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• Deep copy objects from different namespaces

  - by Wasim

  Hi all, I have the following situation: I have class User with the follwing properies : public class User { string user name ; List <Contact> contacts ; List <BookMark> book marks; . . . } I have the same class in a different namespace , with some different properties . BWT , it's the same situation of it's classes (Contact) and (BookMark). I need to make a deep copy of the same properties from the two classes . Actually , I arrive to this situation by having an Entity Framework edmx file . I created the first database (SQL server 2008) from this model . And copied he same edmx file to another project and created the database with SQL CE db. Now I get the first data model objects by WCF service and need to persist them in the local database in my application . The objects are the same but there are some changs because of the modeling issue with a different databse. Do you have any workarround about this assue. Thanks in advance ...

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• Python: saving and loading objects and using pickle.

  - by Peterstone

  Hello, I´m trying to save and load objects using pickle module. First I declare my objects: >>> class Fruits:pass ... >>> banana = Fruits() >>> banana.color = 'yellow' >>> banana.value = 30 After that I open a file called 'Fruits.obj'(previously I created a new .txt file and I renamed 'Fruits.obj'): >>> import pickle >>> filehandler = open(b"Fruits.obj","wb") >>> pickle.dump(banana,filehandler) After do this I close my session and I began a new one and I put the next (trying to access to the object that it supposed to be saved): file = open("Fruits.obj",'r') object_file = pickle.load(file) But I have this message: Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Python31\lib\pickle.py", line 1365, in load encoding=encoding, errors=errors).load() ValueError: read() from the underlying stream did notreturn bytes I don´t know what to do because I don´t understand this message. Does anyone know How I can load my object 'banana'? Thank you! EDIT: As some of you have sugested I put: >>> import pickle >>> file = open("Fruits.obj",'rb') There were no problem, but the next I put was: >>> object_file = pickle.load(file) And I have error: Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Python31\lib\pickle.py", line 1365, in load encoding=encoding, errors=errors).load() EOFError

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• Data Annotations on ViewModels or Domain Objects

  - by Ahmad

  Where would data annotations be more suitable: ViewModels or Domain Objects or Both I am struggling to decide where these will be more suited. I have not as yet fully utilized them but this question came to mind. From most of the examples I have seen, they are generally placed on Models and simply use the required attributes for validation using ModelState.IsValid. I have also seen another question on SO where the use of data annotations alone is not sufficient and advocate. Option 1 - I will still need to validate again in my service layer. ( I think that my service layer should be complete and this include validation, since its planned to be used elsewhere) Option 2 - How will I then get the benefits of the built in validation both client and server side. Option 3 - there will be a repetition of validation logic, however I was wondering if one could use a MetaData class approach that can be used for both ViewModels and Domain Objects. ( This is completely of the top of my head, so it may be nonsensical) I wonder if this question even makes sense. If not, can someone please help in understanding this better. Have I completely misunderstood the use of data annotations?

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• Passing IDisposable objects through constructor chains

  - by Matt Enright

  I've got a small hierarchy of objects that in general gets constructed from data in a Stream, but for some particular subclasses, can be synthesized from a simpler argument list. In chaining the constructors from the subclasses, I'm running into an issue with ensuring the disposal of the synthesized stream that the base class constructor needs. Its not escaped me that the use of IDisposable objects this way is possibly just dirty pool (plz advise?) for reasons I've not considered, but, this issue aside, it seems fairly straightforward (and good encapsulation). Codes: abstract class Node { protected Node (Stream raw) { // calculate/generate some base class properties } } class FilesystemNode : Node { public FilesystemNode (FileStream fs) : base (fs) { // all good here; disposing of fs not our responsibility } } class CompositeNode : Node { public CompositeNode (IEnumerable some_stuff) : base (GenerateRaw (some_stuff)) { // rogue stream from GenerateRaw now loose in the wild! } static Stream GenerateRaw (IEnumerable some_stuff) { var content = new MemoryStream (); // molest elements of some_stuff into proper format, write to stream content.Seek (0, SeekOrigin.Begin); return content; } } I realize that not disposing of a MemoryStream is not exactly a world-stopping case of bad CLR citizenship, but it still gives me the heebie-jeebies (not to mention that I may not always be using a MemoryStream for other subtypes). It's not in scope, so I can't explicitly Dispose () it later in the constructor, and adding a using statement in GenerateRaw () is self-defeating since I need the stream returned. Is there a better way to do this? Preemptive strikes: yes, the properties calculated in the Node constructor should be part of the base class, and should not be calculated by (or accessible in) the subclasses I won't require that a stream be passed into CompositeNode (its format should be irrelevant to the caller) The previous iteration had the value calculation in the base class as a separate protected method, which I then just called at the end of each subtype constructor, moved the body of GenerateRaw () into a using statement in the body of the CompositeNode constructor. But the repetition of requiring that call for each constructor and not being able to guarantee that it be run for every subtype ever (a Node is not a Node, semantically, without these properties initialized) gave me heebie-jeebies far worse than the (potential) resource leak here does.

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• Saving owned/child objects in Hibernate

  - by maxdj

  I'm having a hard time wrapping my head around the way hibernate objects work. Here's a little chunk of what my model looks like: JobOpening: @ManyToMany(fetch=FetchType.EAGER,cascade=CascadeType.ALL) @JoinTable( name="jobOpening_questionSet", joinColumns=@JoinColumn(name="jobOpenings_id"), inverseJoinColumns=@JoinColumn(name="questionSets_id") ) @IndexColumn(name="question_sets_idx",base=0,nullable=false) public List<QuestionSet> getQuestionSets() { return questionSets; } QuestionSet: @ManyToMany(mappedBy="questionSets",fetch=FetchType.EAGER) public Set<JobOpening> getJobOpenings() { return jobOpenings; } @OneToMany(cascade=CascadeType.ALL,fetch=FetchType.EAGER) @IndexColumn(name="questions_idx",base=0) @JoinColumn(name="questionset_id",nullable=false) public List<FormQuestion> getQuestions() { return questions; } FormQuestion: @ManyToOne @JoinColumn(name="questionset_id", insertable=false, updatable=false, nullable=false) @OnDelete(action=OnDeleteAction.CASCADE) public QuestionSet getQuestionSet() { return questionSet; } Now how would I go about, say, modifying a question in the question set, or changing which jobs a questionset is associated with? For example, to edit a question in a questionset, I imagine I should be able to just get the question via its id, change some values, and merge() it back in, but this doesn't work. I'm using Hibernate from Spring (appfuse), usually as detached objects.

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• Overlapping 2 Flash objects and controlling z-index

  - by Magnus Smith

  I have two Flash objects on a webpage (call them A and B), and they overlap so one partially obscures the other. I don't seem to have any control over the z-index, to force B in front of A. Whatever I try, A always 'wins' and stays on the top! I have read many people's posts about problem with getting HTML to show over the top of Flash...but nothing about when your two overlapping items are both Flash objects. I have tried various combinations of wmode=opaque/transparent/window I have tried CSS position:absolute/relative and z-index:0/999 I have tried placing the HTML sections in a different order The problem is the same in IE6 and Firefox 2.0 I do not want to use jQuery in this case In my particular situation B must have position:absolute and wmode=transparent, and sit above A. A needs relative positioning and transparency is not required. However, I have been testing without these restrictions, and I still have no control over the overlap. Are some SWFs (ours are adverts sent by clients) created in such a way as to override any code control of z-index? Thanks for any advice you can give.

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• Passing data between objects in Chain of Responsibility pattern

  - by AbrahamJP

  While implementing the Chain of Responsibility pattern, i came across a dilemma om how to pass data between objects in the chain. The datatypes passed between object in the chain can differ for each object. As a temporary fix I had created a Static class containing a stack where each object in the chain can push the results to the stack while the next object in the chain could pop the results from the stack. Here is a sample code on what I had implemented. public interface IHandler { void Process(); } public static class StackManager { public static Stack DataStack = new Stack(); } //This class doesn't require any input to operate public class OpsA : IHandler { public IHandler Successor {get; set; } public void Process() { //Do some processing, store the result into Stack var ProcessedData = DoSomeOperation(); StackManager.DataStack.Push(ProcessedData); if(Successor != null) Successor(); } } //This class require input data to operate upon public class OpsB : IHandler { public IHandler Successor {get; set; } public void Process() { //Retrieve the results from the previous Operation var InputData = StackManager.DataStack.Pop(); //Do some processing, store the result into Stack var NewProcessedData = DoMoreProcessing(InputData); StackManager.DataStack.Push(NewProcessedData); if(Successor != null) Successor(); } } public class ChainOfResponsibilityPattern { public void Process() { IHandler ProcessA = new OpsA(); IHandler ProcessB = new OpsB(); ProcessA.Successor = ProcessB; ProcessA.Process(); } } Please help me to find a better approach to pass data between handlers objects in the chain.

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• Unable to persist objects in GAE JDO

  - by Basil Dsouza

  Hello Guys, I am completely fresh to both JDO and GAE, and have been struggling to get my data layer to persist any code at all! The issues I am facing may be very simple, but I just cant seem to find any a way no matter what solution I try. Firstly the problem: (Slightly simplified, but still contains all the info necessary) My data model is as such: User: (primary key) String emailID String firstName Car: (primary key) User user (primary key) String registration String model This was the initial datamodel. I implemented a CarPK object to get a composite primary key of the User and the registration. However that ran into a variety of issues. (Which i will save for another time/question) I then changed the design as such: User: (Unchanged) Car: (primary key) String fauxPK (here fauxPK = user.getEmailID() + SEP + registration) User user String registration String model This works fine for the user, and it can insert and retrieve user objects. However when i try to insert a Car Object, i get the following error: "Cannot have a java.lang.String primary key and be a child object" Found the following helpful link about it: http://stackoverflow.com/questions/2063467/persist-list-of-objects Went to the link suggested there, that explains how to create Keys, however they keep talking about "Entity Groups" and "Entity Group Parents". But I cant seem to find any articles or sites that explain what are "Entity Group"s or an "Entity Group Parents" I could try fiddling around some more to figure out if i can store an object somehow, But I am running sort on patience and also would rather understand and implement than vice versa. So i would appreciate any docs (even if its huge) that covers all these points, and preferably has some examples that go beyond the very basic data modeling. And thanks for reading such a long post :)

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• Bytecode and Objects

  - by HH

  Hey everyone, I am working on a bytecode instrumentation project. Currently when handling objects, the verifier throws an error most of the time. So I would like to get things clear concerning rules with objects (I read the JVMS but couldn't find the answer I was looking for): I am instrumenting the NEW instruction: original bytecode NEW <MyClass> DUP INVOKESPECIAL <MyClass.<init>> after instrumentation NEW <MyClass> DUP INVOKESTATIC <Profiler.handleNEW> DUP INVOKESPECIAL <MyClass.<init>> Note that I added a call to Profiler.handleNEW() which takes as argument an object reference (the newly created object). The piece of code above throws a VerificationError. While if I don't add the INVOKESTATIC (leaving only the DUP), it doesn't. So what is the rule that I'm violating? I can duplicate an uninitialized reference but I can't pass it as parameter? I would appreciate any help. Thank you

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• Python Tkinter comparing PhotoImage objects

  - by Kyle Schmidt

  In a simple LightsOut game, when I click on a light I need to toggle the image on a button. I'm doing this with Tkinter, so I thought I'd just check and see what image is currently on the button (either 'on.gif' or 'off.gif') and set it to the other one, like this: def click(self,x,y): if self.buttons[x][y].image == self.on: self.buttons[x][y].config(image=self.off) self.buttons[x][y].image == self.off else: self.buttons[x][y].config(image=self.on) self.buttons[x][y].image == self.on This ends up always being True - I can turn a lgiht off, but never turn it back on. Did some research, realized that I should probably be using cmp: def click(self,x,y): if cmp(self.buttons[x][y].image,self.on) == 0: self.buttons[x][y].config(image=self.off) self.buttons[x][y].image == self.off else: self.buttons[x][y].config(image=self.on) self.buttons[x][y].image == self.on But that gave me the exact same result. Both self.on and self.off are PhotoImage objects. Aside from keeping a separate set of lists which tracks what type of light is in each position and redrawing them every click, is there a way to directly compare two PhotoImage objects like this?

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• How to access valuestack objects within struts iterator?

  - by Monika Michael

  I have following code - <s:iterator value="reviews"> <img src="<s:property value="#request.restaurant.portalImage.url" />" /> <s:property value="user.firstName" /> <s:property value="user.lastName" /> <s:property value="rating" /> <s:property value="review" /> </s:iterator> reviews is a list of review objects which contain details of a review, such as rating and name of user. My problem is that i'm not able to access any of the objects present on the valuestack within the loop. Outside the loop <s:property value="#request.restaurant.portalImage.url" /> works correctly. But within the loop it prints null. AFAIK an iterator pushes it's collection on the valuestack so that all ognl expressions resolve against it. But I've used # which means I'm explicitly specifying the root object for resolution. Why is it still not working?

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• db4o problem with graph of objects

  - by Staszek28

  I am a new to db4o. I have a big problem with persistance of a graph of objects. I am trying to migrate from old persistance component to new, using db4o. Before I peristed all objects its graph looked like below (Take a look at Zrodlo.Metadane.abstrakt string field with focused value) [its view from eclipse debuger] with a code: ObjectContainer db=Db4o.openFile(DB_FILE); try { db.store(encja); db.commit(); } finally{ db.close(); } After that, I tried to read it with a code: ObjectContainer db=Db4o.openFile((DB_FILE)); try{ Query q = db.query(); q.constrain(EncjaDanych.class); ObjectSet<Object> objectSet = q.execute(); logger.debug("objectSet.size" + objectSet.size()); EncjaDanych encja = (EncjaDanych) objectSet.get(0); logger.debug("ENCJA" + encja.toString()); return encja; }finally{ db.close(); } and I got it (picture below) - string field "abstrakt" is null now !!! I take a look at it using ObjectManager (picture below) and abstrakt field has not-null value there!!! The same value, that on the 1st picture. Please help me :) It is my second day with db4o. Thanks in advance! I am attaching some code with structure of persisted class: public class EncjaDanych{ Map mapaIdRepo = new HashMap(); public Map mapaNazwaRepo = new HashMap(); }

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• Flex DataGridColumn with array of objects as data provider

  - by rforte

  I have a datagrid that uses an array of objects as the data provider. The objects are essentially key/value pairs: { foo:"something"} { bar:"hello"} { caca:"lorem"} The datagrid has 2 columns. The first column is the key and the second column is the value. Right now my grid looks like: My dataFormatter function makes sure that depending on the column (i.e. the dataField value) the correct key or value gets printed out. This works fine for displaying. However, as soon as I try and edit the value field it essentially adds a new value into the object with a key of '1'. For example, if I edit the {caca:"lorem"} object it will then contain the value {caca:"lorem",1:"new value"}. Is there any possible way I can set the DataGridColumn so that when I edit a value it will update the value associated with the key rather than inserting a new value? I've tried using a custom item editor but it still does the insert. It seems like I need to be able to update the 'dataField' with the actual key value but I'm not sure how to do that.

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• MySQL - Structure for Permissions to Objects

  - by Kerry

  What would be an ideal structure for users permissions of objects. I've seen many related posts for general permissions, or what sections a user can access, which consists of a users, userGroups and userGroupRelations or something of that nature. In my system there are many different objects that can get created, and each one has to be able to be turned on or off. For instance, take a password manager that has groups and sub groups. Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Group 8 Group 9 Group 10 Each group can contain a set of passwords. A user can be given read, write, edit and delete permissions to any group. More groups can get created at any point in time. If someone has permission to a group, I should be able to make him have permissions to all sub groups OR restrict it to just that group. My current thought is to have a users table, and then a permissions table with columns like: permission_id (int) PRIMARY_KEY user_id (int) INDEX object_id (int) INDEX type (varchar) INDEX read (bool) write (bool) edit (bool) delete (bool) This has worked in the past, but the new system I'm building needs to be able to scale rapidly, and I am unsure if this is the best structure. It also makes the idea of having someone with all subgroup permissions of a group more difficult. So, as a question, should I use the above structure? Or can someone point me in the direction of a better one?

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• Using pointers to adjust global objects in objective-c

  - by Rob

  Ok, so I am working with two sets of data that are extremely similar, and at the same time, these data sets are both global NSMutableArrays within the object. data_set_one = [[NSMutableArray alloc] init]; data_set_two = [[NSMutableArray alloc] init]; Two new NSMutableArrays are loaded, which need to be added to the old, existing data. These Arrays are also global. xml_dataset_one = [[NSMutableArray alloc] init]; xml_dataset_two = [[NSMutableArray alloc] init]; To reduce code duplication (and because these data sets are so similar) I wrote a void method within the class to handle the data combination process for both Arrays: -(void)constructData:(NSMutableArray *)data fromDownloadArray:(NSMutableArray *)down withMatchSelector:(NSString *)sel_str Now, I have a decent understanding of object oriented programming, so I was thinking that if I were to invoke the method with the global Arrays in the data like so... [self constructData:data_set_one fromDownloadArray:xml_dataset_one withMatchSelector:@"id"]; Then the global NSMutableArrays (data_set_one) would reflect the changes that happen to "array" within the method. Sadly, this is not the case, data_set_one doesn't reflect the changes (ex: new objects within the Array) outside of the method. Here is a code snippet of the problem // data_set_one is empty // xml_dataset_one has a few objects [constructData:(NSMutableArray *)data_set_one fromDownloadArray:(NSMutableArray *)xml_dataset_one withMatchSelector:(NSString *)@"id"]; // data_set_one should now be xml_dataset_one, but when echoed to screen, it appears to remain empty And here is the gist of the code for the method, any help is appreciated. -(void)constructData:(NSMutableArray *)data fromDownloadArray:(NSMutableArray *)down withMatchSelector:(NSString *)sel_str { if ([data count] == 0) { data = down; // set data equal to downloaded data } else if ([down count] == 0) { // download yields no results, do nothing } else { // combine the two arrays here } } This project is not ARC enabled. Thanks for the help guys! Rob

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• Python: Errors saving and loading objects with pickle module

  - by Peterstone

  Hi, I am trying to load and save objects with this piece of code I get it from a question I asked a week ago: Python: saving and loading objects and using pickle. The piece of code is this: class Fruits: pass banana = Fruits() banana.color = 'yellow' banana.value = 30 import pickle filehandler = open("Fruits.obj","wb") pickle.dump(banana,filehandler) filehandler.close() file = open("Fruits.obj",'rb') object_file = pickle.load(file) file.close() print(object_file.color, object_file.value, sep=', ') At a first glance the piece of code works well, getting load and see the 'color' and 'value' of the saved object. But, what I pursuit is to close a session, open a new one and load what I save in a past session. I close the session after putting the line filehandler.close() and I open a new one and I put the rest of your code, then after putting object_file = pickle.load(file) I get this error: Traceback (most recent call last): File "<pyshell#5>", line 1, in <module> object_file = pickle.load(file) File "C:\Python31\lib\pickle.py", line 1365, in load encoding=encoding, errors=errors).load() AttributeError: 'module' object has no attribute 'Fruits' Can anyone explain me what this error message means and telling me how to solve this problem? Thank so much and happy new year!!

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• Delphi: Transporting Objects to remote computers

  - by pr0wl

  Hallo. I am writing a tier2 ordering software for network usage. So we have client and server. On the client I create Objects of TBest in which the Product ID, the amount and the user who orders it are saved. (So this is a item of an Order). An order can have multiple items and those are saved in an array to later send the created order to the server. The class that holds the array is called TBestellung. So i created both TBest.toString: string; and TBest.fromString(source: string): TBest; Now, I send the toString result to the server via socket and on the server I create the object using fromString (its parsing the attributes received). This works as intended. Question: Is there a better and more elegant way to do that? Serialisation is a keyword, yes, but isn't that awful / difficult when you serialize an object (TBestellung in this case) that contains an Array of other Objects (TBest in this case)? //Small amendment: Before it gets asked. Yes I should create an extra (static) class for toString and fromString because otherwise the server needs to create an "empty" TBest in order to be able to use fromString.

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• Hundreds of custom UserControls create thousands of USER Objects

  - by Andy Blackman

  I'm creating a dashboard application that shows hundreds of "items" on a FlowLayoutPanel. Each "item" is a UserControl that is made up of 12 or labels. My app queries a database and then creates an "item" instance for each record, populating ethe labels and textboxes with data before adding it to the FlowLayoutPanel. After adding about 560 items to the panel, I noticed that the USER Objects count in my Task Manager had gone up to about 7300, which was much much larger than any other app on my machine. I did a quick spot of mental arithmetic (OK, I might have used calc.exe) and figured that 560 * 13 (12 labels plus the UserControl itself) is 7280. So that suddenly gave away where all the objects were coming from... Knowing that there is a 10,000 USER object limit before windows throws in the towel, I'm trying to figure better ways of drawing these items onto the FlowLayoutPanel. My ideas so far are as follows: 1) User-draw the "item", using graphics.DrawText and DrawImage in place of many of the labels. I'm hoping that this will mean 1 item = 1 USER Object, not 13. 2) Have 1 instance of the "item", then for each record, populate the instance and use the Control.DrawToBitmap() method to grab an image and then use that in the FlowLayoutPanel (or similar) So... Does anyone have any other suggestions ??? P.S. It's a zoomable interface, so I have already ruled out "Paging" as there is a requirement to see all items at once :( Thanks everyone.

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• Howto use predicates in LINQ to Entities for Entity Framework objects

  - by user274947

  I'm using LINQ to Entities for Entity Framework objects in my Data Access Layer. My goal is to filter as much as I can from the database, without applying filtering logic on in-memory results. For that purpose Business Logic Layer passes a predicate to Data Access Layer. I mean Func<MyEntity, bool> So, if I use this predicate directly, like public IQueryable<MyEntity> GetAllMatchedEntities(Func<MyEntity, Boolean> isMatched) { return qry = _Context.MyEntities.Where(x => isMatched(x)); } I'm getting the exception [System.NotSupportedException] --- {"The LINQ expression node type 'Invoke' is not supported in LINQ to Entities."} Solution in that question suggests to use AsExpandable() method from LINQKit library. But again, using public IQueryable<MyEntity> GetAllMatchedEntities(Func<MyEntity, Boolean> isMatched) { return qry = _Context.MyEntities.AsExpandable().Where(x => isMatched(x)); } I'm getting the exception Unable to cast object of type 'System.Linq.Expressions.FieldExpression' to type 'System.Linq.Expressions.LambdaExpression' Is there way to use predicate in LINQ to Entities query for Entity Framework objects, so that it is correctly transformed it into a SQL statement. Thank you.

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• Will WCF allow me to use object references across boundries on objects that implement INotifyPropert

  - by zimmer62

  So I've created a series of objects that interact with a piece of hardware over a serial port. There is a thread running monitoring the serial port, and if the state of the hardware changes it updates properties in my objects. I'm using observable collections, and INotifyPropertyChanged. I've built a UI in WPF and it works great, showing me real time updating when the hardware changes and allows me to send changes to the hardware as well by changing these properties using bindings. What I'm hoping is that I can run the UI on a different machine than what the hardware is hooked up to without a lot of wiring up of events. Possibly even allow multiple UI's to connect to the same service and interact with this hardware. So far I understand I'm going to need to create a WCF service. I'm trying to figure out if I'll be able to pass a reference to an object created at the service to the client leaving events intact. So that the UI will really just be bound to a remote object. Am I moving the right direction with WCF? Also I see tons of examples for WCF in C#, are there any good practical use examples in VB that might be along the lines of what I'm trying to do?

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• C# array of objects - conditional validation

  - by fishdump

  Sorry about the vague title! I have an class with a number of member variables (system, zone, site, ...) public sealed class Cello { public String Company; public String Zone; public String System; public String Site; public String Facility; public String Process; //... } I have an array of objects of this class. private Cello[] m_cellos = null; // ... I need to know whether the array contains objects with the same site but different systems, zones or companies since such a situation would be illegal. I have various other checks to make but they are all along similar lines. The Array class has a number of functions that look promising but I am not very up on defining 'key selector' functions and things like that. Any suggestions or pointers would be greatly appreciated. --- Alistair.

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• Storing large numbers of varying size objects on disk

  - by Foredecker

  I need to develop a system for storing large numbers (10's to 100's of thousands) of objects. Each object is email-like - there is a main text body, and several ancillary text fields of limited size. A body will be from a few bytes, to several KB in size. Each item will have a single unique ID (probably a GUID) that identifies it. The store will only be written to when an object is added to it. It will be read often. Deletions will be rare. The data is almost all human readable text so it will be readily compressible. A system that lets me issue the I/Os and mange the memory and caching would be ideal. I'm going to keep the indexes in memory, using it to map indexes to the single (and primary) key for the objects. Once I have the key, then I'll load it from disk, or the cache. The data management system needs to be part of my application - I do not want to depend on OS services. Or separately installed packages. Native (C++) would be best, but a manged (C#) thing would be ok. I believe that a database is an obvious choice, but this needs to be super-fast for look up and loading into memory of an object. I am not experienced with data base tech and I'm concerned that general relational systems will not handle all this variable sized data efficiently. (Note, this has nothing to do with my job - its a personal project.) In your experience, what are the viable alternatives to a traditional relational DB? Or would a DB work well for this?

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• What type of objects can be sent back to an action Method using HTML.HIDDEN()

  - by Richard77

  Hello, 1)Let's say I've this form: <%Using(Html.BeginForm()){%> <% = Html.Hidden("myObject", (cast to the appropriate type)ViewData["KeyForMyObject"]%> <input type = "submit" "Submit Object"> <%}%> 2) Here's the Action which's supposed to intercept the value of the object public ActionResult MyAction(Type myObject) { //Do Something with the object } Here's my question: What type of objects the Hidden field can support? In fact, when ViewData["KeyForMyObject"] contains a string, int, or bool, myAction is able to retrieve the value. But, when it comes to objects, such as List, and dictionary, nothing happens. When I debug to check the local values, I see null for Type myObject in the MyMethod. So what are the rules in MVC when it comes to a List or Dictionary? ================================= EDIT To make things simpler, can I write something like this <% = Html.Hidden("contactDic", (Dictionary<string, string>) ViewData["contacts"])%> and expect to retrieve the dictionary in the action Method like this public ActionResult myMethod(Dictionary<string, string> contactDic) { //Do something with the dictionary } Thanks for Helping

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• Best method to cache objects in PHP?

  - by Martin Bean

  Hi, I'm currently developing a large site that handles user registrations. A social networking website for argument's sake. However, I've noticed a lag in page loads and deciphered that it is the creation of objects on pages that's slowing things down. For example, I have a Member object, that when instantiated with an ID passed as a construct parameter, it queries the database for that members' row in the members database table. Not bad, but this is created each time a page is loaded; and called more than once when say, calling an array of that particular members' friends, as a new Member object is created for each friend. So on a single page I can have upwards of seven of the same object, but containing different properties. What I'm wanting to do is to find a way to reduce the database load, and to allow persist objects between page loads. For example, the logged in user's object to be created on login (which I can do) but then stored somewhere for retrieval so I don't have to keep re-creating the object between page loads. What is the best solution for this? I've had a look at Memcache, but with it being a third-party module I can't have the web host install it on this occasion. What are my alternatives, and/or best practices in my case? Thanks in advance.

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• Prevent cached objects to end up in the database with Entity Framework

  - by Dirk Boer

  We have an ASP.NET project with Entity Framework and SQL Azure. A big part of our data only needs to be updated a few times a day, other data is very volatile. The data that barely changes we cache in memory at startup, detach from the context and than use it mainly for reading, drastically lowering the amount of database requests we have to do. The volatile data is requested everytime by a DbContext per Http request. When we do an update to the cached data, we send a message to all instances to catch a fresh version of all the data from the SQL server. So far, so good. Until we introduced a bug that linked one of these 'cached' objects to the 'volatile' data, and did a SaveChanges. Well, that was quite a mess. The whole data tree was added again and again by every update, corrupting the whole database with a whole lot of duplicated data. As a complete hack I added a completely arbitrary column with a UniqueConstraint and some gibberish data on one of the root tables; hopefully failing the SaveChanges() next time we introduce such a bug because it will violate the Unique Constraint. But it is of course hacky, and I'm still pretty scared ;P Are there any better ways to prevent whole tree's of cached objects ending up in the database? More information Project is ASP.NET MVC I cache this data, because it is mainly read only, and this saves a tons of extra database calls per http request

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