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• Best practice for near reuse of model components?

  - by Chris Knight

  I have a requirement to use a Fund model in my code. It will contain a fund name and fund code. In the interest of reuse I've poked around the package containing the other models used and found an existing Fund model. However the issue here is that, in addition to fund name and code, it also contains an amount. Amount isn't directly relevant in my context. So, do I: 1) Use the existing Fund model as is, ignoring the setters/getters for fund amount. 2) Put a FundDescription interface onto the existing Fund model for accessing only the information I'm interested in. 3) Make a FundDescription base class from which the existing Fund model could now extend 4) Create a whole new seperate model since the two are slightly contextually different

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• Is it a good idea to define a variable in a local block for a case of a switch statement?

  - by Paperflyer

  I have a rather long switch-case statement. Some of the cases are really short and trivial. A few are longer and need some variables that are never used anywhere else, like this: switch (action) { case kSimpleAction: // Do something simple break; case kComplexAction: { int specialVariable = 5; // Do something complex with specialVariable } break; } The alternative would be to declare that variable before going into the switch like this: int specialVariable = 5; switch (action) { case kSimpleAction: // Do something simple break; case kComplexAction: // Do something complex with specialVariable break; } This can get rather confusing since it is not clear to which case the variable belongs and it uses some unnecessary memory. However, I have never seen this usage anywhere else. Do you think it is a good idea to declare variables locally in a block for a single case?

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• Should I use block identifiers ("end;") in my code?

  - by JosephStyons

  Code Complete says it is good practice to always use block identifiers, both for clarity and as a defensive measure. Since reading that book, I've been doing that religiously. Sometimes it seems excessive though, as in the case below. Is Steve McConnell right to insist on always using block identifiers? Which of these would you use? //naughty and brief with myGrid do for currRow := FixedRows to RowCount - 1 do if RowChanged(currRow) then if not(RecordExists(currRow)) then InsertNewRecord(currRow) else UpdateExistingRecord(currRow); //well behaved and verbose with myGrid do begin for currRow := FixedRows to RowCount - 1 do begin if RowChanged(currRow) then begin if not(RecordExists(currRow)) then begin InsertNewRecord(currRow); end //if it didn't exist, so insert it else begin UpdateExistingRecord(currRow); end; //else it existed, so update it end; //if any change end; //for each row in the grid end; //with myGrid

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• Is this multi line if statement too complex?

  - by AndHeCodedIt

  I am validating input on a form and attempting to prompt the user of improper input(s) based on the combination of controls used. For example, I have 2 combo boxes and 3 text boxes. The 2 combo boxes must always have a value other than the first (default) value, but one of three, or two of three, or all text boxes can be filled to make the form valid. In one such scenario I have a 6 line if statement to try to make the test easily readable: if ((!String.Equals(ComboBoxA.SelectedValue.ToString(), DEFAULT_COMBO_A_CHOICE.ToString()) && !String.IsNullOrEmpty(TextBoxA.Text) && !String.Equals(ComboBoxB.SelectedValue.ToString(), DEFAULT_COMBO_B_CHOICE.ToString())) || (!String.IsNullOrEmpty(TextBoxB.Text) || !String.IsNullOrEmpty(TextBoxC.Text))) { //Do Some Validation } I have 2 questions: Should this type of if statement be avoided at all cost? Would it be better to enclose this test in another method? (This would be a good choice as this validation will happen in more than one scenario) Thanks for your input(s)!

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• Processing forms that generate many rows in DB

  - by Zack

  I'm wondering what the best approach to take here is. I've got a form that people use to register for a class and a lot of times the manager of a company will register multiple people for the class at the same time. Presently, they'd have to go through the registration process multiple times and resubmit the form once for every person they want to register. What I want to do is give the user a form that has a single <input/> for one person to register with, along with all the other fields they'll need to fill out (Email, phone number, etc); if they want to add more people, they'll be able to press a button and a new <input/> will be generated. This part I know how to do, but I'm including it to best describe what I'm aiming to do. The part I don't know how to approach is processing that data the form submits, I need some way of making a new row in the Registrant table for every <input/> that's added and include the same contact information (phone, email, etc) as the first row with that row. For the record, I'm using the Django framework for my back-end code. What's the best approach here? Should it just POST the form x times for x people, or is there a less "brute force" way of handling this?

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• Files mapping architecture

  - by user326198

  I need to know How I can achieve this goal by classes : we have two different applications in the company (App1 , App2) Appl can export xml with know items ( ID , Name) we need app2 to import this data but App2 display different items (CarID, CarName) and this items defined like this with the mapping info <CarID> <Mapping name="ID"/> </CarID> <CarNAme> <Mapping name="Name"/> </CarNAme>" How I can achieve this as classes or ARCHITECTURE , i will develop this with c# I need one interface because we may support different type of files not just xml

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• Comparing objects and inheritance

  - by ereOn

  Hi, In my program I have the following class hierarchy: class Base // Base is an abstract class { }; class A : public Base { }; class B : public Base { }; I would like to do the following: foo(const Base& one, const Base& two) { if (one == two) { // Do something } else { // Do something else } } I have issues regarding the operator==() here. Of course comparing an instance A and an instance of B makes no sense but comparing two instances of Base should be possible. (You can't compare a Dog and a Cat however you can compare two Animals) I would like the following results: A == B = false A == A = true or false, depending on the effective value of the two instances B == B = true or false, depending on the effective value of the two instances My question is: is this a good design/idea ? Is this even possible ? What functions should I write/overload ? My apologies if the question is obviously stupid or easy, I have some serious fever right now and my thinking abilities are somewhat limited :/ Thank you.

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• How to send complete POST to Model in Code Igniter

  - by Constant M

  Hi there, What would be the best way to send a complete post to a model in Code Igniter? Methods I know are as follow: Name form elements as array, eg. <input type="text" name="contact[name]"> <input type="text" name="contact[surname]"> and then use: $this->Model_name->add_contact($this->input->post('contact')); The other would be to add each element to an array and then send it to the model as such: <input type="text" name="name"> <input type="text" name="surname"> and $contact_array = array('name' => $this->input->post('name'), 'surname' => $this->input->post('surname')); $this->Model_name->add_contact($this->input->post('contact')); Which one of these would be best practice, and is there a way to directly send a whole POST to a model (or a whole form maybe?)

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• What is the role of the Router Object in MVC based frameworks

  - by Saif Bechan

  In most MVC based framework I see a router object. If I look at it splits up the uri and decides what controller should be used, and which action should be fired. Even though this makes a lot of sense, I can not give this a place in the MVC patern. Is splitting up the uri not the job of the controller. And then the controller should just decide which class and function to run.

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• Passing arguments between classes - use public properties or pass a properties class as argument?

  - by devoured elysium

  So let's assume I have a class named ABC that will have a list of Point objects. I need to make some drawing logic with them. Each one of those Point objects will have a Draw() method that will be called by the ABC class. The Draw() method code will need info from ABC class. I can only see two ways to make them have this info: Having Abc class make public some properties that would allow draw() to make its decisions. Having Abc class pass to draw() a class full of properties. The properties in both cases would be the same, my question is what is preferred in this case. Maybe the second approach is more flexible? Maybe not? I don't see here a clear winner, but that sure has more to do with my inexperience than any other thing. If there are other good approaches, feel free to share them. Here are both cases: class Abc1 { public property a; public property b; public property c; ... public property z; public void method1(); ... public void methodn(); } and here is approach 2: class Abc2 { //here we make take down all properties public void method1(); ... public void methodn(); } class Abc2MethodArgs { //and we put them here. this class will be passed as argument to //Point's draw() method! public property a; public property b; public property c; ... public property z; } Also, if there are any "formal" names for these two approaches, I'd like to know them so I can better choose the tags/thread name, so it's more useful for searching purposes. That or feel free to edit them.

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• LINQ to SQL - Lightweight O/RM?

  - by CoffeeAddict

  I've heard from some that LINQ to SQL is good for lightweight apps. But then I see LINQ to SQL being used for Stackoverflow, and a bunch of other .coms I know (from interviewing with them). Ok, so is this true? for an e-commerce site that's bringing in millions and you're typically only doing basic CRUDs most the time with the exception of an occasional stored proc for something more complex, is LINQ to SQL complete enough and performance-wise good enough or able to be tweaked enough to run happily on an e-commerce site? I've heard that you just need to tweak performance on the DB side when using LINQ to SQL for a better approach. So there are really 2 questions here: 1) Meaning/scope/definition of a "Lightweight" O/RM solution: What the heck does "lightweight" mean when people say LINQ to SQL is a "lightweight O/RM" and is that true??? If this is so lightweight then why do I see a bunch of huge .coms using it? Is it good enough to run major .coms (obviously it looks like it is) and what determines what the context of "lightweight" is...it's such a generic statement. 2) Performance: I'm working on my own .com and researching different O/RMs. I'm not really looking at the Entity Framework (yet), just want to figure out the LINQ to SQL basics here and determine if it will be efficient enough for me. The problem I think is you can't tweak or control the SQL it generates...

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• best practice when referring to a program's name in C

  - by guest

  what is considered best practice when referring to a program's name? i've seen #define PROGRAM_NAME "myprog" printf("this is %s\n", PROGRAM_NAME); as well as printf("this is %s\n", argv[0]); i know, that the second approach will give me ./myprog rather than myprog when the program is not called from $PATH and that the first approach will guarantee consistence regarding the program's name. but is there anything else, that makes one approach superior to the other?

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• Should every class have its own namespace?

  - by thehouse

  Something that has been troubling me for a while: The current wisdom is that types should be kept in a namespace that only contains functions which are part of the type's non-member interface (see C++ Coding Standards Sutter and Alexandrescu or here) to prevent ADL pulling in unrelated definitions. Does this imply that all classes must have a namespace of their own? If we assume that a class may be augmented in the future by the addition of non-member functions, then it can never be safe to put two types in the same namespace as either one of them may introduce non-member functions that could interfere with the other. The reason I ask is that namespaces are becoming cumbersome for me. I'm writing a header-only library and I find myself using classes names such as project::component::class_name::class_name. Their implementations call helper functions but as these can't be in the same namespace they also have to be fully qualified!

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• how to implement this observer pattern?

  - by lethal

  Hello. I have 4 classes, that describe state diagram. Node, Edge, ComponentOfNode, ComponentOfEdge. ComponentOfEdge compounds from ComponentsOfNode. Node can have 0..n outgoing edges. Edge can have only 2 nodes. Edge should be able to offer ComponentOfNode, but only from nodes that Edge has, in form ComponentOfEdge. The user can change ComponentsOfNode. I need this change spreads to all Edge. Hw to do it? I expect the observer should be used. Can you give me example in pseudocode please?

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• Question about a possible design pattern...

  - by Aftershock

  I have such a design in my mind.... My aim is to reuse the program with some features included and without some features. What is it called in the literature? class feature1 { void feature1function1(); void feature1function2(); } class feature2 { void feature2function1(); void feature2function2(); } class program: feature1, feature2 { void function1() { feature2function1(); } void function2() { feature1function1(); feature2function1(); } void execute() { function1(); function2(); } }

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• Is it a good practice to perform direct database access in the code-behind of an ASP.NET page?

  - by patricks418

  Hi, I am an experienced developer but I am new to web application development. Now I am in charge of developing a new web application and I could really use some input from experienced web developers out there. I'd like to understand exactly what experienced web developers do in the code-behind pages. At first I thought it was best to have a rule that all the database access and business logic should be performed in classes external to the code-behind pages. My thought was that only logic necessary for the web form would be performed in the code-behind. I still think that all the business logic should be performed in other classes but I'm beginning to think it would be alright if the code-behind had access to the database to query it directly rather than having to call other classes to receive a dataset or collection back. Any input would be appreciated.

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• Doubleton Pattern Implementation

  - by Pierreten

  I'm leveraging the Doubleton Pattern from this link http://www.codeproject.com/KB/architecture/designpattern_doubleton.aspx in my own code. I think it makes things a lot easier since the Singleton only provides one instance, but I get two with this pattern. I was wondering if it would make sense to have it implement an interface so I can inject it into my domain layer.

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• MySQL indexes - what are the best practises?

  - by Haroldo

  I've been using indexes on my mysql databases for a while now but never properly learnt about them. Generally I put an index on any fields that i will be searching or selecting using a WHERE clause but sometimes it doesn't seem so black and white. What are the best practises for mysql indexes? example situations/dilemas: If a table has six columns and all of them are searchable, should i index all of them or none of them? . What are the negetive performance impacts of indexing? . If i have a VARCHAR 2500 column which is searchable from parts of my site, should i index it?

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• Asynchronous SQL Operations

  - by Paul Hatcherian

  I've got a problem I'm not sure how best to solve. I have an application which updates a database in response to ad hoc requests. One request in particular is quite common. The request is an update that by itself is quite simple, but has some complex preconditions. For this request the business layer first requests a set of data from the data layer. The business logic layer evaluated the data from the database and parameters from the request, from this the action to be performed is determined, and the request's response message(s) are created. The business layer now executes the actual update command that is the purpose of the request. This last step is the problem, this command is dependent on the state of the database, which might have changed since the business logic ran. Locking down the data read in this operation across several round-trips to the database doesn't seem like a good idea either. Is there a 'best-practice' way to accomplish something like this? Thanks!

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• Which pattern to use for logging? Dependency Injection or Service Locator?

  - by andlju

  Consider this scenario. I have some business logic that now and then will be required to write to a log. interface ILogger { void Log(string stuff); } interface IDependency { string GetInfo(); } class MyBusinessObject { private IDependency _dependency; public MyBusinessObject(IDependency dependency) { _dependency = dependency; } public string DoSomething(string input) { // Process input var info = _dependency.GetInfo(); var intermediateResult = PerformInterestingStuff(input, info); if (intermediateResult== "SomethingWeNeedToLog") { // How do I get to the ILogger-interface? } var result = PerformSomethingElse(intermediateResult); return result; } } How would you get the ILogger interface? I see two main possibilities; Pass it using Dependency Injection on the constructor. Get it via a singleton Service Locator. Which method would you prefer, and why? Or is there an even better pattern? Update: Note that I don't need to log ALL method calls. I only want to log a few (rare) events that may or may not occur within my method.

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• Why doesn't String's hashCode() cache 0?

  - by polygenelubricants

  I noticed in the Java 6 source code for String that hashCode only caches values other than 0. The difference in performance is exhibited by the following snippet: public class Main{ static void test(String s) { long start = System.currentTimeMillis(); for (int i = 0; i < 10000000; i++) { s.hashCode(); } System.out.format("Took %d ms.%n", System.currentTimeMillis() - start); } public static void main(String[] args) { String z = "Allocator redistricts; strict allocator redistricts strictly."; test(z); test(z.toUpperCase()); } } Running this in ideone.com gives the following output: Took 1470 ms. Took 58 ms. So my questions are: Why doesn't String's hashCode() cache 0? What is the probability that a Java string hashes to 0? What's the best way to avoid the performance penalty of recomputing the hash value every time for strings that hash to 0? Is this the best-practice way of caching values? (i.e. cache all except one?) For your amusement, each line here is a string that hash to 0: pollinating sandboxes amusement & hemophilias schoolworks = perversive electrolysissweeteners.net constitutionalunstableness.net grinnerslaphappier.org BLEACHINGFEMININELY.NET WWW.BUMRACEGOERS.ORG WWW.RACCOONPRUDENTIALS.NET Microcomputers: the unredeemed lollipop... Incentively, my dear, I don't tessellate a derangement. A person who never yodelled an apology, never preened vocalizing transsexuals.

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• How are partial methods used in C# 3.0?

  - by Eric Z Beard

  I have read about partial methods in the latest C# language specification, so I understand the principles, but I'm wondering how people are actually using them. Is there a particular design pattern that benefits from partial methods?

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• One class per file rule in .NET?

  - by Joan Venge

  I follow this rule but some of my colleagues disagree with it and argue that if a class is smaller it can be left in the same file with other class(es). Another argument I hear all the time is "Even Microsoft don't do this, so why should we?" What's the general consensus on this? Are there cases where this should be avoided?

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• How to provide global functionality in multi-user database app

  - by Mike B

  I have been building a multi-user database application (in C#/WPF 4.0) that manages tasks for all employees of a company. I now need to add some functionality such as sending an email reminder to someone when a critical task is due. How should this be done? Obviously I don’t want every instance of the program to be performing this function (Heh each user would get 10+ emails). Should I add the capability to the application as a "Mode" and then run a copy on the database server in this mode or would it be better to create a new app altogether to perform "Global" type tasks? Is there a better way?

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• Why cast null before checking if object is equal to null?

  - by jacerhea

  I was looking through the "Domain Oriented N-Layered .NET 4.0 Sample App" project and ran across some code that I do not understand. In this project they often use syntax like the following to check arguments for null: public GenericRepository(IQueryableContext context,ITraceManager traceManager) { if (context == (IQueryableContext)null) throw new ArgumentNullException("context", Resources.Messages.exception_ContainerCannotBeNull); Why would you cast null to the type of the object you are checking for null?

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