically generating the SQL based on attributes in the data entity. For example, the data entity for an address would be... [tableName="address"] public class address : dataEntity { [column="address1"] public string address1; [column="city"] public string city; } So, if we add a new column to the database, we must update the schema of the database and also update the data entity. As you can expect, the business people are not too happy about this outage as it puts a crimp in their cash-flow. The operations people are not happy as they have to deal with a high-pressure time when database and applications are upgraded. The programmers are upset as they are constantly getting in trouble for the legacy system that they inherited. Do any of you smart people out there have some suggestions?

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  • Creating collaborative whiteboard drawing application

    - by Steven Sproat
    I have my own drawing program in place, with a variety of "drawing tools" such as Pen, Eraser, Rectangle, Circle, Select, Text etc. It's made with Python and wxPython. Each tool mentioned above is a class, which all have polymorphic methods, such as left_down(), mouse_motion(), hit_test() etc. The program manages a list of all drawn shapes -- when a user has drawn a shape, it's added to the list. This is used to manage undo/redo operations too. So, I have a decent codebase that I can hook collaborative drawing into. Each shape could be changed to know its owner -- the user who drew it, and to only allow delete/move/rescale operations to be performed on shapes owned by one person. I'm just wondering the best way to develop this. One person in the "session" will have to act as the server, I have no money to offer free central servers. Somehow users will need a way to connect to servers, meaning some kind of "discover servers" browser...or something. How do I broadcast changes made to the application? Drawing in realtime and broadcasting a message on each mouse motion event would be costly in terms of performance and things get worse the more users there are at a given time. Any ideas are welcome, I'm not too sure where to begin with developing this (or even how to test it)

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  • java: libraries for immutable functional-style data structures

    - by Jason S
    This is very similar to another question (Functional Data Structures in Java) but the answers there are not particularly useful. I need to use immutable versions of the standard Java collections (e.g. HashMap / TreeMap / ArrayList / LinkedList / HashSet / TreeSet). By "immutable" I mean immutable in the functional sense (e.g. purely functional data structures), where updating operations on the data structure do not change the original data, but instead return a new instance of the same kind of data structure. Also typically new and old instances of the data structure will share immutable data to be efficient in time and space. From what I can tell my options include: Functional Java Scala Clojure but I'm not sure whether any of these are particularly appealing to me. I have a few requirements/desirements: the collections in question should be usable directly in Java (with the appropriate libraries in the classpath). FJ would work for me; I'm not sure if I can use Scala's or Clojure's data structures in Java w/o having to use the compilers/interpreters from those languages and w/o having to write Scala or Clojure code. Core operations on lists/maps/sets should be possible w/o having to create function objects with confusing syntaxes (FJ looks slightly iffy) They should be efficient in time and space. I'm looking for a library which ideally has done some performance testing. FJ's TreeMap is based on a red-black tree, not sure how that rates. Documentation / tutorials should be good enough so someone can get started quickly using the data structures. FJ fails on that front. Any suggestions?

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  • Clarification of atomic memory access for different OSs

    - by murrekatt
    I'm currently porting a Windows C++ library to MacOS as a hobby project as a learning experience. I stumbled across some code using the Win Interlocked* functions and thus I've been trying to read up on the subject in general. Reading related questions here in SO, I understand there are different ways to do these operations depending on the OS. Interlocked* in Windows, OSAtomic* in MacOS and I also found that compilers have builtin (intrinsic) operations for this. After reading gcc builtin atomic memory access, I'm left wondering what is the difference between intrinsic and the OSAtomic* or Interlocked* ones? I mean, can I not choose between OSAtomic* or gcc builtin if I'm on MacOS when I use gcc? The same if I'd be on Windows using gcc. I also read that on Windows Interlocked* come as both inline and intrinsic versions. What to consider when choosing between intrinsic or inline? In general, are there multiple options on OSs what to use? Or is this again "it depends"? If so, what does it depend on? Thanks!

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  • preload image with jquery

    - by robertdd
    ok, I spent 2 days trying to preloaded images but no succes! i have this function: jQuery.getlastimage = function(id) { $.getjs(); $.post('operations.php', {'operation':'getli', 'id':id,}, function(lastimg){ $("#upimages" + id).html('<a href="uploads/'+ lastimg +'?'+ (new Date()).getTime() +'"><img class="thumbs" id="' + id + '" alt="' + lastimg + '" src="uploads/' + lastimg +'?'+ (new Date()).getTime() + '" /></a>'); }); }; while the image loading i want to appear a gif or a text "Loading...". the function will get something like this: <div class="upimage"> <ul class="thumbs" id="upimagesQueue"> **<li id="#upimagesRIFDIB"> <a href="uploads/0001.jpg?1271800088379"> <img src="uploads/0001.jpg?1271800088379" alt="0001.jpg" id="RIFDIB" class="thumbs"> </a> </li>** <li> .... </li> </ul> </div> i tryed like this: ... $.post('operations.php', {'operation':'getli', 'id':id,}, function(lastimg){ $("#upimages" + id) .html('<a href="uploads/'+ lastimg +'?'+ (new Date()).getTime() +'"><img class="thumbs" id="' + id + '" alt="' + lastimg + '" src="uploads/' + lastimg +'?'+ (new Date()).getTime() + '" /></a>') .hide() .load(function() { $(this).show(); }); ... but all the <li> will hide and after is loading the image appear, i want the <li> to apear with a gif or a text in it and after the image is loaded the link and the image to apear! How to do this? Anyone have an idea? Thanks!

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  • C++ Matrix class hierachy

    - by bpw1621
    Should a matrix software library have a root class (e.g., MatrixBase) from which more specialized (or more constrained) matrix classes (e.g., SparseMatrix, UpperTriangluarMatrix, etc.) derive? If so, should the derived classes be derived publicly/protectively/privately? If not, should they be composed with a implementation class encapsulating common functionality and be otherwise unrelated? Something else? I was having a conversation about this with a software developer colleague (I am not per se) who mentioned that it is a common programming design mistake to derive a more restricted class from a more general one (e.g., he used the example of how it was not a good idea to derive a Circle class from an Ellipse class as similar to the matrix design issue) even when it is true that a SparseMatrix "IS A" MatrixBase. The interface presented by both the base and derived classes should be the same for basic operations; for specialized operations, a derived class would have additional functionality that might not be possible to implement for an arbitrary MatrixBase object. For example, we can compute the cholesky decomposition only for a PositiveDefiniteMatrix class object; however, multiplication by a scalar should work the same way for both the base and derived classes. Also, even if the underlying data storage implementation differs the operator()(int,int) should work as expected for any type of matrix class. I have started looking at a few open-source matrix libraries and it appears like this is kind of a mixed bag (or maybe I'm looking at a mixed bag of libraries). I am planning on helping out with a refactoring of a math library where this has been a point of contention and I'd like to have opinions (that is unless there really is an objective right answer to this question) as to what design philosophy would be best and what are the pros and cons to any reasonable approach.

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  • Which templating languages output HTML *as a tree of nodes*?

    - by alamar
    HTML is a tree of nodes, before all. It's not just a text. However, most templating engines handle their input and output as it was just a text; they don't care what happens around their tags, their {$foo}'s and <% bar() %>'s; also they don't care about what are they outputting. Sometimes they happen to produce a correct html, but that's just a coincidence; they didn't aim for that, all they wanted is to replace some funny marks in the text stream with their evaluation. There are a few templating engines which do treat their output as a set of nodes; XSLT and Haml come to mind. For some tasks, this has advantages: for example, you can automatically reformat (like, delete all empty text nodes; auto-indent; word-wrap). The result is guaranteed to be a correct xml/sgml unless you use a strict subset of operations that can break that. Also, such templating engine would automatically quote strings, differently in text nodes and in attributes, because it strictly knows whether you're writing an attribute or a text node. Moreover, it can conditionally remove a node from output because it knows where it does begin and end, which is useful, and do other non-trivial node operations. You might not like XSLT for its verbosiness or functionalness, but it's damn helps that your template is xmllint-able XML, and your output is a good sgml/xml. So the question is: Which template engines do you know that treat their output as a set of correct nodes, not just an unstructured text? I know XSLT, Haml and some obscure python-based one. Moar!

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  • Doctrine 2 entity cannot be saved with its many-to-many related entities

    - by user1333185
    I'm writing a project in ZF and have many-to-many related accounts and videos entities and I provide the account with the videos collection. When I try to save the account I receive the following error: A new entity was found through the relationship 'Entities\Account#playlistVideos' that was not configured to cascade persist operations for entity: Entities\Video@000000004d5f02ef00000000196757dc. Explicitly persist the new entity or configure cascading persist operations on the relationship. If you cannot find out which entity causes the problem implement 'Entities\Video#__toString()' to get a clue. I found a suggested solution with cascade={"persist"} which should allow videos to be saved together with the account by only specifying $this-em-persist($account) but then I get the error: Fatal error: method_exists(): The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "Proxies\EntitiesAccountProxy" of the object you are trying to operate on was loaded before unserialize() gets called or provide a __autoload() function to load the class definition in... The same happens when I try to manually persist videos and account. Thank you for the help in advance.

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  • how to minimize application downtime when updating database and application ORM

    - by yamspog
    We currently run an ecommerce solution for a leisure and travel company. Everytime we have a release, we must bring the ecommerce site down as we update database schema and the data access code. We are using a custom built ORM where each data entity is responsible for their own CRUD operations. This is accomplished by dynamically generating the SQL based on attributes in the data entity. For example, the data entity for an address would be... [tableName="address"] public class address : dataEntity { [column="address1"] public string address1; [column="city"] public string city; } So, if we add a new column to the database, we must update the schema of the database and also update the data entity. As you can expect, the business people are not too happy about this outage as it puts a crimp in their cash-flow. The operations people are not happy as they have to deal with a high-pressure time when database and applications are upgraded. The programmers are upset as they are constantly getting in trouble for the legacy system that they inherited. Do any of you smart people out there have some suggestions?

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  • NHibernate - Retrieving Lots of Data Becomes Exponentially Slow

    - by nfplee
    Hi, I have an issue when I retrieve lots of data in NHibernate (such as when producing a report) the page becomes exponentially slower the more data it has to retrieve. I found the following article: http://nhforge.org/blogs/nhibernate/archive/2008/10/30/bulk-data-operations-with-nhibernate-s-stateless-sessions.aspx It explains how doing bulk data operations in NHibernate is slow since the first level cache grows too large and how you should use the IStatelessSession instead. The trouble I have is that I don't wish to tie my application to NHibernate so I've added a wrapper around ISession. I then use Linq as my query mechanism but IStatelessSession does not support Linq (it may do in NHibernate 3 but the Linq provider is not stable as it stands at the moment). I then read that you could do a clear after so many iterations to clear out the first level cache. The problem now is that you can't use lazy loading. The linq provider doesn't allow you to override the mapping defined (or eagerly fetch the additional data) so whenever I grab data which is lazy loaded after I have cleared the session an exception is thrown. I'm completely lost on what do now. I like the ease of producing reports with linq but the limitations of the inbuilt linq provider in NHibernate seem to be holding me back. I'd really appreciate it if someone could show me an alternative approach. Thanks

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  • Glassfish complaining about JSF component IDs

    - by Brian
    Hello All I am very new to JSF (v2.0) and I am attempting to learn it at places like netbeans.org and coreservlets.com. I am working on a very simple "add/subtract/multiply/divide" Java webapp and I have run into a problem. When I first started out, the application was enter two numbers and hit a '+' key and they would be automatically added together. Now that I have added more complexity I am having trouble getting the operation to the managed bean. This is what I had when it was just "add": <h:inputText styleClass="display" id="number01" size="4" maxlength="3" value="#{Calculator.number01}" /> <h:inputText styleClass="display" id="number02" size="4" maxlength="3" value="#{Calculator.number02}" /> <h:commandButton id="add" action="answer" value="+" /> For the "answer" page, I display the answer like this: <h:outputText value="#{Calculator.answer}" /> I had the proper getters and setters in the Calculator.java managed bean and the operation worked perfectly. Now I have added the other three operations and I am having trouble visualizing how to get the operation parameter to the bean so that I can switch around it. I tried this: <h:commandButton id="operation" action="answer" value="+" /> <h:commandButton id="operation" action="answer" value="-" /> <h:commandButton id="operation" action="answer" value="*" /> <h:commandButton id="operation" action="answer" value="/" /> However, Glassfish complained that I have already used "operation" once and I am trying to use it four times here. Any adivce/tips on how to get multiple operations to the managed bean so that it can preform the desired operation? Thank you for taking the time to read.

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  • perl - universal operator overload

    - by Todd Freed
    I have an idea for perl, and I'm trying to figure out the best way to implement it. The idea is to have new versions of every operator which consider the undefined value as the identity of that operation. For example: $a = undef + 5; # undef treated as 0, so $a = 5 $a = undef . "foo"; # undef treated as '', so $a = foo $a = undef && 1; # undef treated as false, $a = true and so forth. ideally, this would be in the language as a pragma, or something. use operators::awesome; However, I would be satisfied if I could implement this special logic myself, and then invoke it where needed: use My::Operators; The problem is that if I say "use overload" inside My::Operators only affects objects blessed into My::Operators. So the question is: is there a way (with "use overoad" or otherwise) to do a "universal operator overload" - which would be called for all operations, not just operations on blessed scalars. If not - who thinks this would be a great idea !? It would save me a TON of this kind of code if($object && $object{value} && $object{value} == 15) replace with if($object{value} == 15) ## the special "is-equal-to" operator

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  • C Programming. How to deep copy a struct?

    - by user69514
    I have the following two structs where "child struct" has a "rusage struct" as an element. Then I create two structs of type "child" let's call them childA and childB How do I copy just the rusage struct from childA to childB? typedef struct{ int numb; char *name; pid_t pid; long userT; long systemT; struct rusage usage; }child; typedef struct{ struct timeval ru_utime; /* user time used */ struct timeval ru_stime; /* system time used */ long ru_maxrss; /* maximum resident set size */ long ru_ixrss; /* integral shared memory size */ long ru_idrss; /* integral unshared data size */ long ru_isrss; /* integral unshared stack size */ long ru_minflt; /* page reclaims */ long ru_majflt; /* page faults */ long ru_nswap; /* swaps */ long ru_inblock; /* block input operations */ long ru_oublock; /* block output operations */ long ru_msgsnd; /* messages sent */ long ru_msgrcv; /* messages received */ long ru_nsignals; /* signals received */ long ru_nvcsw; /* voluntary context switches */ long ru_nivcsw; /* involuntary context switches */ }rusage; I did the following, but I guess it copies the memory location, because if I changed the value of usage in childA, it also changes in childB. memcpy(&childA,&childB, sizeof(rusage)); I know that gives childB all the values from childA. I have already taken care of the others fields in childB, I just need to be able to copy the rusage struct called usage that resides in the "child" struct.

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