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• GridView edit problem If primary key is editable (design problem)

  - by Nassign

  I would like to ask about the design of table based on it's editability in a Grid View. Let me explain. For example, I have a table named ProductCustomerRel. Method 1 CustomerCode varchar PK ProductCode varchar PK StoreCode varchar PK Quantity int Note text So the combination of the CustomerCode, StoreCode and ProductCode must be unique. The record is displayed on a gridview. The requirement is that you can edit the customer, product and storecode but when the data is saved, the PK constraint must still persist. The problem here is it would be natural for a grid to be able to edit the 3 primary key, you can only achieve the update operation of the grid view by first deleting the row and then inserting the row with the updated data. An alternative to this is to just update the table and add a SeqNo, and just enforce the unique constraint of the 3 columns when inserting and updating in the grid view. Method 2 SeqNo int PK CustomerCode varchar ProductCode varchar StoreCode varchar Quantity int Note text My question is which of the two method is better? or is there another way to do this?

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• Design Pattern for Changing Object

  - by user210757

  Is there a Design Pattern for supporting different permutations object? Version 1 public class myOjbect { public string field1 { get; set; } /* requirements: max length 20 */ public int field2 { get; set; } . . . public decimal field200 { get; set; } } Version 2 public class myObject { public string field1 { get; set; } /* requirements: max length 40 */ public int field2 { get; set; } . . . public double field200 { get; set; } /* changed data types */ . . ./* 10 new properties */ public double field210 { get; set; } } of course I could just have separate objects, but thought there might be a good pattern for this sort of thing.

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• Design Advice Needed For Synonyms Database

  - by James J

  I'm planning to put together a database that can be used to query synonyms of words. The database will end up huge, so the idea is to keep things running fast. I've been thinking about how to do this, but my database design skills are not up to scratch these days. My initial idea was to have each word stored in one table, and then another table with a 1 to many relationship where each word can be linked to another word and that table can be queried. The application I'm developing allows users to highlight a word, and then type in, or select some synonyms from the database for that word. The application learns from the user input so if someone highlights "car" and types in "motor" the database would be updated to link the relationship if it don't exist already. What I don't want to happen is for a user to type in the word "shop" and link it to the word car. So I'm thinking I will need to add some sort of weight to each relationship. Eventually the synonyms the users enter will be used so they can auto select common synonyms used with a certain word. The lower weight words will not be displayed so shop could never be a synonym of car unless it had a very high weight, and chances are nobody is going to do that. Does the above sound right? Can you offer any suggestions or improvements?

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• Controlling a GameObject from another GameObject's script component

  - by OhMrBigshot

  I'm creating a game where when starting the game, a Cube is duplicated GridSize * GridSize times when the game starts. Now, after the cubes are duplicated I want to attach a variable to them, say "Flag" which is a bool, from another script component (let's say I have a Prefab that generates the cloned cubes). In short, I have something like this: CreateTiles.cs : Attached to Prefab void Start() { createMyTiles(); // a function that clones the tiles flagRandomTiles(); // a function that (what I'm trying to do) "Flags" 10 random cubes } CubeBehavior.cs : Attached to each Cube public bool hasFlag; // other stuff Now, I want flagRandomTiles() to set a Cube's hasFlag property via code, assuming I have access to them via a GameObject[] array. Here's what I've tried: Cubes[x].hasFlag = true; - No access. Making a function such as Cubes[x].setHasFlag(true) - still no access. Initializing Cubes as a CubeBehavior object array, then doing the above - GameObjects can't be converted to CubeBehaviors - I get this error when I try to assign the Cubes into the array. How do I do this?

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• Multilingual website without language component in the URL

  - by user359650

  I'm working on a website for Canada which will have French and English versions. For SEO purposes, I would like to avoid using any language tag in URLs because I believe it will have more impact (e.g. example.ca/products better than en.example.ca/products or example.ca/en/products). I believe this is technically possible because the2 languages are sufficiently different that the URLs won't be conflicting with one another (e.g. if you want a "product" page, it will be /products in English, and /produits in French so you know which language the URL is about). Since Google (and most likely others) doesn't rely on the URL (nor HTML tags) to determine the content language I don't see any problems with search engines. To make this possible I've thought about using a cookie distinct from the session cookie (e.g. example.org_language) with long term expiry (e.g. N years) that will memorize the language chosen by the user. That way when people visit the website with a new browser session, they get served the proper language. I have already given up on users being able to switch one page from English to French: when people will chose English or French from the menu they will be redirected to the corresponding version of the home page. Do you foresee any problems with not using a language component in the URL (whether domain or path)? (as long as one makes sure URLS don't conflict).

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• Objective-C wrapper API design methodology

  - by Wade Williams

  I know there's no one answer to this question, but I'd like to get people's thoughts on how they would approach the situation. I'm writing an Objective-C wrapper to a C library. My goals are: 1) The wrapper use Objective-C objects. For example, if the C API defines a parameter such as char *name, the Objective-C API should use name:(NSString *). 2) The client using the Objective-C wrapper should not have to have knowledge of the inner-workings of the C library. Speed is not really any issue. That's all easy with simple parameters. It's certainly no problem to take in an NSString and convert it to a C string to pass it to the C library. My indecision comes in when complex structures are involved. Let's say you have: struct flow { long direction; long speed; long disruption; long start; long stop; } flow_t; And then your C API call is: void setFlows(flow_t inFlows[4]); So, some of the choices are: 1) expose the flow_t structure to the client and have the Objective-C API take an array of those structures 2) build an NSArray of four NSDictionaries containing the properties and pass that as a parameter 3) create an NSArray of four "Flow" objects containing the structure's properties and pass that as a parameter My analysis of the approaches: Approach 1: Easiest. However, it doesn't meet the design goals Approach 2: For some reason, this seems to me to be the most "Objective-C" way of doing it. However, each element of the NSDictionary would have to be wrapped in an NSNumber. Now it seems like we're doing an awful lot just to pass the equivalent of a struct. Approach 3: Seems the cleanest to me from an object-oriented standpoint and the extra encapsulation could come in handy later. However, like #2, it now seems like we're doing an awful lot (creating an array, creating and initializing objects) just to pass a struct. So, the question is, how would you approach this situation? Are there other choices I'm not considering? Are there additional advantages or disadvantages to the approaches I've presented that I'm not considering?

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• Design question for WinForms (C#) app, using Entity Framework

  - by cdotlister

  I am planning on writing a small home budget application for myself, as a learning excercise. I have built my database (SQL Server), and written a small console application to interact with it, and test out scenarios on my database. Once I am happy, my next step would be to start building the application - but I am already wondering what the best/standard design would be. I am palnning on using Entity Framework for handling my database entities... then linq to sql/objects for getting the data, all running under a WinForms (for now) application. My plan (I've never used EF... and most of my development background is Web apps) is to have my database... with Entity Framework in it's own project.. which has the connection to the database. This project would expose methods such as 'GetAccount()', 'GetAccount(int accountId)' etc. I'd then have a service project that references my EF project. And on top of that, my GUI project, which makes the calls to my service project. But I am stuck. Lets say I have a screen that displays a list of Account types (Debit, Credit, Loan...). Once I have selected one, the next drop down shows a list of accounts I have that suite that account type. So, my OnChange event on my DropDown on the account type control will make a call to the serviceLayer project, 'GetAccountTypes()', and I would expect back a List< of Account Types. However, the AccountType object ... what is that? That can't be the AccountType object from my EF project, as my GUI project doesn't have reference to it. Would I have to have some sort of Shared Library, shared between my GUI and my Service project, with a custom built AccountType object? The GUI can then expect back a list of these. So my service layer would have a method: public List<AccountType> GetAccountTypes() That would then make a call to a custom method in my EF project, which would probably be the same as the above method, except, it returns an list of EF.Data.AccountType (The Entity Framework generated Account Type object). The method would then have the linq code to get the data as I want it. Then my service layer will get that object, and transform it unto my custom AccountType object, and return it to the GUI. Does that sound at all like a good plan?

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• C# Design Questions

  - by guazz

  How to approach unit testing of private methods? I have a class that loads Employee data into a database. Here is a sample: public class EmployeeFacade { public Employees EmployeeRepository = new Employees(); public TaxDatas TaxRepository = new TaxDatas(); public Accounts AccountRepository = new Accounts(); //and so on for about 20 more repositories etc. public bool LoadAllEmployeeData(Employee employee) { if (employee == null) throw new Exception("..."); EmployeeRepository emps = new EmployeeRepository(); bool exists = emps.FetchExisting(emps.Id); if (!exists) { emps.AddNew(); } try { emps.Id = employee.Id; emps.Name = employee.EmployeeDetails.PersonalDetails.Active.Names.FirstName; emps.SomeOtherAttribute; } catch() {} try { emps.Save(); } catch(){} try { LoadorUpdateTaxData(employee.TaxData); } catch() {} try { LoadorUpdateAccountData(employee.AccountData); } catch() {} ... etc. for about 20 more other employee objects } private bool LoadorUpdateTaxData(employeeId, TaxData taxData) { if (taxData == null) throw new Exception("..."); ...same format as above but using AccountRepository } private bool LoadorUpdateAccountData(employee.TaxData) { ...same format as above but using TaxRepository } } I am writing an application to take serialised objects(e.g. Employee above) and load the data to the database. I have a few design question that I would like opinions on: A - I am calling this class "EmployeeFacade" because I am (attempting?) to use the facade pattern. Is it good practace to name the pattern on the class name? B - Is it good to call the concrete entities of my DAL layer classes "Repositories" e.g. "EmployeeRepository" ? C - Is using the repositories in this way sensible or should I create a method on the repository itself to take, say, the Employee and then load the data from there e.g. EmployeeRepository.LoadAllEmployeeData(Employee employee)? I am aim for cohesive class and but this will requrie the repository to have knowledge of the Employee object which may not be good? D - Is there any nice way around of not having to check if an object is null at the begining of each method? E - I have a EmployeeRepository, TaxRepository, AccountRepository declared as public for unit testing purpose. These are really private enities but I need to be able to substitute these with stubs so that the won't write to my database(I overload the save() method to do nothing). Is there anyway around this or do I have to expose them? F - How can I test the private methods - or is this done (something tells me it's not)? G- "emps.Name = employee.EmployeeDetails.PersonalDetails.Active.Names.FirstName;" this breaks the Law of Demeter but how do I adjust my objects to abide by the law?

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• Design pattern question: encapsulation or inheritance

  - by Matt

  Hey all, I have a question I have been toiling over for quite a while. I am building a templating engine with two main classes Template.php and Tag.php, with a bunch of extension classes like Img.php and String.php. The program works like this: A Template object creates a Tag objects. Each tag object determines which extension class (img, string, etc.) to implement. The point of the Tag class is to provide helper functions for each extension class such as wrap('div'), addClass('slideshow'), etc. Each Img or String class is used to render code specific to what is required, so $Img->render() would give something like <img src='blah.jpg' /> My Question is: Should I encapsulate all extension functionality within the Tag object like so: Tag.php function __construct($namespace, $args) { // Sort out namespace to determine which extension to call $this->extension = new $namespace($this); // Pass in Tag object so it can be used within extension return $this; // Tag object } function render() { return $this->extension->render(); } Img.php function __construct(Tag $T) { $args = $T->getArgs(); $T->addClass('img'); } function render() { return '<img src="blah.jpg" />'; } Usage: $T = new Tag("img", array(...); $T->render(); .... or should I create more of an inheritance structure because "Img is a Tag" Tag.php public static create($namespace, $args) { // Sort out namespace to determine which extension to call return new $namespace($args); } Img.php class Img extends Tag { function __construct($args) { // Determine namespace then call create tag $T = parent::__construct($namespace, $args); } function render() { return '<img src="blah.jpg" />'; } } Usage: $Img = Tag::create('img', array(...)); $Img->render(); One thing I do need is a common interface for creating custom tags, ie I can instantiate Img(...) then instantiate String(...), I do need to instantiate each extension using Tag. I know this is somewhat vague of a question, I'm hoping some of you have dealt with this in the past and can foresee certain issues with choosing each design pattern. If you have any other suggestions I would love to hear them. Thanks! Matt Mueller

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• JavaScript Resource Management Design Pattern

  - by Adam

  As a web developer, a common problem I find myself tackling is waiting for something to load before doing something else. In particular, I often hide (using either display: none; or visibility: hidden; depending on the situation) elements while waiting for a background image or a CSS file to load. Consider this example from Last.FM. They overlay a semi-transparant PNG over each album art image so that it looks like it's inside a jewel-case. They let it load when it loads, so depending on your internet speed, you may see the art image by itself (without the overlay) temporarily. In this case, the album art looks fine without the jewel-case effect. But in similar situations, I have found that I don't want the user to see the site's design mangled as resources incrementally load. So, in rare cases I have hidden everything from the user until the whole kit and kaboodle has loaded. But this is often a pain to write out, and may force the user to wait for a pretty long time to see anything (besides "loading..." text). I can think of (and have used on occasion) some obvious solutions/compromises: Use some inline CSS so that as certain parts of the DOM load and render, they will immediately have the correct size/position/etc. Immediately render the navigation part of the site, so that if the user wanted to use the current page purely to get somewhere else, they don't have to wait for the rest to load. Load pixelated images first as placeholders for layout while lazy-loading higher quality images as replacements. Something quirky like using a cute animated gif to distract the user during a "loading..." phase. Show useful information as a reference while loading the full UI. (Something akin to Gmail Inbox Preview, etc.) (Sorry if my question was basically just asked and answered...) Despite all of these ideas, I still find myself hoping there are better ways of doing some of these things. So I guess what I'm looking for is some inspiration and/or any creative ways of dealing with this problem that you guys may have seen out in the wild.

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• SQLAlchemy unsupported type error - and table design issues?

  - by Az

  Hi there, back again with some more SQLAlchemy shenanigans. Let me step through this. My table is now set up as so: engine = create_engine('sqlite:///:memory:', echo=False) metadata = MetaData() students_table = Table('studs', metadata, Column('sid', Integer, primary_key=True), Column('name', String), Column('preferences', Integer), Column('allocated_rank', Integer), Column('allocated_project', Integer) ) metadata.create_all(engine) mapper(Student, students_table) Fairly simple, and for the most part I've been enjoying the ability to query almost any bit of information I want provided I avoid the error cases below. The class it is mapped from is: class Student(object): def __init__(self, sid, name): self.sid = sid self.name = name self.preferences = collections.defaultdict(set) self.allocated_project = None self.allocated_rank = 0 def __repr__(self): return str(self) def __str__(self): return "%s %s" %(self.sid, self.name) Explanation: preferences is basically a set of all the projects the student would prefer to be assigned. When the allocation algorithm kicks in, a student's allocated_project emerges from this preference set. Now if I try to do this: for student in students.itervalues(): session.add(student) session.commit() It throws two errors, one for the allocated_project column (seen below) and a similar error for the preferences column: sqlalchemy.exc.InterfaceError: (InterfaceError) Error binding parameter 4 - probably unsupported type. u'INSERT INTO studs (sid, name, allocated_rank, allocated_project) VALUES (?, ?, ?, ?, ?, ?, ?)' [1101, 'Muffett,M.', 1, 888 Human-spider relationships (Supervisor id: 123)] If I go back into my code I find that, when I'm copying the preferences from the given text files, it actually refers to the Project class which is mapped to a dictionary, using the unique project id's (pid) as keys. Thus, as I iterate through each student via their rank and to the preferences set, it adds not a project id, but the reference to the project id from the projects dictionary. students[sid].preferences[int(rank)].add(projects[int(pid)]) Now this is very useful to me since I can find out all I want to about a student's preferred projects without having to run another check to pull up information about the project id. The form you see in the error has the object print information passed as: return "%s %s (Supervisor id: %s)" %(self.proj_id, self.proj_name, self.proj_sup) My questions are: I'm trying to store an object in a database field aren't I? Would the correct way then, be copying the project information (project id, name, etc) into its own table, referenced by the unique project id? That way I can just have the project id field for one of the student tables just be an integer id and when I need more information, just join the tables? So and so forth for other tables? If the above makes sense, then how does one maintain the relationship with a column of information in one table which is a key index on another table? Does this boil down into a database design problem? Are there any other elegant ways of accomplishing this? Apologies if this is a very long-winded question. It's rather crucial for me to solve this, so I've tried to explain as much as I can, whilst attempting to show that I'm trying (key word here sadly) to understand what could be going wrong.

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• Detect if Java Swing component has been hidden

  - by kayahr

  Assume we have the following Swing application: final JFrame frame = new JFrame(); final JPanel outer = new JPanel(); frame.add(outer); JComponent inner = new SomeSpecialComponent(); outer.add(inner); So in this example we simply have an outer panel in the frame and a special component in the panel. This special component must do something when it is hidden and shown. But the problem is that setVisible() is called on the outer panel and not on the special component. So I can't override the setVisible method in the special component and I also can't use a component listener on it. I could register the listener on the parent component but what if the outer panel is also in another panel and this outer outer panel is hidden? Is there an easier solution than recursively adding componentlisteners to all parent components to detect a visibility change in SomeSpecialComponent?

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• Render ViewComponent from another component codebehind

  - by George Polevoy

  I'm trying to render a component from withing another component. public override void Render() // ... var block = new Block(); block.Init(EngineContext, Context); block.Render(); // ... } The problem is that Block component can't find it's template. ResourceProcessingException Message: Unable to process resource 'components\CustomReportComponentComponent\default.vm': Resource could not be located I guess, other problems can arise because the component is not properly initialized. Is it possible to initialize a component from within another component's Render method, so it renders just as if called from a .vm?

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• What is good practice in .NET system architecture design concerning multiple models and aggregates

  - by BuzzBubba

  I'm designing a larger enterprise architecture and I'm in a doubt about how to separate the models and design those. There are several points I'd like suggestions for: - models to define - way to define models Currently my idea is to define: Core (domain) model Repositories to get data to that domain model from a database or other store Business logic model that would contain business logic, validation logic and more specific versions of forms of data retrieval methods View models prepared for specifically formated data output that would be parsed by views of different kind (web, silverlight, etc). For the first model I'm puzzled at what to use and how to define the mode. Should this model entities contain collections and in what form? IList, IEnumerable or IQueryable collections? - I'm thinking of immutable collections which IEnumerable is, but I'd like to avoid huge data collections and to offer my Business logic layer access with LINQ expressions so that query trees get executed at Data level and retrieve only really required data for situations like the one when I'm retrieving a very specific subset of elements amongst thousands or hundreds of thousands. What if I have an item with several thousands of bids? I can't just make an IEnumerable collection of those on the model and then retrieve an item list in some Repository method or even Business model method. Should it be IQueryable so that I actually pass my queries to Repository all the way from the Business logic model layer? Should I just avoid collections in my domain model? Should I void only some collections? Should I separate Domain model and BusinessLogic model or integrate those? Data would be dealt trough repositories which would use Domain model classes. Should repositories be used directly using only classes from domain model like data containers? This is an example of what I had in mind: So, my Domain objects would look like (e.g.) public class Item { public string ItemName { get; set; } public int Price { get; set; } public bool Available { get; set; } private IList<Bid> _bids; public IQueryable<Bid> Bids { get { return _bids.AsQueryable(); } private set { _bids = value; } } public AddNewBid(Bid newBid) { _bids.Add(new Bid {.... } } Where Bid would be defined as a normal class. Repositories would be defined as data retrieval factories and used to get data into another (Business logic) model which would again be used to get data to ViewModels which would then be rendered by different consumers. I would define IQueryable interfaces for all aggregating collections to get flexibility and minimize data retrieved from real data store. Or should I make Domain Model "anemic" with pure data store entities and all collections define for business logic model? One of the most important questions is, where to have IQueryable typed collections? - All the way from Repositories to Business model or not at all and expose only solid IList and IEnumerable from Repositories and deal with more specific queries inside Business model, but have more finer grained methods for data retrieval within Repositories. So, what do you think? Have any suggestions?

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• Executing Stored Procedure for each InputRow + SSIS Script Component.

  - by Nev_Rahd

  Hello, In my Script Component, am trying to execute Stored Procedure = which return multiple rows = of which need to generate output rows. Code as below: /* Microsoft SQL Server Integration Services Script Component * Write scripts using Microsoft Visual C# 2008. * ScriptMain is the entry point class of the script.*/ using System; using System.Data; using System.Data.SqlClient; using Microsoft.SqlServer.Dts.Pipeline.Wrapper; using Microsoft.SqlServer.Dts.Runtime.Wrapper; [Microsoft.SqlServer.Dts.Pipeline.SSISScriptComponentEntryPointAttribute] public class ScriptMain : UserComponent { SqlConnection cnn = new SqlConnection(); IDTSConnectionManager100 cnManager; //string cmd; SqlCommand cmd = new SqlCommand(); public override void AcquireConnections(object Transaction) { cnManager = base.Connections.myConnection; cnn = (SqlConnection)cnManager.AcquireConnection(null); } public override void PreExecute() { base.PreExecute(); } public override void PostExecute() { base.PostExecute(); } public override void InputRows_ProcessInputRow(InputRowsBuffer Row) { while(Row.NextRow()) { DataTable dt = new DataTable(); cmd.Connection = cnn; cmd.CommandText = "OSPATTRIBUTE_GetOPNforOP"; cmd.CommandType = CommandType.StoredProcedure; cmd.Parameters.Add("@NK", SqlDbType.VarChar).Value = Row.OPNK.ToString(); cmd.Parameters.Add("@EDWSTARTDATE", SqlDbType.DateTime).Value = Row.EDWEFFECTIVESTARTDATETIME; SqlDataAdapter adapter = new SqlDataAdapter(cmd); adapter.Fill(dt); foreach (DataRow dtrow in dt.Rows) { OutputValidBuffer.AddRow(); OutputValidBuffer.OPNK = Row.OPNK; OutputValidBuffer.OSPTYPECODE = Row.OSPTYPECODE; OutputValidBuffer.ORGPROVTYPEDESC = Row.ORGPROVTYPEDESC; OutputValidBuffer.HEALTHSECTORCODE = Row.HEALTHSECTORCODE; OutputValidBuffer.HEALTHSECTORDESCRIPTION = Row.HEALTHSECTORDESCRIPTION; OutputValidBuffer.EDWEFFECTIVESTARTDATETIME = Row.EDWEFFECTIVESTARTDATETIME; OutputValidBuffer.EDWEFFECTIVEENDDATETIME = Row.EDWEFFECTIVEENDDATETIME; OutputValidBuffer.OPQI = Row.OPQI; OutputValidBuffer.OPNNK = dtrow[0].ToString(); OutputValidBuffer.OSPNAMETYPECODE = dtrow[1].ToString(); OutputValidBuffer.NAMETYPEDESC = dtrow[2].ToString(); OutputValidBuffer.OSPNAME = dtrow[3].ToString(); OutputValidBuffer.EDWEFFECTIVESTARTDATETIME1 = Row.EDWEFFECTIVESTARTDATETIME; OutputValidBuffer.EDWEFFECTIVEENDDATETIME1 = Row.EDWEFFECTIVEENDDATETIME; OutputValidBuffer.OPNQI = dtrow[6].ToString(); } } } public override void ReleaseConnections() { cnManager.ReleaseConnection(cnn); } } This is always skipping the first row. while(Row.NextRow()) is always bringing the second row of the input buffer. What am I doing wrong. Thanks

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• Looking for a better design: A readonly in-memory cache mechanism

  - by Dylan Lin

  Hi all, I have a Category entity (class), which has zero or one parent Category and many child Categories -- it's a tree structure. The Category data is stored in a RDBMS, so for better performance, I want to load all categories and cache them in memory while launching the applicaiton. Our system can have plugins, and we allow the plugin authors to access the Category Tree, but they should not modify the cached items and the tree(I think a non-readonly design might cause some subtle bugs in this senario), only the system knows when and how to refresh the tree. Here are some demo codes: public interface ITreeNode<T> where T : ITreeNode<T> { // No setter T Parent { get; } IEnumerable<T> ChildNodes { get; } } // This class is generated by O/R Mapping tool (e.g. Entity Framework) public class Category : EntityObject { public string Name { get; set; } } // Because Category is not stateless, so I create a cleaner view class for Category. // And this class is the Node Type of the Category Tree public class CategoryView : ITreeNode<CategoryView> { public string Name { get; private set; } #region ITreeNode Memebers public CategoryView Parent { get; private set; } private List<CategoryView> _childNodes; public IEnumerable<CategoryView> ChildNodes { return _childNodes; } #endregion public static CategoryView CreateFrom(Category category) { // here I can set the CategoryView.Name property } } So far so good. However, I want to make ITreeNode interface reuseable, and for some other types, the tree should not be readonly. We are not able to do this with the above readonly ITreeNode, so I want the ITreeNode to be like this: public interface ITreeNode<T> { // has setter T Parent { get; set; } // use ICollection<T> instead of IEnumerable<T> ICollection<T> ChildNodes { get; } } But if we make the ITreeNode writable, then we cannot make the Category Tree readonly, it's not good. So I think if we can do like this: public interface ITreeNode<T> { T Parent { get; } IEnumerable<T> ChildNodes { get; } } public interface IWritableTreeNode<T> : ITreeNode<T> { new T Parent { get; set; } new ICollection<T> ChildNodes { get; } } Is this good or bad? Are there some better designs? Thanks a lot! :)

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• How to Add Smart Tags to my .net component?

  - by Wael Dalloul

  look at the following picture, which showing smart tag for DataGridView Now I'm creating new component and I want it to support showing some properties in Smart Tags, how to add the properties to the smart Tag?

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• Can i add a component in jframe in netbeans at runtime?

  - by chintan

  I am having a form built up in netbeans and want to add or remove a component with an actionperformed event of a button or a combobox is it possible? if yes, how?

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• How can I specify the Owner of component read from a Delphi TStream?

  - by Roddy

  I'm reading a component from a stream, and want to be able to specify the Owner property. var TComponent : comp; stream.Seek(0, soFromBeginning); comp := stream.ReadComponent(nil); Who owns comp, and how can I change it? I'd hoped the parameter to readComponent would be the owner, but it seems to do something totally different!

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• Signals and threads - good or bad design decision?

  - by Jens

  I have to write a program that performs highly computationally intensive calculations. The program might run for several days. The calculation can be separated easily in different threads without the need of shared data. I want a GUI or a web service that informs me of the current status. My current design uses BOOST::signals2 and BOOST::thread. It compiles and so far works as expected. If a thread finished one iteration and new data is available it calls a signal which is connected to a slot in the GUI class. My question(s): Is this combination of signals and threads a wise idea? I another forum somebody advised someone else not to "go down this road". Are there potential deadly pitfalls nearby that I failed to see? Is my expectation realistic that it will be "easy" to use my GUI class to provide a web interface or a QT, a VTK or a whatever window? Is there a more clever alternative (like other boost libs) that I overlooked? following code compiles with g++ -Wall -o main -lboost_thread-mt <filename>.cpp code follows: #include <boost/signals2.hpp> #include <boost/thread.hpp> #include <boost/bind.hpp> #include <iostream> #include <iterator> #include <string> using std::cout; using std::cerr; using std::string; /** * Called when a CalcThread finished a new bunch of data. */ boost::signals2::signal<void(string)> signal_new_data; /** * The whole data will be stored here. */ class DataCollector { typedef boost::mutex::scoped_lock scoped_lock; boost::mutex mutex; public: /** * Called by CalcThreads call the to store their data. */ void push(const string &s, const string &caller_name) { scoped_lock lock(mutex); _data.push_back(s); signal_new_data(caller_name); } /** * Output everything collected so far to std::out. */ void out() { typedef std::vector<string>::const_iterator iter; for (iter i = _data.begin(); i != _data.end(); ++i) cout << " " << *i << "\n"; } private: std::vector<string> _data; }; /** * Several of those can calculate stuff. * No data sharing needed. */ struct CalcThread { CalcThread(string name, DataCollector &datcol) : _name(name), _datcol(datcol) { } /** * Expensive algorithms will be implemented here. * @param num_results how many data sets are to be calculated by this thread. */ void operator()(int num_results) { for (int i = 1; i <= num_results; ++i) { std::stringstream s; s << "["; if (i == num_results) s << "LAST "; s << "DATA " << i << " from thread " << _name << "]"; _datcol.push(s.str(), _name); } } private: string _name; DataCollector &_datcol; }; /** * Maybe some VTK or QT or both will be used someday. */ class GuiClass { public: GuiClass(DataCollector &datcol) : _datcol(datcol) { } /** * If the GUI wants to present or at least count the data collected so far. * @param caller_name is the name of the thread whose data is new. */ void slot_data_changed(string caller_name) const { cout << "GuiClass knows: new data from " << caller_name << std::endl; } private: DataCollector & _datcol; }; int main() { DataCollector datcol; GuiClass mc(datcol); signal_new_data.connect(boost::bind(&GuiClass::slot_data_changed, &mc, _1)); CalcThread r1("A", datcol), r2("B", datcol), r3("C", datcol), r4("D", datcol), r5("E", datcol); boost::thread t1(r1, 3); boost::thread t2(r2, 1); boost::thread t3(r3, 2); boost::thread t4(r4, 2); boost::thread t5(r5, 3); t1.join(); t2.join(); t3.join(); t4.join(); t5.join(); datcol.out(); cout << "\nDone" << std::endl; return 0; }

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• File Watcher Task

  The task will detect changes to existing files as well as new files, both actions will cause the file to be found when available. A file is available when the task can open it exclusively. This is important for files that take a long time to be written, such as large files, or those that are just written slowly or delivered via a slow network link. It can also be set to look for existing files first (1.2.4.55). The full path of the found file is returned in up to three ways: The ExecValueVariable of the task. This can be set to any String variable. The OutputVariableName when specified. This can be set to any String variable. The FullPath variable within OnFileFoundEvent. This is a File Watcher Task specific event.   Advanced warning of a file having been detected, but not yet available is returned through the OnFileWatcherEvent. This event does not always coincide with the completion of the task, as completion and the OnFileFoundEvent is delayed until the file is ready for use. This event indicates that a file has been detected, and that file will now be monitored until it becomes available. The task will only detect and report on the first file that is created or changes, any subsequent changes will be ignored. Task properties and there usages are documented below: Property Data Type Description Filter String Default filter *.* will watch all files. Standard windows wildcards and patterns can be used to restrict the files monitored. FindExistingFiles Boolean Indicates whether the task should check for any existing files that match the path and filter criteria, before starting the file watcher. IncludeSubdirectories Boolean Indicates whether changes in subdirectories are accepted or ignored. OutputVariableName String The name of the variable into which the full file path found will be written on completion of the task. The variable specified should be of type string. Path String Path to watch for new files or changes to existing files. The path is a directory, not a full filename. For a specific file, enter the file name in the Filter property and the directory in the Path property. PathInputType FileWatcherTask.InputType Three input types are supported for the path: Connection - File connection manager, of type existing folder. Direct Input - Type the path directly into the UI or set on the property as a literal string. Variable – The name of the variable which contains the path. Timeout Integer Time in minutes to wait for a file. If no files are detected within the timeout period the task will fail. The default value of 0 means infinite, and will not expire. TimeoutAsWarning Boolean The default behaviour is to raise an error and fail the task on timeout. This property allows you to suppress the error on timeout, a warning event is raised instead, and the task succeeds. The default value is false.   Installation The task is provided as an MSI file which you can download and run to install it. This simply places the files on disk in the correct locations and also installs the assemblies in the Global Assembly Cache as per Microsoft’s recommendations. You may need to restart the SQL Server Integration Services service, as this caches information about what components are installed, as well as restarting any open instances of Business Intelligence Development Studio (BIDS) / Visual Studio that you may be using to build your SSIS packages. For 2005/2008 Only - Finally you will have to add the task to the Visual Studio toolbox manually. Right-click the toolbox, and select Choose Items.... Select the SSIS Control Flow Items tab, and then check the File Watcher Task in the Choose Toolbox Items window. This process has been described in detail in the related FAQ entry for How do I install a task or transform component? We recommend you follow best practice and apply the current Microsoft SQL Server Service pack to your SQL Server servers and workstations. Downloads The File Watcher Task  is available for SQL Server 2005, SQL Server 2008 (includes R2) and SQL Server 2012. Please choose the version to match your SQL Server version, or you can install multiple versions and use them side by side if you have more than one version of SQL Server installed. File Watcher Task for SQL Server 2005 File Watcher Task for SQL Server 2008 File Watcher Task for SQL Server 2012 Version History SQL Server 2012 Version 3.0.0.16 - SQL Server 2012 release. Includes upgrade support for both 2005 and 2008 packages to 2012. (5 Jun 2012) SQL Server 2008 Version 2.0.0.14 - Fixed user interface bug. A migration problem caused the UI type editors to reference an old SQL 2005 assembly. (17 Nov 2008) Version 2.0.0.7 - SQL Server 2008 release. (20 Oct 2008) SQL Server 2005 Version 1.2.6.100 - Fixed UI bug with TimeoutAsWarning property not saving correctly. Improved expression support in UI. File availability detection changed to use read-only lock, allowing reduced permissions to be used. Corrected installed issue which prevented installation on 64-bit machines with SSIS runtime only components. (18 Mar 2007) Version 1.2.5.73 - Added TimeoutAsWarning property. Gives the ability to suppress the error on timeout, a warning event is raised instead, and the task succeeds. (Task Version 3) (27 Sep 2006) Version 1.2.4.61 - Fixed a bug which could cause a loop condition with an unexpected exception such as incorrect file permissions. (20 Sep 2006) Version 1.2.4.55 - Added FindExistingFiles property. When true the task will check for an existing file before the file watcher itself actually starts. (Task Version 2) (8 Sep 2006) Version 1.2.3.39 - SQL Server 2005 RTM Refresh. SP1 Compatibility Testing. Property type validation improved. (12 Jun 2006) Version 1.2.1.0 - SQL Server 2005 IDW 16 Sept CTP. Futher UI enhancements, including expression indicator. Fixed bug caused by execution within loop Subsequent iterations detected the same file as the first iteration. Added IncludeSubdirectories property. Fixed bug when changes made in subdirectories, and folder change was detected, causing task failure. (Task Version 1) (6 Oct 2005) Version 1.2.0.0 - SQL Server 2005 IDW 15 June CTP. Changes made include an enhanced UI, the PathInputType property for greater flexibility with path input, the OutputVariableName property, and the new OnFileFoundEvent event. (7 Sep 2005) Version 1.1.2 - Public Release (16 Nov 2004) Screenshots   Troubleshooting Make sure you have downloaded the version that matches your version of SQL Server. We offer separate downloads for SQL Server 2005 and SQL Server 2008. If you an error when you try and use the task along the lines of The task with the name "File Watcher Task" and the creation name ... is not registered for use on this computer, this usually indicates that the internal cache of SSIS components needs to be updated. This cache is held by the SSIS service, so you need restart the the SQL Server Integration Services service. You can do this from the Services applet in Control Panel or Administrative Tools in Windows. You can also restart the computer if you prefer. You may also need to restart any current instances of Business Intelligence Development Studio (BIDS) / Visual Studio that you may be using to build your SSIS packages. The full error message is shown below for reference: TITLE: Microsoft Visual Studio ------------------------------ The task with the name "File Watcher Task" and the creation name "Konesans.Dts.Tasks.FileWatcherTask.FileWatcherTask, Konesans.Dts.Tasks.FileWatcherTask, Version=1.2.0.0, Culture=neutral, PublicKeyToken=b2ab4a111192992b" is not registered for use on this computer. Contact Information: File Watcher Task A similar error message can be shown when trying to edit the task if the Microsoft Exception Message Box is not installed. This useful component is installed as part of the SQL Server Management Studio tools but occasionally due to the custom options chosen during SQL Server 2005 setup it may be absent. If you get an error like Could not load file or assembly 'Microsoft.ExceptionMessageBox.. you can manually download and install the missing component. It is available as part of the Feature Pack for SQL Server 2005 release. The feature packs are occasionally updated by Microsoft so you may like to check for a more recent edition, but you can find the Microsoft Exception Message Box download links here - Feature Pack for Microsoft SQL Server 2005 - April 2006 If you encounter this problem on SQL Server 2008, please check that you have installed the SQL Server client components. The component is no longer available as a separate download for SQL Server 2008  as noted in the Microsoft documentation for Deploying an Exception Message Box Application The full error message is shown below for reference, although note that the Version will change between SQL Server 2005 and SQL Server 2008: TITLE: Microsoft Visual Studio ------------------------------ Cannot show the editor for this task. ------------------------------ ADDITIONAL INFORMATION: Could not load file or assembly 'Microsoft.ExceptionMessageBox, Version=9.0.242.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91' or one of its dependencies. The system cannot find the file specified. (Konesans.Dts.Tasks.FileWatcherTask) Once installation is complete you need to manually add the task to the toolbox before you will see it and to be able add it to packages - How do I install a task or transform component? If you are still having issues then contact us, but please provide as much detail as possible about error, as well as which version of the the task you are using and details of the SSIS tools installed. Sample Code If you wanted to use the task programmatically then here is some sample code for creating a basic package and configuring the task. It uses a variable to supply the path to watch, and also sets a variable for the OutputVariableName. Once execution is complete it writes out the file found to the console. /// <summary> /// Create a package with an File Watcher Task /// </summary> public void FileWatcherTaskBasic() { // Create the package Package package = new Package(); package.Name = "FileWatcherTaskBasic"; // Add variable for input path, the folder to look in package.Variables.Add("InputPath", false, "User", @"C:\Temp\"); // Add variable for the file found, to be used on OutputVariableName property package.Variables.Add("FileFound", false, "User", "EMPTY"); // Add the Task package.Executables.Add("Konesans.Dts.Tasks.FileWatcherTask.FileWatcherTask, " + "Konesans.Dts.Tasks.FileWatcherTask, Version=1.2.0.0, Culture=neutral, PublicKeyToken=b2ab4a111192992b"); // Get the task host wrapper TaskHost taskHost = package.Executables[0] as TaskHost; // Set basic properties taskHost.Properties["PathInputType"].SetValue(taskHost, 1); // InputType.Variable taskHost.Properties["Path"].SetValue(taskHost, "User::InputPath"); taskHost.Properties["OutputVariableName"].SetValue(taskHost, "User::FileFound"); #if DEBUG // Save package to disk, DEBUG only new Application().SaveToXml(String.Format(@"C:\Temp\{0}.dtsx", package.Name), package, null); #endif // Display variable value before execution to check EMPTY Console.WriteLine("Result Variable: {0}", package.Variables["User::FileFound"].Value); // Execute package package.Execute(); // Display variable value after execution, e.g. C:\Temp\File.txt Console.WriteLine("Result Variable: {0}", package.Variables["User::FileFound"].Value); // Perform simple check for execution errors if (package.Errors.Count > 0) foreach (DtsError error in package.Errors) { Console.WriteLine("ErrorCode : {0}", error.ErrorCode); Console.WriteLine(" SubComponent : {0}", error.SubComponent); Console.WriteLine(" Description : {0}", error.Description); } else Console.WriteLine("Success - {0}", package.Name); // Clean-up package.Dispose(); } (Updated installation and troubleshooting sections, and added sample code July 2009)

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• Is there a way to put relationships/contraints into CSS?

  - by hekevintran

  In every design tool or art principle I've heard of, relationships are a central theme. By relationships I mean the thing you can do in Adobe Illustrator to specify that the height of one shape is equal to half the height of another. You cannot express this information in CSS. CSS hard-codes all values. Using a language like LESS that allows variables and arithmetic you can get closer to relationships but it's still a CSS variant. This inability in my mind is the biggest problem with CSS. CSS is supposed to be a language that describes the visual component of a Web page but it ignores relationships and contraints, ideas that are at the core of art. How possible is it to imagine a new Web design language that can express relationships and contraints that can be implemented in JavaScript using the current CSS properties?

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• how to avoid returning mocks from a mocked object list

  - by koen

  I'm trying out mock/responsibility driven design. I seem to have problems to avoid returning mocks from mocks in the case of finder objects. An example could be an object that checks whether the bills from last month are paid. It needs a service that retrieves a list of bills for that. So I need to mock that service that retrieves the bills. At the same time I need that mock to return mocked Bills (since I don't want my test to rely on the correctness bill implementation). Is my design flawed? Is there a better way to test this? Or is this the way it will need to be when using finder objects (the finding of the bills in this case)?

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• Plan variable and call dependencies

  - by Gerenuk

  I'd like to write down the design of my program to understand the dependencies and calls better. I know there are class diagrams which show inheritance and attribute variables. However I'd also like to document the input parameters to method functions and in particular which calls the methods function executes inside (e.g. on the input parameters). Also sometimes it might be useful to show how actual objects are connected (if there is a standard structure). This way I can have a better understanding of the modules and design before starting to program. Can you suggest a method to do this software design? It should be one-to-one to programming code structure so that I really notice all quirks beforehand (instead of high-level design where thing are hard to implement without further work). Maybe some special diagram or tool or a combination? It is static dependency and call design rather than time dependent execution monitoring. (I use Python if you have any specialized recommendations).

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• Why implement DB connection pointer object as a reference counting pointer? (C++)

  - by DVK

  At our company one of the core C++ classes (Database connection pointer) is implemented as a reference counting pointer. To be clear, the objects are NOT DB connections themselves, but pointers to a DB connection object. The library is very old, and nobody who designed is around anymore. So far, nether I, nor any C++ experts in the company that I asked have come up with a good reason for why this particular design was chosen. Any ideas? It is introducing some problems (partially due to awful reference pointer implementation used), and I'm trying to understand if this design actually has some deep underlying reasons? The usage pattern these days seems to be that the DB connection pointer object is returned by a DB connection manager class, and it's somewhat unclear whether DB connection pointers were designed to be able to be used independently of DB connection manager.

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