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• Software Architecture: Quality Attributes

  Quality is what all software engineers should strive for when building a new system or adding new functionality. Dictonary.com ambiguously defines quality as a grade of excellence. Unfortunately, quality must be defined within the context of a situation in that each engineer must extract quality attributes from a project’s requirements. Because quality is defined by project requirements the meaning of quality is constantly changing base on the project. Software architecture factors that indicate the relevance and effectiveness The relevance and effectiveness of architecture can vary based on the context in which it was conceived and the quality attributes that are required to meet. Typically when evaluating architecture for a specific system regarding relevance and effectiveness the following questions should be asked.   Architectural relevance and effectiveness questions: Does the architectural concept meet the needs of the system for which it was designed? Out of the competing architectures for a system, which one is the most suitable? If we look at the first question regarding meeting the needs of a system for which it was designed. A system that answers yes to this question must meet all of its quality goals. This means that it consistently meets or exceeds performance goals for the system. In addition, the system meets all the other required system attributers based on the systems requirements. The suitability of a system is based on several factors. In order for a project to be suitable the necessary resources must be available to complete the task. Standard Project Resources: Money Trained Staff Time Life cycle factors that affect the system and design The development life cycle used on a project can drastically affect how a system’s architecture is created as well as influence its design. In the case of using the software development life cycle (SDLC) each phase must be completed before the next can begin.  This waterfall approach does not allow for changes in a system’s architecture after that phase is completed. This can lead to major system issues when the architecture for the system is not as optimal because of missed quality attributes. This can occur when a project has poor requirements and makes misguided architectural decisions to name a few examples. Once the architectural phase is complete the concepts established in this phase must move on to the design phase that is bound to use the concepts and guidelines defined in the previous phase regardless of any missing quality attributes needed for the project. If any issues arise during this phase regarding the selected architectural concepts they cannot be corrected during the current project. This directly has an effect on the design of a system because the proper qualities required for the project where not used when the architectural concepts were approved. When this is identified nothing can be done to fix the architectural issues and system design must use the existing architectural concepts regardless of its missing quality properties because the architectural concepts for the project cannot be altered. The decisions made in the design phase then preceded to fall down to the implementation phase where the actual system is coded based on the approved architectural concepts established in the architecture phase regardless of its architectural quality. Conversely projects using more of an iterative or agile methodology to implement a system has more flexibility to correct architectural decisions based on missing quality attributes. This is due to each phase of the SDLC is executed more than once so any issues identified in architecture of a system can be corrected in the next architectural phase. Subsequently the corresponding changes will then be adjusted in the following design phase so that when the project is completed the optimal architectural and design decision are applied to the solution. Architecture factors that indicate functional suitability Systems that have function shortcomings do not have the proper functionality based on the project’s driving quality attributes. What this means in English is that the system does not live up to what is required of it by the stakeholders as identified by the missing quality attributes and requirements. One way to prevent functional shortcomings is to test the project’s architecture, design, and implementation against the project’s driving quality attributes to ensure that none of the attributes were missed in any of the phases. Another way to ensure a system has functional suitability is to certify that all its requirements are fully articulated so that there is no chance for misconceptions or misinterpretations by all stakeholders. This will help prevent any issues regarding interpreting the system requirements during the initial architectural concept phase, design phase and implementation phase. Consider the applicability of other architectural models When considering an architectural model for a project is also important to consider other alternative architectural models to ensure that the model that is selected will meet the systems required functionality and high quality attributes. Recently I can remember talking about a project that I was working on and a coworker suggested a different architectural approach that I had never considered. This new model will allow for the same functionally that is offered by the existing model but will allow for a higher quality project because it fulfills more quality attributes. It is always important to seek alternatives prior to committing to an architectural model. Factors used to identify high-risk components A high risk component can be defined as a component that fulfills 2 or more quality attributes for a system. An example of this can be seen in a web application that utilizes a remote database. One high-risk component in this system is the TCIP component because it allows for HTTP connections to handle by a web server and as well as allows for the server to also connect to a remote database server so that it can import data into the system. This component allows for the assurance of data quality attribute and the accessibility quality attribute because the system is available on the network. If for some reason the TCIP component was to fail the web application would fail on two quality attributes accessibility and data assurance in that the web site is not accessible and data cannot be update as needed. Summary As stated previously, quality is what all software engineers should strive for when building a new system or adding new functionality. The quality of a system can be directly determined by how closely it is implemented when compared to its desired quality attributes. One way to insure a higher quality system is to enforce that all project requirements are fully articulated so that no assumptions or misunderstandings can be made by any of the stakeholders. By doing this a system has a better chance of becoming a high quality system based on its quality attributes

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• Design patter to keep track UITableView rows correspondance to underlying data in constant time.

  - by DenNukem

  When my model changes I want to animate changes in UITableView by inserting/deleting rows. For that I need to know the ordinal of the given row (so I can construct NSIndexPath), which I find hard to do in better-than-linear time. For example, consider that I have a list of addressbook entries which are manualy sorted by the user, i.e. there is no ordering "key" that represents the sort order. There is also a corresponding UITableView that shows one row per addressbook entry. When UITableView queries the datasource I query the NSMUtableArray populated with my entries and return required data in constant time for each row. However, if there is a change in underlying model I am getting a notification "Joe Smith, id#123 has been removed". Now I have a dilemma. A naive approach would be to scan the array, determine the index at which Joe Smith is and then ask UITableView to remove that precise row from the view, also removing it form the array. However, the scan will take linear time to finish. Now I could have an NSDictionary which allows me to find Joe Smith in constant time, but that doesn't do me a lot of good because I still need to find his ordinal index within the array in order to instruct UITableView to remove that row, which is again a linear search. I could further decide to store each object's ordinal inside the object itself to make it constant, but it will become outdated after first such update as all subsequent index values will have changed due to removal of an object. So what is the correct design pattern to accurately reflect model changes in the UITableView in costant (or at least logarithmic) time?

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• Why Java language does not offer a way to declare getters and setters of a given "field" through ann

  - by zim2001

  I actually happily design and develop JEE Applications for quite 9 years, but I realized recently that as time goes by, I feel more and more fed up of dragging all these ugly bean classes with their bunch of getters and setters. Considering a basic bean like this : public class MyBean { // needs getter AND setter private int myField1; // needs only a getter, no setter private int myField2; // needs only a setter, no getter private int myField3; /** * Get the field1 * @return the field1 */ public int getField1() { return myField1; } /** * Set the field1 * @param value the value */ public void setField1(int value) { myField1 = value; } /** * Get the field2 * @return the field2 */ public int getField2() { return myField2; } /** * Set the field3 * @param value the value */ public void setField3(int value) { myField3 = value; } } I'm dreaming of something like this : public class MyBean { @inout(public,public) private int myField1; @out(public) private int myField2; @in(public) private int myField3; } No more stupid javadoc, just tell the important thing... It would still be possible to mix annotation and written down getters or setters, to cover cases when it should do non-trivial sets and gets. In other words, annotation would auto-generate the getter / setter code piece except when a literate one is provided. Moreover, I'm also dreaming of replacing things like that : MyBean b = new MyBean(); int v = b.getField1(); b.setField3(v+1); by such : MyBean b = new MyBean(); int v = b.field1; b.field3 = v+1; In fact, writing "b.field1" on the right side of an expression would be semantically identical to write "b.getField1()", I mean as if it has been replaced by some kind of a preprocessor. It's just an idea but I'm wondering if I'm alone on that topic, and also if it has major flaws. I'm aware that this question doesn't exactly meet the SO credo (we prefer questions that can be answered, not just discussed) so I flag it community wiki...

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• "Illegal characters in path." Visual Studio WinForm Design View

  - by jacksonakj

  I am putting together a lightweight MVP pattern for a WinForms project. Everything compiles and runs fine. However when I attempt to open the WinForm in design mode in Visual Studio I get a "Illegal characters in path" error. My WinForm is using generics and inheriting from a base Form class. Is there a problem with using generics in a WinForm? Here is the WinForm and base Form class. public partial class TapsForm : MvpForm<TapsPresenter, TapsFormModel>, ITapsView { public TapsForm() { InitializeComponent(); } public TapsForm(TapsPresenter presenter) :base(presenter) { InitializeComponent(); UpdateModel(); } public IList<Taps> Taps { set { gridTaps.DataSource = value; } } private void UpdateModel() { Model.RideId = Int32.Parse(cboRide.Text); Model.Latitude = Double.Parse(txtLatitude.Text); Model.Longitude = Double.Parse(txtLongitude.Text); } } Base form MvpForm: public class MvpForm<TPresenter, TModel> : Form, IView where TPresenter : class, IPresenter where TModel : class, new() { private readonly TPresenter presenter; private TModel model; public MvpForm() { } public MvpForm(TPresenter presenter) { this.presenter = presenter; this.presenter.RegisterView(this); } protected override void OnLoad(EventArgs e) { base.OnLoad(e); if (presenter != null) presenter.IntializeView(); } public TModel Model { get { if (model == null) throw new InvalidOperationException("The Model property is currently null, however it should have been automatically initialized by the presenter. This most likely indicates that no presenter was bound to the control. Check your presenter bindings."); return model; } set { model = value;} } }

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• Write a compiler for a language that looks ahead and multiple files?

  - by acidzombie24

  In my language I can use a class variable in my method when the definition appears below the method. It can also call methods below my method and etc. There are no 'headers'. Take this C# example. class A { public void callMethods() { print(); B b; b.notYetSeen(); public void print() { Console.Write("v = {0}", v); } int v=9; } class B { public void notYetSeen() { Console.Write("notYetSeen()\n"); } } How should I compile that? what i was thinking is: pass1: convert everything to an AST pass2: go through all classes and build a list of define classes/variable/etc pass3: go through code and check if there's any errors such as undefined variable, wrong use etc and create my output But it seems like for this to work I have to do pass 1 and 2 for ALL files before doing pass3. Also it feels like a lot of work to do until I find a syntax error (other than the obvious that can be done at parse time such as forgetting to close a brace or writing 0xLETTERS instead of a hex value). My gut says there is some other way. Note: I am using bison/flex to generate my compiler.

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• Should we have a database independent SQL like query language in Django? [closed]

  - by Yugal Jindle

  Note : I know we have Django ORM already that keeps things database independent and converts to the database specific SQL queries. Once things starts getting complicated it is preferred to write raw SQL queries for better efficiency. When you write raw sql queries your code gets trapped with the database you are using. I also understand its important to use the full power of your database that can-not be achieved with the django orm alone. My Question : Until I use any database specific feature, why should one be trapped with the database. For instance : We have a query with multiple joins and we decided to write a raw sql query. Now, that makes my website postgres specific. Even when I have not used any postgres specific feature. I feel there should be some fake sql language which can translate to any database's sql query. Even Django's ORM can be built over it. So, that if you go out of ORM but not database specific - you can still remain database independent. I asked the same question to Jacob Kaplan Moss (In person) : He advised me to stay with the database that I like and endure its whole power, to which I agree. But my point was not that we should be database independent. My point is we should be database independent until we use a database specific feature. Please explain, why should be there a fake sql layer over the actual sql ?

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• How to Set Customer Table with Multiple Phone Numbers? - Relational Database Design

  - by user311509

  CREATE TABLE Phone ( phoneID - PK . . . ); CREATE TABLE PhoneDetail ( phoneDetailID - PK phoneID - FK points to Phone phoneTypeID ... phoneNumber ... . . . ); CREATE TABLE Customer ( customerID - PK firstName phoneID - Unique FK points to Phone . . . ); A customer can have multiple phone numbers e.g. Cell, Work, etc. phoneID in Customer table is unique and points to PhoneID in Phone table. If customer record is deleted, phoneID in Phone table should also be deleted. Do you have any concerns on my design? Is this designed properly? My problem is phoneID in Customer table is a child and if child record is deleted then i can not delete the parent (Phone) record automatically.

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• Design pattern to keep track UITableView rows correspondance to underlying data in constant time.

  - by DenNukem

  When my model changes I want to animate changes in UITableView by inserting/deleting rows. For that I need to know the ordinal of the given row (so I can construct NSIndexPath), which I find hard to do in better-than-linear time. For example, consider that I have a list of addressbook entries which are manualy sorted by the user, i.e. there is no ordering "key" that represents the sort order. There is also a corresponding UITableView that shows one row per addressbook entry. When UITableView queries the datasource I query the NSMUtableArray populated with my entries and return required data in constant time for each row. However, if there is a change in underlying model I am getting a notification "Joe Smith, id#123 has been removed". Now I have a dilemma. A naive approach would be to scan the array, determine the index at which Joe Smith is and then ask UITableView to remove that precise row from the view, also removing it form the array. However, the scan will take linear time to finish. Now I could have an NSDictionary which allows me to find Joe Smith in constant time, but that doesn't do me a lot of good because I still need to find his ordinal index within the array in order to instruct UITableView to remove that row, which is again a linear search. I could further decide to store each object's ordinal inside the object itself to make it constant, but it will become outdated after first such update as all subsequent index values will have changed due to removal of an object. So what is the correct design pattern to accurately reflect model changes in the UITableView in costant (or at least logarithmic) time?

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• RESTful design, how to name pages outside CRUD et al?

  - by sscirrus

  Hi all, I'm working on a site that has quite a few pages that fall outside my limited understanding of RESTful design, which is essentially: Create, Read, Update, Delete, Show, List Here's the question: what is a good system for labeling actions/routes when a page doesn't neatly fall into CRUD/show/list? Some of my pages have info about multiple tables at once. I am building a site that gives some customers a 'home base' after they log on. It does NOT give them any information about themselves so it shouldn't be, for example, /customers/show/1. It does have information about companies, but there are other pages on the site that do that differently. What do you do when you have these situations? This 'home-base' is shown to customers and it mainly has info about companies (but not uniquely so). Second case: I have a table called 'Matchings' in between customers and companies. These matchings are accessed in completely different ways on different parts of the site (different layouts, different CSS sheets, different types of users accessing them, etc. They can't ALL be matchings/show. What's the best way to label the others? Thanks very much. =)

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• Hybrid EAV/CR model via WCF (and statically-typed language)?

  - by Pat

  Background I'm working on the architecture for a cloud-based LOB application, using Silverlight for the client, WCF, ASP.NET/C# for server and SQL Server for storage. The data model requires some flexibility per user (ability to add custom properties and define validation rules for them, for example), and a hybrid EAV/CR persistence model on the server side will suit nicely. Problem I need an efficient and maintainable technology and approach to handle the transformation from the persisted EAV model to/from WCF (and similarly allow the client to bind to the resulting data - DataGrid is a key UI element)? Admission: I don't yet know enough about WCF to understand if it supports ExpandoObject directly, but I suspect it will. Options I started off looking at WCF RIA services, but quickly discovered they're heavily dependent upon both static type data and compile-time code generation. Neither of these appeal. The options I'm considering include: Using WCF RIA services and pass the data over the network directly in EAV form (i.e. Dictionary), and handle the binding issue purely on the client side (like this) Using a dynamic language (probably IronPython) to handle both ends of the communication, with plumbing to generate the necessary CLR type data on the client to allow binding, and transform to/from EAV form on the server (spam preventer stopped me from posting a URL here, I'll try it in a comment). Dynamic LINQ (CreateClass() and friends), although I'm way out of my depth there and don't know what the limitations on that approach might be yet. I'm interested in comments on these approaches as well as alternative approaches that might solve the problem. Other Notes The Silverlight client will not be the only consumer of the service, making me slightly uncomfortable with option #1 above. While the data model is flexible, it's not expected to be modified heavily. For argument's sake, we could assume that we might have 25 distinct data models active at a given time, with something like 10-20 unique data fields/rules each. Modifications to the data model will happen infrequently (typically when a new user is initially configured).

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• How to design Models the correct way: Object-oriented or "Package"-oriented?

  - by ajsie

  I know that in OOP you want every object (from a class) to be a "thing", eg. user, validator etc. I know the basics about MVC, how they different parts interact with each other. However, i wonder if the models in MVC should be designed according to the traditional OOP design, that is to say, should every model be a database/table/row (solution 2)? Or is the intention more like to collect methods that are affecting the same table or a bunch of related tables (solution 1). example for an Address book module in CodeIgniter, where i want be able to "CRUD" a Contact and add/remove it to/from a CRUD-able Contact Group. Models solution 1: bunching all related methods together (not real object, rather a "package") class Contacts extends Model { function create_contact() {) function read_contact() {} function update_contact() {} function delete_contact() {} function add_contact_to_group() {} function delete_contact_from_group() {} function create_group() {} function read_group() {} function update_group() {} function delete_group() {} } Models solution 2: the OOP way (one class per file) class Contact extends Model { private $name = ''; private $id = ''; function create_contact() {) function read_contact() {} function update_contact() {} function delete_contact() {} } class ContactGroup extends Model { private $name = ''; private $id = ''; function add_contact_to_group() {} function delete_contact_from_group() {} function create_group() {} function read_group() {} function update_group() {} function delete_group() {} } i dont know how to think when i want to create the models. and the above examples are my real tasks for creating an Address book. Should i just bunch all functions together in one class. then the class contains different logic (contact and group), so it can not hold properties that are specific for either one of them. the solution 2 works according to the OOP. but i dont know why i should make such a dividing. what would the benefits be to have a Contact object for example. Its surely not a User object, so why should a Contact "live" with its own state (properties and methods). you experienced guys with OOP/MVC, please shed a light on how one should think here in this very concrete task.

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• What is a good programming language/environment for Linux database applications?

  - by Dkellygb

  I could use some advice on my move from the Windows world to Linux. For my business, I have used VB6 and Microsoft Access with both Access databases and SQL server in the past. The easy to use forms, report writers and programming language were perfect for CRUD apps and analysis for our small hotel/restaurant business. After using Linux at home for some time I would like to convert our small business. Our server is already a Linux box using Samba. I am happy with the OpenOffice.org applications instead of Microsoft Office. The only thing which is holding me back is a desktop database application where I can develop the forms and reports we require. Base does not seem to be up to the job yet from my experience. I would like something like VB.Net with visual studio (express) but I would like to avoid Mono – I just don’t see the point of it. (You can correct me if I’m wrong.) But a good collection of forms, controls and a good report writer would be ideal. I have looked at web based stuff like Ruby on Rails, but I think a webserver for our 5 pc network is overkill. I don’t mind running a proper database on our Ubuntu 9.10 server. I may have exposed a few prejudices above but my mind is open. Any thoughts?

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• Design PDF template and populate data at runtime using java,xml etc..

  - by Samant

  well i have been looking for a java based PDF solutions...we dont have a clean way i guess-still.. all solutions are primitive and kind of workarounds... No easy solution for this requirement - 1. Designing a PDF template using a IDE (eg. Livecycle designer ..which is not free) 2. Then at runtime using java, populate data into this PDF template...either using xml or other datasources... such a simple requirement and NONE has a good "open-source and free" solution yet ! Is anyone aware of any ? I have been searching for since 3-4 years now..for a clean way out... Eclipse BIRT comes close.. but does not handle Barcode elements ..OOB. Jasper - ireport is also good but that tool does not have a table concept and is kind of annoying ! Also barcode support is not good. XSL-FO has not free IDE for design . Looking for a better answer .. got one ?

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• How to simplify this code or a better design?

  - by Tattat

  I am developing a game, the game have different mode. Easy, Normal, and Difficult. So, I'm thinking about how to store the game mode. My first idea is using number to represent the difficulty. Easy = 0 Normal = 1 Difficult = 2 So, my code will have something like this: switch(gameMode){ case 0: //easy break; case 1: //normal break; case 3: //difficult break; } But I think it have some problems, if I add a new mode, for example, "Extreme", I need to add case 4... ... it seems not a gd design. So, I am thinking making a gameMode object, and different gameMode is sub class of the super class gameMode. The gameMode object is something like this: class GameMode{ int maxEnemyNumber; int maxWeaponNumber; public static GameMode init(){ GameMode gm = GameMode(); gm.maxEnemyNumber = 0; gm.maxWeaponNumber = 0; return gm; } } class EasyMode extends GameMode{ public static GameMode init(){ GameMode gm = super.init(); gm.maxEnemyNumber = 10; gm.maxWeaponNumber = 100; return gm; } } class NormalMode extends GameMode{ public static GameMode init(){ GameMode gm = super.init(); gm.maxEnemyNumber = 20; gm.maxWeaponNumber = 80; return gm; } } But I think it seems too "bulky" to create an object to store gameMode, my "gameMode" only store different variables for game settings.... Is that any simple way to store data only instead of making an Object? thz u.

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• Java OO design confusion: how to handle actions modified by states modified by actions...

  - by Arvanem

  Hi folks, Given an entity, whose action is potentially modified by states (of the entity and other entities) in turn potentially modified by other actions (of the entity and other entities) , what is the best way to code or design to handle the potential existence of the modifiers? Speaking metaphorically, I am coding a Java application representing a piano. As you know a piano has keys (which, when pressed, emit sound) and pedals (which, when pressed, modify the keys' sounds). My base class structure is as follows: Entity (for keys and pedals) State (this holds each entity's states, e.g. name such as "soft pedal", and boolean "Pressed"), Action (this holds each entity's actions, e.g. play sound when pressed, or modify others sounds). By composition, the Entity class has a copy of each of State and Action inside it. e.g.: public class Entity { State entityState = new State(); Action entityAction = new Action(); Thus I have coded a "C-Sharp" key Entity. When I "press" that entity (set its "Pressed" state to true), its action plays a "C-Sharp" sound and then sets its "Pressed" state to false. At the same time, if the "C-Sharp" key entity is not "tuned", its sound deviates from "C-Sharp". Meanwhile I have coded a "soft pedal" Entity. When that entity is "pressed", no sound plays but its action is to make softer the sound of the "C-Sharp" and other key entities. I have also coded a "sustain pedal" Entity. When that entity is "pressed", no sound plays but its action is to enable reverberation of the sound of the "C-Sharp" and other key entities. Both the "soft" and "sustain pedals" can be pressed at the same time with the result that keys entities become both softened and reverberating. In short, I do not understand how to make this simultaneous series of states and actions modify each other in a sensible OO way. I am wary of coding a massive series of "if" statements or "switches". Thanks in advance for any help or links you can offer.

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• What Color is the Windows' System.Control? (Visual Studio Design View)

  - by jp2code

  In Visual Studio Design View, the selection of Form Colors in the Properties Pane are selectable from the "Custom", "Web", and "System" tabs. Of course, the color number can be used, too. When the "System" Tab is selected, the colors in the list depend on what type of Theme the Computer User has set on the PC. I'd like to stick with this, but I need to know how to "read in" the colors. I have controls that I create "on-the-fly" or often need to change a color back after getting the person's attention using a blink/flicker technique. How do I get the list of System Theme colors? Most forms have a BackColor that defaults to "Control", which looks like a very light gray under Windows 7, running the default Windows 7 Theme. I've managed to grab a color by physically reading the ARGB value in code, but I'd rather have a way to access the colors by their Theme Name, if that can be done. public Form1() { Color cControl = this.BackColor; Console.WriteLine(cControl.Name); // there is not always a name! } Does anyone know what I'm talking about?

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• How do I add the go language to gitg's list of viewable sources?

  - by Hotei

  Hoping a 'git' guru will help out here. I am just beginning to "git" for the first time and have (among other things :-) ) git and gitg installed from Ubuntu 10.4 / AMD64 distribution (ie. maybe not 'latest' version but not ancient). I am trying to look at the go code I've committed via gitg and in the "tree tab" it says :Cannot display file content as text. However, the "details tab" shows the diffs of the same file just fine. I know gitg's "tree tab" is working because I can use the tree view on *.c / *.html / *.txt etc just fine. Is there a way to tweak gitg into understanding that "*.go" is just text? A little more context: Installed gitg version is 0.0.5 - ie a version behind latest - 0.0.6 - source of which I am looking thru now. I do have a working /usr/share/gtksourceview-2.0/language-specs/ go.lang. It works just fine as highlighter in gedit. It appears that gitg may require displayable files to have a mime type of "text/plain", so I added that to go.lang No joy. gitg still fails on *.go I'm relatively sure the fix is simple, just don't know where to look.

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• C#: at design time, how can I reliably determine the type of a variable that is declared using var?

  - by Cheeso

  I'm working on a completion (intellisense) facility for C# in emacs. The idea is, if a user types a fragment, then asks for completion via a particular keystroke combination, the completion facility will use .NET reflection to determine the possible completions. Doing this requires that the type of the thing being completed, be known. If it's a string, it has a set of known methods; if it's an Int32, it has a separate set of methods, and so on. Using semantic, a code lexer/parser package available in emacs, I can locate the variable declarations, and their types. Given that, it's straightforward to use reflection to get the methods and properties on the type, and then present the list of options to the user. The problem arrives when the code uses var in the declaration. How can I reliably determine the actual type used, when the variable is declared with the var keyword? Just to be clear, I don't need to determine it at runtime. I want to determine it at "Design time". So far the best idea I have is: extract the declaration statement, eg var foo = "a string value"; concatenate a statement foo.GetType(); dynamically compile the resulting C# fragment it into a new assembly load the assembly into a new AppDomain, run the framgment and get the return type. unload and discard the assembly This sounds awfully heavyweight, for each completion request in the editor. Any better ideas out there?

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• Mis-spelling in the .NET configuration system, a design flaw?

  - by smwikipedia

  I just wrote some .NET code to get connection string from the config file. The config file is as below: <?xml version="1.0" encoding="utf-8" ?> <configuration> <appSettings> <add key="key1" value="hello,world!"/> </appSettings> <connectionStrings> <add name="conn1" connectionString="abcd"/> </connectionStrings> </configuration> .NET Framework provide the following types to get the connection string: 1- ConnectionStringsSection : stands for the config section containing several connection strings 2- ConnectionStringSettingsCollection : stands for the connection string collection 3- ConnectionStringSettings : stands for a certain connection string. .NET Framework also provide the following types to get the App Settings: 4- AppSettingsSection 5- KeyValueConfigurationCollection 6- KeyValueConfigurationElement Compare 2 to 5, 3 to 6, why are there extra "s" in ConnectionStringSetting[s]Collection and ConnectionStringSetting[s]? This mis-spelling is really mis-leading. I think it's a design flaw. Has anyone noticed that?

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• Are vector assignments copied by value or by reference in Google's Go language?

  - by Brian T Hannan

  In the following code, I create one peg puzzle then do a move on it which adds a move to its movesAlreadyDone vector. Then I create another peg puzzle then do a move on it which adds a move to its movesAlreadyDone vector. When I print out the values in that vector for the second one, it has the move in it from the first one along with the move from the second one. Can anyone tell me why it seems to be assigning by reference and not value? Are vector assignments copied by value or by reference in Google's Go language? package main import "fmt" import "container/vector" type Move struct { x0, y0, x1, y1 int } type PegPuzzle struct { movesAlreadyDone * vector.Vector; } func (p *PegPuzzle) InitPegPuzzle(){ p.movesAlreadyDone = vector.New(0); } func NewChildPegPuzzle(parent *PegPuzzle) *PegPuzzle{ retVal := new(PegPuzzle); retVal.movesAlreadyDone = parent.movesAlreadyDone; return retVal } func (p *PegPuzzle) doMove(move Move){ p.movesAlreadyDone.Push(move); } func (p *PegPuzzle) printPuzzleInfo(){ fmt.Printf("-----------START----------------------\n"); fmt.Printf("moves already done: %v\n", p.movesAlreadyDone); fmt.Printf("------------END-----------------------\n"); } func main() { p := new(PegPuzzle); cp1 := new(PegPuzzle); cp2 := new(PegPuzzle); p.InitPegPuzzle(); cp1 = NewChildPegPuzzle(p); cp1.doMove(Move{1,1,2,3}); cp1.printPuzzleInfo(); cp2 = NewChildPegPuzzle(p); cp2.doMove(Move{3,2,5,1}); cp2.printPuzzleInfo(); } Any help will be greatly appreciated. Thanks!

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• How can i design a DB where the user can define the fields and types of a detail table in a M-D rela

  - by Simon

  My application has one table called 'events' and each event has approx 30 standard fields, but also user defined fields that could be any name or type, in an 'eventdata' table. Users can define these event data tables, by specifying x number of fields (either text/double/datetime/boolean) and the names of these fields. This 'eventdata' (table) can be different for each 'event'. My current approach is to create a lookup table for the definitions. So if i need to query all 'event' and 'eventdata' per record, i do so in a M-D relaitionship using two queries (i.e. select * from events, then for each record in 'events', select * from 'some table'). Is there a better approach to doing this? I have implemented this so far, but most of my queries require two distinct calls to the DB - i cannot simply join my master 'events' table with different 'eventdata' tables for each record in in 'events'. I guess my main question is: can i join my master table with different detail tables for each record? E.g. SELECT E.*, E.Tablename FROM events E LEFT JOIN 'E.tablename' T ON E._ID = T.ID If not, is there a better way to design my database considering i have no idea on how many user defined fields there may be and what type they will be.

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• Need a design approach or suggestion for a simple structure using Servlet.

  - by akshay

  Hi I have to design such that whenever user pass a query I process it using servlet and then call the js page to draw the chart 1 user writes a query on a page 2 the page call the servelt class public class MyServlet extends Httpservlet implements DataSourceServlet {..... return data The user see a beautiful string like this.. google.visualization.Query.setResponse......... /Tiger'},{v:80.0}, {v:false}]}]}}); 3 when the user hits on different html page myhtml.js it draws the chart. I want the Myservlet class itself call the myhtml.js page and draw the chart directly. and want to eliminate the beautiful string google.visualization.Query.setResponse......... /Tiger'},{v:80.0}, {v:false}]}]}}); from coming on user's browser What should i do? I tried using functions to call another page like request dispatcher(), redirect() calling myhtml.js page directly after myservlet process the query results. But i get the result like this google.visualization.Query.setResponse......... /Tiger'},{v:80.0}, {v:false}]}]}}); and the entire myhtml.js code page below it on the browsers that to without the chart been draw. Is there anyway to element the beautiful string from coming on clients browser and only show them the chart been drawn ? :) This is the small tutorial i am following http://code.google.com/apis/visualization/documentation/dev/dsl_get_started.html

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• Is Prolog the best language to solve this kind of problem?

  - by Milan Babuškov

  I have this problem containing some inequations and requirement to minimize a value. After doing some research on the Internet, I came to conclusion that using Prolog might be the easiest way to solve it. However, I never used Prolog before, and I would hate to waste my time learning it just to discover that it is not the right tool for this job. Please, if you know Prolog, take a look at this problem and tell me if Prolog is the right one. Or, if you know of some other language that is really suited for this. a + b + c >= 100 d + e + f >= 50 g + h >= 30 if (8b + 2e + 7h > 620) then y = 0.8 else y = 1.0 if (d > 35) then x = 0.9 else x = 1.0 5xa + 8yb + 5c + 3xd + 2ye + 2f + 6xg + 7yh = w. I need to find the values for a, b, c, d, e, f, g and h that minimize w. I'm not really asking for code, although I'd be grateful for some hint how to tackle this if Prolog is really good for it. Thanks.

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• What would be the Better db design for the old db structure?

  - by yawok

  i've a old database where i store the data of the holidays and dates in which they are celebrated.. id country hdate description link 1 Afghanistan 2008-01-19 Ashura ashura 2 Albania 2008-01-01 New Year Day new-year the flaws in the above structure is that, i repeat the data other than date for every festival and every year and every country.. For example, I store a new date for 2009 for ashura and afghanistan .. I tried to limit the redundancy and split the tables as countries (id,name) holidays (id, holiday, celebrated_by, link) // celebrated_by will store the id's of countries separated by ',' holiday_dates (holiday_id, date, year) // date will the full date and year will be as 2008 or 2009 Now i have some problems with the structure too.. consider that i store the holiday like Independence day , its common for more countries but will have different dates. so how to handle this and and the link will have to be different too.. And i need to list the countries which celebrates the same holiday and also when i describe about a single holiday i need to list all the other holidays that country would be celebrating.. And the most of all , i already have huge amount of data in the old tables and i need to split it to the new one once the new design is finalized... Any ideas?

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• Configuring varnish and django (apache/modwsgi)

  - by Hedde

  I am trying to work out why my application keeps hitting the database while I have setup varnish infront of apache. I think I am missing some vital configuration, any tips are welcome This is my curl result: HTTP/1.1 200 OK Server: Apache/2.2.16 (Debian) Content-Language: en-us Vary: Accept,Accept-Encoding,Accept-Language,Cookie Cache-Control: s-maxage=60, no-transform, max-age=60 Content-Type: application/json; charset=utf-8 Date: Sat, 15 Sep 2012 08:19:17 GMT Connection: keep-alive My varnishlog: 13 BackendClose - apache 13 BackendOpen b apache 127.0.0.1 47665 127.0.0.1 8000 13 TxRequest b GET 13 TxURL b /api/v1/events/?format=json 13 TxProtocol b HTTP/1.1 13 TxHeader b User-Agent: curl/7.19.7 (universal-apple-darwin10.0) libcurl/7.19.7 OpenSSL/0.9.8r zlib/1.2.3 13 TxHeader b Host: foobar.com 13 TxHeader b Accept: */* 13 TxHeader b X-Forwarded-For: 92.64.200.145 13 TxHeader b X-Varnish: 979305817 13 TxHeader b Accept-Encoding: gzip 13 RxProtocol b HTTP/1.1 13 RxStatus b 200 13 RxResponse b OK 13 RxHeader b Date: Sat, 15 Sep 2012 08:21:28 GMT 13 RxHeader b Server: Apache/2.2.16 (Debian) 13 RxHeader b Content-Language: en-us 13 RxHeader b Content-Encoding: gzip 13 RxHeader b Vary: Accept,Accept-Encoding,Accept-Language,Cookie 13 RxHeader b Cache-Control: s-maxage=60, no-transform, max-age=60 13 RxHeader b Content-Length: 6399 13 RxHeader b Content-Type: application/json; charset=utf-8 13 Fetch_Body b 4(length) cls 0 mklen 1 13 Length b 6399 13 BackendReuse b apache 11 SessionOpen c 92.64.200.145 53236 :80 11 ReqStart c 92.64.200.145 53236 979305817 11 RxRequest c HEAD 11 RxURL c /api/v1/events/?format=json 11 RxProtocol c HTTP/1.1 11 RxHeader c User-Agent: curl/7.19.7 (universal-apple-darwin10.0) libcurl/7.19.7 OpenSSL/0.9.8r zlib/1.2.3 11 RxHeader c Host: foobar.com 11 RxHeader c Accept: */* 11 VCL_call c recv lookup 11 VCL_call c hash 11 Hash c /api/v1/events/?format=json 11 Hash c foobar.com 11 VCL_return c hash 11 VCL_call c miss fetch 11 Backend c 13 apache apache 11 TTL c 979305817 RFC 60 -1 -1 1347697289 0 1347697288 0 60 11 VCL_call c fetch deliver 11 ObjProtocol c HTTP/1.1 11 ObjResponse c OK 11 ObjHeader c Date: Sat, 15 Sep 2012 08:21:28 GMT 11 ObjHeader c Server: Apache/2.2.16 (Debian) 11 ObjHeader c Content-Language: en-us 11 ObjHeader c Content-Encoding: gzip 11 ObjHeader c Vary: Accept,Accept-Encoding,Accept-Language,Cookie 11 ObjHeader c Cache-Control: s-maxage=60, no-transform, max-age=60 11 ObjHeader c Content-Type: application/json; charset=utf-8 11 Gzip c u F - 6399 69865 80 80 51128 11 VCL_call c deliver deliver 11 TxProtocol c HTTP/1.1 11 TxStatus c 200 11 TxResponse c OK 11 TxHeader c Server: Apache/2.2.16 (Debian) 11 TxHeader c Content-Language: en-us 11 TxHeader c Vary: Accept,Accept-Encoding,Accept-Language,Cookie 11 TxHeader c Cache-Control: s-maxage=60, no-transform, max-age=60 11 TxHeader c Content-Type: application/json; charset=utf-8 11 TxHeader c Date: Sat, 15 Sep 2012 08:21:29 GMT 11 TxHeader c Connection: keep-alive 11 Length c 0 11 ReqEnd c 979305817 1347697288.292612076 1347697289.456128597 0.000086784 1.163468122 0.000048399

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