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  • What should layers in dotnet application ?

    - by haansi
    I am using layered architecture in dotnet (mostly I work on web projects). I am confuse what layers should I use ? I have small idea that there should be the following layers. user interface customer types (custom entities) business logic layer data access layer My purpose is sure quality of work and maximum re-usability of code. some one suggested to add common types layer in it. Please guide me what should be layers ? and in each layer what part should go ?

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  • Finding the specific type held in an ArrayList<Object> (ie. Object = String, etc.)

    - by Christopher Griffith
    Say I have an ArrayList that I have cast to an ArrayList of objects. I know that all the objects that were in the ArrayList I cast were of the same type, but not what the type was. Now, if the ArrayList is not empty, I could take one of the objects in it and use the instanceof operator to learn what the actual type is. But what of the case where the ArrayList is empty? How do I determine what type Object actually is then? Is it possible?

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  • Save objects to a database?

    - by Eric
    So far in my .Net coding adventures I've only had a need to save information to files. So I've used XmlSerializer and DataContractSerializer to serialize attributed classes to XML files. My next project, however, requires that I save and retrieve information from a SQL server database. I'm wondering what my options are for doing this. The current version of the app, which was not created by me, uses a lot of hard coded SQL commands. But now I'm trying to avoid doing anything where I have to read or write individual fields to or from the database or objects. I especially want to avoid a lot of hard coded SQL in my code. I like how the serializer classes just figure out how to read and write XML files based on the attributes and or public properties of the class. Is there something similar for a database rather then XML?

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  • benefit of having a factory for object creation?

    - by ajsie
    I'm trying to understand the factory design pattern. I don't understand why it's good to have a middleman between the client and the product (object that the client wants). example with no factory: $mac = new Mac(); example with a factory: $appleStore = new AppleStore(); $mac = $appleStore->getProduct('mac'); How does the factory pattern decouple the client from the product? Could someone give an example of a future code change that will impact on example 1 negative, but positive in example 2 so I understand the importance of decoupling? Thanks.

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  • Sharing class member data between sub components

    - by Tim Gradwell
    I have an aggregate 'main' class which contains some data which I wish to share. The main class also has other class members. I want to share the data with these other class members. What is the correct / neatest way to do this? The specific example I have is as follows. The main class is a .net Form. I have some controls (actually controls within controls) on the main form which need access to the shared data. Main Form - DataX - DataY - Control1 -- Subcontrol1 - Control2 -- SubControl2 SubControls 1 and 2 both wish to access DataX and DataY. The trouble is, I feel like better practice (to reduce coupling), would be that either subcontrols should not know about Main Form, or Main Form should not know about subcontrols - probably the former. For subcontrols not to know about Main Form, would probably mean Main Form passing references to both Controls 1 and 2, which in turn would pass the references on to SubControls 1 and 2. Lots of lines of code which just forward the references. If I later added DataZ and DataW, and Controls 3 and 4 and SubControls 3 and 4, I'd have to add lots more reference forwarding code. It seems simpler to me to give SubControls 1 and 2 member references to Main Form. That way, any sub control could just ask for MainForm.DataX or MainForm.DataY and if I ever added new data, I could just access it directly from the sub controls with no hassle. But it still involves setting the 'MainForm' member references every time I add a new Control or Subcontrol. And it gives me a gut feeling of 'wrong'. As you might be able to tell I'm not happy with either of my solutions. Is there a better way? Thanks

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  • Avoiding sub-type selection in view code

    - by John Donoghue
    Hi, I have some code where the model contains some classes like (vb.net pseudocode, but could be any OO language): Enum AttributeType Boolean Date String End Enum MustInherit Class Attibute Must Override Function Type As AttributeType End Class Class BooleanAttribute: Attribute Function Type As AttributeType Return AttributeType.Boolean End Function End Class And the view contains some code like: Select Case AttributeType Case Boolean //Display checkbox control Case Date //Display date picker control Case String //Display textbox control End Select I don't really like the code in the view, for the hopefully obvious reasons (what happens when I get a new attribute type etc). My question is, how should I replace it? I could easily add a method to the concrete classes, but that pollutes the model with UI stuff so that's a horrible idea. I could move the select into a factory, but that seems to be just hiding the problem. Can anybody advise a better approach?

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  • How to delete object with a mouse click ?

    - by Meko
    Hi all. I made a simple FlowChat Editor that creates rectangles and triangles and connects them to each other and shows the way from up to down. I can move this elements on screen too. I am now trying to create a button to delete the element which I clicked. There is problem that I can delete MyTriangle objects, but I can't delete MyRectangle objects. It deletes but not object which I clicked. I delete from first object to last. Here is my code: if (deleteObj) { if (rectsList.size() != 0) { for (int i = 0; i < rectsList.size(); i++) { MyRect rect = (MyRect) rectsList.get(i); if (e.getX() <= rect.c.x + 50 && e.getX() >= rect.c.x - 50 && e.getY() <= rect.c.y + 15 && e.getY() >= rect.c.y - 15) { rectsList.remove(rect); System.out.println("This is REctangle DELETED\n"); } } } if (triangleList.size() != 0) { for (int j = 0; j < triangleList.size(); j++) { MyTriangle trian = (MyTriangle) triangleList.get(j); if (e.getX() <= trian.c.x + 20 && e.getX() >= trian.c.x - 20 && e.getY() <= trian.c.y + 20 && e.getY() >= trian.c.y - 20) { triangleList.remove(trian); System.out.println("This is Triangle Deleted\n"); } } } Edit Here MyRectangle and MyTriangle classes public class MyRect extends Ellipse2D.Double { Point c; Point in; Point out; int posX; int posY; int width = 100; int height = 30; int count; public MyRect(Point center, Point input, Point output,int counter) { c = center; in = input; out = output; count=counter; } void drawMe(Graphics g) { // in.x=c.x+20; int posX = c.x; int posY = c.y; int posInX = in.x; int posInY = in.y; int posOutX = out.x; int posOutY = out.y; g.setColor(Color.MAGENTA); g.drawString(" S "+count ,posX-5, posY+5); g.setColor(Color.black); g.drawRect(posX-50, posY-15, width, height); g.setColor(Color.green); g.drawRect(posInX-3, posInY-9, 6, 6); g.setColor(Color.blue); g.drawRect(posOutX-3, posOutY+3, 6, 6); } } public class MyTriangle { Point c; Point in ; Point outYES ; Point outNO ; int posX; int posY; int count; public MyTriangle(Point center,Point input,Point outputYES,Point outputNO,int counter) { c = center; in = input; outYES = outputYES; outNO = outputNO; count=counter; } void drawMe(Graphics g) { int posX = c.x; int posY = c.y; int posInX=in.x; int posInY=in.y; int posOutYESX=outYES.x; int posOutYESY=outYES.y; int posOutNOX=outNO.x; int posOutNOY=outNO.y; int[] xPoints = {posX - 50, posX, posX + 50, posX}; int[] yPoints = {posY, posY - 30, posY, posY + 30}; g.setColor(Color.MAGENTA); g.drawString(" T "+count,posX-5, posY+5); g.setColor(Color.black); g.drawPolygon(xPoints, yPoints, 4); // draw input g.setColor(Color.green); g.drawRect(posInX-3,posInY-9, 6, 6); g.setColor(Color.blue); g.drawRect(posOutYESX-9,posOutYESY-3 , 6, 6); g.setColor(Color.red); g.drawRect(posOutNOX-3,posOutNOY+3 , 6, 6); } }

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  • Class with proprties that haven't been set

    - by koumides
    Hello there, I am creating a class in C# which eventually will be part of a library that other uses can use. A user of this class has to set some properties and then use a public method to retrieve the results. What shall I do when a user calls the method without setting all the properties? Throw exception and expect the user to catch it? Thanks

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  • Separating code logic from the actual data structures. Best practices?

    - by Patrick
    I have an application that loads lots of data into memory (this is because it needs to perform some mathematical simulation on big data sets). This data comes from several database tables, that all refer to each other. The consistency rules on the data are rather complex, and looking up all the relevant data requires quite some hashes and other additional data structures on the data. Problem is that this data may also be changed interactively by the user in a dialog. When the user presses the OK button, I want to perform all the checks to see that he didn't introduce inconsistencies in the data. In practice all the data needs to be checked at once, so I cannot update my data set incrementally and perform the checks one by one. However, all the checking code work on the actual data set loaded in memory, and use the hashing and other data structures. This means I have to do the following: Take the user's changes from the dialog Apply them to the big data set Perform the checks on the big data set Undo all the changes if the checks fail I don't like this solution since other threads are also continuously using the data set, and I don't want to halt them while performing the checks. Also, the undo means that the old situation needs to be put aside, which is also not possible. An alternative is to separate the checking code from the data set (and let it work on explicitly given data, e.g. coming from the dialog) but this means that the checking code cannot use hashing and other additional data structures, because they only work on the big data set, making the checks much slower. What is a good practice to check user's changes on complex data before applying them to the 'application's' data set?

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  • Get next key-value pair in an object

    - by captainclam
    So, given a key, I want to find the next property in an object. Then, I want to return the value of the NEXT property. I can not rely on the keys to be ordered or sequential (they're uuids). Please see below for trivial example of what I want: var db ={ a: 1, b: 2, c: 3 } var next = function(db, key) { // ??? } next(db, 'a'); // I want 2 next(db, 'b'); // I want 3 I also want a prev() function, but I'm sure it will be the same solution. This seems like such a trivial problem but I can't for the life of me figure out how to do it. Happy for the solution to use underscore.js or be written in coffeescript :)

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  • Casting an object which could be null

    - by DeeMac
    DateTime? testDate = (DateTime?)arrayOfObjects[dateObject]; Does that code look ok? I attempted to use the as operator but I got the 'non-nullable' error. What I'm trying to say is that the object I'm choosing from the array is either DateTime or a null DateTime but either can be assigned to testDate. Doesn't feel right doing it this way, I think I'm missing something obvious. EDIT: I suppose it's the same as the way I could've adapted the as in the following way: DateTime? testDate = arrayOfObjects[dateObject] as DateTime?; Is either line of code the best way of handling potential nulls?

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  • Ruby: Streaming large AWS S3 object freezes

    - by Peter
    Hi, I am using the ruby aws/s3 library to retrieve files from Amazon S3. I stream an object and write it to file as per the documentation (with debug every 100 chunks to confirm progress) This works for small files, but randomly freezes downloading large (150MB) files on VPS Ubuntu. Fetching the same files (150MB) from my mac on a much slower connection works just fine. When it hangs there is no error thrown and the last line of debug output is the 'Finished chunk'. I've seen it write between 100 and 10,000 chunks before freezing. Anyone come across this or have ideas on what the cause might be? Thanks The code that hangs: i=1 open(local_file, 'w') do |f| AWS::S3::S3Object.value(key, @s3_bucket) do |chunk| puts("Writing chunk #{i}") f.write chunk.read_body puts("Finished chunk #{i}") i=i+1 end end

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  • Object for storing strings in Python

    - by evg
    class MyWriter: def __init__(self, stdout): self.stdout = stdout self.dumps = [] def write(self, text): self.stdout.write(smart_unicode(text).encode('cp1251')) self.dumps.append(text) def close(self): self.stdout.close() writer = MyWriter(sys.stdout) save = sys.stdout sys.stdout = writer I use self.dumps list to store data obtained from prints. Is there a more convenient object for storing string lines in memory? Ideally I want dump it to one big string. I can get it like this "\n".join(self.dumps) from code above. May be it's better to just concatenate strings - self.dumps += text?

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  • Accessing object's method within string

    - by Wild One
    Recently I was reading php documentation and found interesting note in string section: Functions, method calls, static class variables, and class constants inside {$} work since PHP 5. However, the value accessed will be interpreted as the name of a variable in the scope in which the string is defined. Using single curly braces ({}) will not work for accessing the return values of functions or methods or the values of class constants or static class variables. See www.php.net/manual/en/language.types.string.php It says, that I can't use curly syntax to get value returned by object's method call. Is it a mistake in manual or I misunderstood it, because I tried the following code and it works just fine: <?php class HelloWorld { public static function hello() { echo 'hello'; } } $a = new HelloWorld(); echo "{$a->hello()} world";

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  • How can I call a Perl package I define in the same file?

    - by Robert S. Barnes
    I need to define some modules and use them all in the same file. No, I can't change the requirement. I would like to do something like the following: { package FooObj; sub new { ... } sub add_data { ... } } { package BarObj; use FooObj; sub new { ... # BarObj "has a" FooObj my $self = ( myFoo => FooObj->new() ); ... } sub some_method { ... } } my $bar = BarObj->new(); However, this results in the message: Can't locate FooObj.pm in @INC ... BEGIN failed... How do I get this to work?

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  • Java ME Runnable object takes up memory although not made an instance yet

    - by user1646684
    I am facing a strange problem with memory in Java ME. here is a part of my code: int variable=1; while (true) { if (variable==2) { display = Display.getDisplay(this); MyCanvas mc = new MyCanvas(this); // MyCanvas is a runnable object mcT = new Thread(mc); // new thread for MyCanvas mc.repaint(); display.setCurrent(mc); mcT.start(); // run thread } if (variable==1) { // Do some other stuff } } The problem is that although still the variable is set to 1, so it does not come through the if (variable==2) condition the program consumes 300kB more memory than when I delete the code after condition if (variable==2). As far as I know the code should by executed and the objects shall be created only when I set variable to value 2. But it consumes the memory also when the code after condition "if (variable==2)" is not executed. Why does this happen?

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  • Iterating through facebook comments JSON object failing

    - by user1594304
    I tried the option of students.item["http://www.myurl.com"].comments.data.length. However, the item["http://www.myurl.com"] call is not working. If I take out the URL from JSON object and write the iterator with students.comments.data, it works. Here is my code, any help highly appreciated. var students = { "http://www.myurl.com":{ "comments":{ "data" : [ { "id": "123456778", "from": { "name": "XYZ", "id": "1000005" }, "message": "Hey", "can_remove": false, "created_time": "2012-09-03T03:16:01+0000", "like_count": 0, "user_likes": false } ] } } } var i=0 var arrayObject = new Array(); alert("Parsing 2: "+students.item["http://www.myurl.com"].comments.data.length); for(i=0;i<students.item["http://www.myurl.com"].comments.data.length;i++) { alert("Parsing 1: "+i); arrayObject.push(students.item["http://www.myurl.com"].comments.data[i].id); arrayObject.push(students.item["http://www.myurl.com"].comments.data[i].message); arrayObject.push(students.item["http://www.myurl.com"].comments.data[i].created_time); }

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  • Returning an array from an activity

    - by Boardy
    I am currently working on an android project and I want to be able to startActivityForResult so that I can return an array of. The array is an ArrayList<Spanned> lets say its called myArray. From what I've read I can't return an array directly from the activty using the set result so I was thinking that once the array has added all the data to the array, I can then call the toString function on it, i.e. myArray.toString(). If I do this, I have no idea how I can then convert this back into the original ArrayList<Spanned>. Thanks for any help you can provide.

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  • In what package should a "Settings" class be placed?

    - by Tom
    I'm in the middle of building an application but found myself too easily creating new packages without keeping the project's structure in mind. Now, I'm trying to redo the whole project structure on paper first. I am using a Settings class with public properties, accessed as settings for several other classes around the project. Now, since this Settings class applies for the whole project, I am unsure if it should be packaged and if so, in what kind of package should it exist? Or should it be in the root (the default package) with the main application class? I've been thinking about putting it in my utils package, then again I don't think it really is an utlity. Any strategies on how to decide on such package structure for example for a Settings class?

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  • Creating non-framework calsses in CakePHP

    - by Affian
    I'm making a tournament manager in CakePHP 1.3 and I have a tournament controller which is fine but I want to implement a interface that can be used to define how a tournament runs. the controller needs to load a concrete class that implements the TournamentStyle interface that defines how the tournament works. At the end of a round the TournamentStyle is used to calculate the scores and winners and generate the next round of matches. That gives me a .php file for the interface and other files for the various styles. My question is: where would I put these files and how would I load them into my tournament controller?

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  • What is the right way to implement communication between java objects?

    - by imoschak
    I'm working on an academic project which simulates a rather large queuing procedure in java. The core of the simulator rests within one package where there exist 8 classes, each one implementing a single concept. Every class in the project follows SRP. These classes encapsulate the behavior of the simulator and inter-connect every other class in the project. The problem that has arisen is that most of these 8 classes are, as is logical i think, tightly coupled and each one has to have working knowledge of every other class in this package in order to be able to call methods from it when needed. The application needs only one instance of each class so it might be better to create static fields for each class in a new class and use that to make calls -instead of preserving a reference in each class for every other class in the package (which I'm certain that is incorrect)-, but is this considered a correct design solution? or is there a design pattern maybe that better suits my needs?

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  • Encapsulating a Windows.Forms.Button

    - by devoured elysium
    I want to define a special kind of button that only allows two possible labels: "ON" and "OFF". I decided to inherit from a Windows.Forms.Button to implement this but now I don't know I how should enforce this rule. Should I just override the Text property like this? public override string Text { set { throw new InvalidOperationException("Invalid operation on StartStopButton!"); } } The problem I see with this is that I am breaking the contract that all buttons should have. If any code tries something like foreach (Button button in myForm) { button.Text = "123"; } they will get an Exception if I have any of my special buttons on the form, which is something that isn't expectable. First, because people think of properties just as "public" variables, not methods, second, because they are used to using and setting whatever they want to buttons without having to worry with Exceptions. Should I instead just make the set property do nothing? That could also lead to awkward results: myButton.Text = "abc"; MessageBox.Show(abc); //not "abc"! The general idea from the OO world is to in this kind of cases use Composition instead of inheritance. public class MySpecialButton : <Some class from System.Windows.Forms that already knows how to draw itself on forms> private Button button = new Button(); //I'd just draw this button on this class //and I'd then only show the fields I consider //relevant to the outside world. ... } But to make the Button "live" on a form it must inherit from some special class. I've looked on Control, but it seems to already have the Text property defined. I guess the ideal situation would be to inherit from some kind of class that wouldn't even have the Text property defined, but that'd have position, size, etc properties available. Upper in the hierarchy, after Control, we have Component, but that looks like a really raw class. Any clue about how to achieve this? I know this was a long post :( Thanks

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