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• Is there any difference between these two "if" conditional statement?

  - by Pandiya Chendur

  First if condition if(Txt1.Text != "" && Txt2.Text != "") Second if condition if((Txt1.Text && Txt2.Text) != "") Is there any diff between these two conditional statement?

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• Right design to validate attributes of a class instance

  - by systempuntoout

  Having a simple Python class like this: class Spam(object): __init__(self, description, value): self.description = description self.value = value Which is the correct approach to check these constraints: "description cannot be empty" "value must be greater than zero" Should i: 1.validate data before creating spam object ? 2.check data on __init__ method ? 3.create an is_valid method on Spam class and call it with spam.isValid() ? 4.create an is_valid static method on Spam class and call it with Spam.isValid(description, value) ? 5.check data on setters? 6.... Could you recommend a well designed\Pythonic\not verbose (on class with many attributes)\elegant approach?

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• Simplest way to create a wrapper class around some strings for a WPF DataGrid?

  - by Joel

  I'm building a simple hex editor in C#, and I've decided to use each cell in a DataGrid to display a byte*. I know that DataGrid will take a list and display each object in the list as a row, and each of that object's properties as columns. I want to display rows of 16 bytes each, which will require a wrapper with 16 string properties. While doable, it's not the most elegant solution. Is there an easier way? I've already tried creating a wrapper around a public string array of size 16, but that doesn't seem to work. Thanks *The rational for this is that I can have spaces between each byte without having to strip them all out when I want to save my edited file. Also it seems like it'll be easier to label the rows and columns.

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• Securing input of private / protected methods?

  - by ts

  Hello, normally, all sane developers are trying to secure input of all public methods (casting to proper types, validating, sanitizing etc.) My question is: are you in your code validating also parameters passed to protected / private methods? In my opinion it is not necessary, if you securize properly parameters of public methods and return values from outside (other classes, db, user input etc...). But I am constantly facing frameworks and apps (ie. prestashop to name one) where validation is often repeated in method call, in method body and once again for securize returned value - which, I think, is creating performace overhead and is also a sign of bad design.

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• PHP explode and set to empty string the missing pieces

  - by Marco Demaio

  What's the best way to accomplish the following. I have strings in this format: $s1 = "name1|type1"; //(pipe is the separator) $s2 = "name2|type2"; $s3 = "name3"; //(in some of them type can be missing) Let's assume namen/typen are strings and they can not contain a pipe. Since I need to exctract the name/type separetly, I do: $temp = explode($s1, '|'); $name = $temp[0]; $type = ( isset($temp[1]) ? $temp[1] : '' ); Is there an easier (smarter whatever faster) way to do this without having to do isset($temp[1]) or count($temp). Thanks!

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• When NOT to use MVVM?

  - by Vitalij

  I have started using MVVM pattern recently. I have had several projects where I used it and with every new one, I start to see that it will fit great within that new project. And now I start to ask myself are there situation when it's better NOT to use MVVM. Or is it such a nice pattern which you can use anywhere? Could you please describe several scenarios where MVVM wouldn't be the best choice?

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• When is C++ covariance the best solution?

  - by Neil Butterworth

  This question was asked here a few hours ago and made me realise that I have never actually used covariant return types in my own code. For those not sure what covariance is, it's allowing the return type of (typically) virtual functions to differ provided the types are part of the same inheritance hierarchy. For example: struct A { virtual ~A(); virtual A * f(); ... }; struct B : public A { virtual B * f(); ... }; The different return types of the two f() functions are said to be covariant. Older versions of C++ required the return types to be the same, so B would have to look like: struct B : public A { virtual A * f(); ... }; So, my question: Does anyone have a real-world example where covariant return types of virtual functions are required, or produce a superior solution to simply returning a base pointer or reference?

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• Help me to find a better approach-Design Pattern

  - by DJay

  I am working on an ASP.Net web application in which several WCF services are being used. At client level, I am creating channel factory mechanism to invoke service operations. Right now, I have created an assembly having classes used for channel factory creation code for every service. As per my assumption this is some sort of facade pattern. Please help me to find a better approach or any design pattern, which I can use here.

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• Which user account to assign as owner when attaching an SQL Server database?

  - by FreshCode

  This is a simple database security & performance question, but I've always used either a special user (eg. mydbuser), or Windows' built-in NETWORK SECURITY account as the owner when attaching databases to my SQL Server instances. When deploying my database to a production server, is there a specific user I should stick to or avoid? I would think that using an account with a set password could open the database up to a potential security issue.

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• Is it good practice to initialize array in C/C++?

  - by sand

  I recently encountered a case where I need to compare two files (golden and expected) for verification of test results and even though the data written to both the files were same, the files does not match. On further investigation, I found that there is a structure which contains some integers and a char array of 64 bytes, and not all the bytes of char array were getting used in most of the cases and unused fields from the array contain random data and that was causing the mismatch. This brought me ask the question whether it is good practice to initialize the array in C/C++ as well, as it is done in Java?

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• Which options do I have for Java process communication?

  - by Dmitriy Matveev

  We have a place in a code of such form: void processParam(Object param) { wrapperForComplexNativeObject result = jniCallWhichMayCrash(param); processResult(result); } processParam - method which is called with many different arguments. jniCallWhichMayCrash - a native method which is intended to do some complex processing of it's parameter and to create some complex object. It can crash in some cases. wrapperForComplexNativeObject - wrapper type generated by SWIG processResult - a method written in pure Java which processes it's parameter by creation of several kinds (by the kinds I'm not meaning classes, maybe some like hierarchies) of objects: 1 - Some non-unique objects which are referencing each other (from the same hierarchy), these objects can have duplicates created from the invocations of processParam() method with different parameter values. Since it's costly to keep all the duplicates it's necessary to cache them. 2 - Some unique objects which are referencing each other (from the same hierarchy) and some of the objects of 1st kind. After processParam is executed for each of the arguments from some set the data created in processResult will be processed together. The problem is in fact that jniCallWhichMayCrash method may crash the entire JVM and this will be very bad. The reason of crash may be such that it can happen for one argument value and not for the other. We've decided that it's better to ignore crashes inside of JVM and just skip some chunks of data when such crashes occur. In order to do this we should run processParam function inside of separate process and pass the result somehow (HOW? HOW?! This is a question) to the main process and in case of any crashes we will only lose some part of data (It's ok) without lose of everything else. So for now the main problem is implementation of transport between different processes. Which options do I have? I can think about serialization and transmitting of binary data by the streams, but serialization may be not very fast due to object complexity. Maybe I have some other options of implementing this?

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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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• database design - empty fields

  - by imanc

  Hey, I am currently debating an issue with a guy on my dev team. He believes that empty fields are bad news. For instance, if we have a customer details table that stores data for customers from different countries, and each country has a slightly different address configuration - plus 1-2 extra fields, e.g. French customer details may also store details for entry code, and floor/level plus title fields (madamme, etc.). South Africa would have a security number. And so on. Given that we're talking about minor variances my idea is to put all of the fields into the table and use what is needed on each form. My colleague believes we should have a separate table with extra data. E.g. customer_info_fr. But this seams to totally defeat the purpose of a combined table in the first place. His argument is that empty fields / columns is bad - but I'm struggling to find justification in terms of database design principles for or against this argument and preferred solutions. Another option is a separate mini EAV table that stores extra data with parent_id, key, val fields. Or to serialise extra data into an extra_data column in the main customer_data table. I think I am confused because what I'm discussing is not covered by 3NF which is what I would typically use as a reference for how to structure data. So my question specifically: - if you have slight variances in data for each record (1-2 different fields for instance) what is the best way to proceed?

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• Are there any inherent benefits or drawbacks to choosing Google Code vs. SourceForge vs. Codeplex?

  - by kdmurray

  I've got a couple of different projects that I'd like to post up as open source. I've been trying to decide which of the three big open-source project hosting sites makes the most sense, or if I should just host it myself. Are there any inherent drawbacks or benefits to these three? Is there a "best" place to host a project? Do different sites make more sense for different kinds of projects?

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• Are ASCII diagrams worth my time?

  - by Jesse Stimpson

  Are ASCII diagrams within source code worth the time they take to create? I could create a bitmap diagram much faster, but images are much more difficult to in line in a source file (until VS2010). For the record, I'm not talking about decorative ASCII art. Here's an example of a diagram I recently created for my code that I probably could have constructed in half the time in MS Paint. Scenario A: v (U)_________________(N)_______<--(P) Legend: ' / | J = ... ' / | P = ... ' /d | U = ... ' / | v = ... ' / | d = ... '/ | N = ... (J) | | | |___________________|

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• Documentation style: how do you differentiate variable names from the rest of the text within a comm

  - by Alix

  Hi, This is a quite superfluous and uninteresting question, I'm afraid, but I always wonder about this. When you're commenting code with inline comments (as opposed to comments that will appear in the generated documentation) and the name of a variable appears in the comment, how do you differentiate it from normal text? E.g.: // Try to parse type. parsedType = tryParse(type); In the comment, "type" is the name of the variable. Do you mark it in any way to signify that it's a symbol and not just part of the comment's text? I've seen things like this: // Try to parse "type". // Try to parse 'type'. // Try to parse *type*. // Try to parse <type>. // Try to parse [type]. And also: // Try to parse variable type. (I don't think the last one is very helpful; it's a bit confusing; you could think "variable" is an adjective there) Do you have any preference? I find that I need to use some kind of marker; otherwise the comments are sometimes ambiguous, or at least force you to reread them when you realise a particular word in the comment was actually the name of a variable. (In comments that will appear in the documentation I use the appropriate tags for the generator, of course: @code, <code></code>, etc) Thanks!

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• Why use singleton instead of static class?

  - by Jouke van der Maas

  When would a singleton actually be easier or better than a static class? It seems to me creating a singleton is just extra effort that's not actually needed, but I'm sure there is a good reason. Otherwise, they wouldn't be used, obviously.

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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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• Where do I put the Current user query so as to not repeat per controller?

  - by Kevin

  I have a standard query that gets the current user object: @user = User.find_by_email(session[:email]) but I'm putting it as the first line in every single controller action which is obviously not the best way to do this. What is the best way to refactor this? Do I put this as a method in the Application controller (and if so, can you just show me a quick example)? Do I put the entire @user object into the session (has about 50 columns and some sensitive ones like is_admin)? Or is there another way to remove this kind of redundancy?

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• Beginner Design pattern question (Web Services involved)

  - by zombie

  Hi all ! I am a noob to web services world. I need to develop a login validator module and expose it as a service. I want it to be service independent, i.e I should have the option of exposing it as a SOAP service or REST service in the future. What pattern should I follow ? Sorry if I am unclear in my requirements, I can clarify as per need. Thanks !! Edit : I am using Eclipse as an IDE and Jersey libraries. I am not into any framework, simply using the MVC pattern. I find a lot of difference between SOAP ann REST methods, so I want my methods to be implementation independent - i.e I should be easily able to use my method through a SOAP or REST service call as per need. What should I do for maximum flexibility ?

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• Elegant and 'correct' multiton implementation in Objective C?

  - by submachine

  Would you call this implementation of a multiton in objective-c 'elegant'? I have programmatically 'disallowed' use of alloc and allocWithZone: because the decision to allocate or not allocate memory needs to be done based on a key. I know for sure that I need to work with only two instances, so I'm using 'switch-case' instead of a map. #import "Multiton.h" static Multiton *firstInstance = nil; static Multiton *secondInstance = nil; @implementation Multiton + (Multiton *) sharedInstanceForDirection:(char)direction { return [[self allocWithKey:direction] init]; } + (id) allocWithKey:(char)key { return [self allocWithZone:nil andKey:key]; } + (id)allocWithZone:(NSZone *)zone andKey:(char)key { Multiton **sharedInstance; @synchronized(self) { switch (key) { case KEY_1: sharedInstance = &firstInstance; break; case KEY_2: sharedInstance = &secondInstance; break; default: [NSException raise:NSInvalidArgumentException format:@"Invalid key"]; break; } if (*sharedInstance == nil) *sharedInstance = [super allocWithZone:zone]; } return *sharedInstance; } + (id) allocWithZone:(NSZone *)zone { //Do not allow use of alloc and allocWithZone [NSException raise:NSObjectInaccessibleException format:@"Use allocWithZone:andKey: or allocWithKey:"]; return nil; } - (id) copyWithZone:(NSZone *)zone { return self; } - (id) retain { return self; } - (unsigned) retainCount { return NSUIntegerMax; } - (void) release { return; } - (id) autorelease { return self; } - (id) init { [super init]; return self; } PS: I've not tried out if this works as yet, but its compiling cleanly :)

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• How can I use Object Oriented Javascript to interact with HTML Objects

  - by Steve

  I am very new to object orientated javascript, with experience writing gui's in python and java. I am trying to create html tables that I can place in locations throughout a webpage. Each html table would have two css layouts that control if it is selected or not. I can write all of the interaction if I only have one table. It gets confusing when I have multiple tables. I am wondering how to place these tables throughout a blank webpage and then access the tables individually. I think I am having trouble understanding how inheritance and hierarchy works in javascript/html. NOTE: I am not asking how to make a table. I am trying to dynamically create multiple tables and place them throughout a webpage. Then access their css independently and change it (move them to different locations or change the way the look, independently of the other tables).

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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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• Programmatically using tab character in .NET?

  - by Joan Venge

  Is there a way to use a tab character like a new line character inside Environment class, instead of using "\t"?

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• What elegant method callback design should be used ?

  - by ereOn

  Hi, I'm surprised this question wasn't asked before on SO (well, at least I couldn't find it). Have you ever designed a method-callback pattern (something like a "pointer" to a class method) in C++ and, if so, how did you do it ? I know a method is just a regular function with some hidden this parameter to serve as a context and I have a pretty simple design in mind. However, since things are often more complex than they seem to, I wonder how our C++ gurus would implement this, preferably in an elegant and standard way. All suggestions are welcome !

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