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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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• 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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• Databinding a list (in an object) to a combobox in VB.net

  - by Casey

  VB 2008 .NET 3.5 I have a custom "Shipment" object that contains a list of "ShippingRate" objects. This list of "ShippingRates" is accessible through a property "Shipment.PossibleShippingRates." That property simply returns a copy of the list of "ShippingRate" for that particular Shipment. My UI layer receives a list of "Shipment" objects from the BLL. This list is databound to a datagridview, and shows details relevant to the Shipment such as Shipping Address, etc. I want to bind the "Shipment.PossibleShippingRates" property to a combobox, such that when the user changes the grid row, the combobox reflects the "PossibleShippingRates" for that "Shipment." In addition, I need a way to store the "ShippingRate" they selected from the combobox for later use. I have tried a few ideas, but none of them work properly. Any ideas on how to do this?

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• How to relate keywords to records - Many to Many

  - by webworm

  Hi All, I am looking for suggestions on database design for a sample jobs listing application. I have many jobs that I would like to associate various keywords with. Each job can have multiple keywords. I would like to store the keywords in a seperate table instead of in a field within the Job table so as to avoid mispellings in keywords. What is the best way to relate keywords to the jobs? I was thinking of using an intermediary table that would have a many to many relationship linking keywords to jobs. Is this the best way to go or should I just have a field in the Job table that contains multiple keywords? Thanks for any suggestions.

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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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• Trying to re-create UI object from the native iPhone Calendar Notes

  - by FrankOS

  Probably a lame question for a start but i'm trying to re-create the ui object that's used in Apple's native Calendar to create notes. It's the basic text-field but with multiple lines. Sort of a text-area. Now i know that anything from the calendar in terms of ui objects isn't available but i have seen this in quite few apps so i'm guessing it's some sort of standard component. I must be dumb but i just cannot find it. Help please... Thx :)

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• Where do you find images and graphics designers for your softwares ?

  - by ereOn

  Hi, As a programmer, I'm sure some of you already experienced the same problem: You create a good software (free, open-source, or for friend-only diffusion, whatever) relying on good code and good ideas but since you're a programmer and not an image designer, your program looks just bad. While it seems pretty easy to find motivated developpers to join for free an open-source project, it seems quite hard to find a single free graphic designer. What free and good resources do you usually use for your programs/websites ? Do you have any cool tip that you're willing to share ? Do you know any place where to find people involved into graphic design willing to participate to open-source projects ?

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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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• Exception in Google App Engine (Java) while trying to create Memcache Object

  - by Shreeni

  I am coming back to an old Google App Engine project on which I saw a bug. During this lag, I have been upgrading my AppEngine SDK and is now set at 1.3. When I try to run the same project again, I see the following exception: java.lang.NoSuchMethodError: com.google.apphosting.api.ApiProxy$Environment.getDefaultNamespace()Ljava/lang/String; at com.google.appengine.api.NamespaceManager.get(NamespaceManager.java:56) at com.google.appengine.api.memcache.MemcacheServiceImpl.setNamespace(MemcacheServiceImpl.java:181) at com.google.appengine.api.memcache.MemcacheServiceImpl.(MemcacheServiceImpl.java:145) at com.google.appengine.api.memcache.MemcacheServiceFactory.getMemcacheService(MemcacheServiceFactory.java:25) The line causing the problem is: CacheManager.getInstance().getCacheFactory().createCache(Collections.emptyMap()); (It is the same line as suggested by the AppEngine documentation to create a memcache object. It used to work fine previously. ) Any suggestions on how to fix it?

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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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• declare field without initial value in php?

  - by Charles

  I don't want to give an initial value. I want to set these later using the set method class Duck { var int id; var set = Array(); } Any idea how to declare without getting error?

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• Singletons and constants

  - by devoured elysium

  I am making a program which makes use of a couple of constants. At first, each time I needed to use a constant, I'd define it as //C# private static readonly int MyConstant = xxx; //Java private static final int MyConstant = xxx; in the class where I'd need it. After some time, I started to realise that some constants would be needed in more than one class. At this time, I had 3 choises: To define them in the different classes that needed it. This leads to repetition. If by some reason later I need to change one of them, I'd have to check in all classes to replace them everywhere. To define a static class/singleton with all the constants as public. If I needed a constant X in ClassA, ClassB and ClassC, I could just define it in ClassA as public, and then have ClassB and ClassC refer to them. This solution doesn't seem that good to me as it introduces even more dependencies as the classes already have between them. I ended up implementing my code with the second option. Is that the best alternative? I feel I am probably missing some other better alternative. What worries me about using the singleton here is that it is nowhere clear to a user of the class that this class is using the singleton. Maybe I could create a ConstantsClass that held all the constants needed and then I'd pass it in the constructor to the classes that'd need it? Thanks

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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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• Dynamic class_name for has_many relations

  - by vooD

  I'm trying to make has_many relation with dynamic class_name attribute class Category < ActiveRecord::Base has_many :ads, :class_name => ( lambda { return self.item_type } ) end or class Category < ActiveRecord::Base has_many :ads, :class_name => self.item_type end But i got errors: can't convert Proc into String or undefined method `item_type' for #<Class:0xb62c6c88> Thank you for any help!

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• Write a tree class in Java where each level has a unique object type

  - by user479576

  I need to write a tree class in Java where each level has a unique object type. The way it is written below does not take advantage of generics and causes alot of duplicate code. Is there a way to write this with Generics ? public class NodeB { private String nodeValue; //private List<NodeB> childNodes; // constructors // getters/setters } public class NodeA { private String value; private List<NodeB> childNodes; // constructors // getters/setters } public class Tree { private String value; private List<NodeA> childNodes; // constructors // tree methods }

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• What is so special about Smalltalk?

  - by Steve

  In every technical publication, and on this site too, people are always comparing OO languages to Smalltalk. My experience is in Java: is Smalltalk so important that I should study it?

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• Any method to denote object assignment?

  - by Droogans

  I've been studying magic methods in Python, and have been wondering if there's a way to outline the specific action of: a = MyClass(*params).method() versus: MyClass(*params).method() In the sense that, perhaps, I may want to return a list that has been split on the '\n' character, versus dumping the raw list into the variable a that keeps the '\n' intact. Is there a way to ask Python if its next action is about to return a value to a variable, and change action, if that's the case? I was thinking: class MyClass(object): def __init__(*params): self.end = self.method(*params) def __asgn__(self): return self.method(*params).split('\n') def __str__(self): """this is the fallback if __asgn__ is not called""" return self.method(*params)

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• Elegant ways of displaying a GridView with lots of columns (ASP.NET)

  - by Chris

  Hi, just a general design question that I'd like to hear some of your opinions on. I am designing a system for a client, and I'm using GridView' a lot. They need a lot of columns to be displayed in some of these, and I've had to resort to using a panel with a horizontal scrollbar. This presents some issues - keeping track of which row is which is difficult, even with alternating row colours, and it's generally pretty ugly. How have you dealt with these issues before? Are there any sort of AJAX controls that could help, so some data could be only displayed on hover or such? Or any other general ideas.

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• When we know a class become too much ?

  - by justjoe

  I start to learn class in PHP. According to my experience with other language, i can tell class is different then function. So, how we spot if our class start to be too much and too important and how we minimize its impact ?

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• Drupal and Back-End Complexity

  - by Brian

  Currently I am working on a school website, and we are still in the decision-making process of choosing a framework (we know that we're not using Joomla! or hand-coding). Drupal came up as a viable choice, and currently, that is my best bet for the site. However, I have an issue with CMS's in general. I would like to develop a quite complicated and specifically custom-suited back-end application for teachers to interact with individual students, including the design of shared/custom calendars, announcement privileges, etc. I currently have a bit of expertise with HTML, CSS, PHP, MySQL, and I could wrap my head around some JavaScript and AJAX stuff if need-be. However, would such a complicated application work with Drupal (in that I could create it to specifically suite my purposes)?

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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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• Looking for a jquery plugin to serialize a form to an object

  - by John

  I'm looking for a jQuery function or plugin that serializes form inputs to an object using the naming convention for deep-serialization supported by param() in jQuery 1.4: <form> <input name="a[b]" value="1"/> <input name="a[c]" value="2"/> <input name="d[]" value="3"/> <input name="d[]" value="4"/> <input name="d[2][e]" value="5"/> </form> $('form').serializeObject(); // { a: { b:1,c:2 }, d: [3,4,{ e:5 }] } Prototype's Form.serialize method can do exactly this. What's the jQuery equivalent? I found this plugin but it doesn't follow this naming convention.

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• Objects with the same set of attributes and methods belongs to the same class?

  - by TiuTalk

  Objects with the same set of attributes and methods belongs to the same class? Can't I declare two identical classes with the same methods and attributes, instanciate them and have "objects with the same set of attributes and methods that belongs to different class"? This question is not about good practices... It's about the logical value (true or false) of the question on the title.

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• syntax problem crating a method that returns an object (java)

  - by David

  I'm trying to create a method that will sum two timeO objects and return a new TimeO object called sum. Here is the relevant code snippet: public static TimeO add (TimeO t1, TimeO t2) { TimeO sum = new TimeO ; ... } When i try to compile it i get this error message: TimeO.java:15: '(' or '[' expected TimeO sum = new TimeO ; ^ 1 error i cant think of any reason why it would want me to open a set of parenthasies or brackets here but its possible that i dont' quite understand the syntax. Whats going wrong here?

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• Refactoring FAT client legacy application

  - by Paul

  I am working on a fat client legacy C++ application which has a lot of business logic mixed in with the presentation side of things. I want to clean things out and refactor the code out completely, so there is a clear seperation of concerns. I am looking at MVC or some other suitable design pattern in order to achieve this. I would like to get recommendations from people who have walked this road before - Do I use MVP or MVC (or another pattern)? What is/are the best practices for undertaking something like this (i.e. useful steps/checks) ?

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