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• Benefits of classic OOP over Go-like language

  - by tylerl

  I've been thinking a lot about language design and what elements would be necessary for an "ideal" programming language, and studying Google's Go has led me to question a lot of otherwise common knowledge. Specifically, Go seems to have all of the interesting benefits from object oriented programming without actually having any of the structure of an object oriented language. There are no classes, only structures; there is no class/structure inheritance -- only structure embedding. There aren't any hierarchies, no parent classes, no explicit interface implementations. Instead, type casting rules are based on a loose system similar to duck-typing, such that if a struct implements the necessary elements of a "Reader" or a "Request" or an "Encoding", then you can cast it and use it as one. Does such a system obsolete the concept of OOP? Or is there something about OOP as implemented in C++ and Java and C# that is inherently more capable, more maintainable, somehow more powerful that you have to give up when moving to a language like Go? What benefit do you have to give up to gain the simplicity that this new paradigm represents?

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• An ideal way to decode JSON documents in C?

  - by AzizAG

  Assuming I have an API to consume that uses JSON as a data transmission method, what is an ideal way to decode the JSON returned by each API resource? For example, in Java I'd create a class for each API resource then initiate an object of that class and consume data from it. for example: class UserJson extends JsonParser { public function UserJson(String document) { /*Initial document parsing goes here...*/ } //A bunch of getter methods . . . . } The probably do something like this: UserJson userJson = new UserJson(jsonString);//Initial parsing goes in the constructor String username = userJson.getName();//Parse JSON name property then return it as a String. Or when using a programming language with associative arrays(i.e., hash table) the decoding process doesn't require creating a class: (PHP) $userJson = json_decode($jsonString);//Decode JSON as key=>value $username = $userJson['name']; But, when I'm programming in procedural programming languages (C), I can't go with either method, since C is neither OOP nor supports associative arrays(by default, at least). What is the "correct" method of parsing pre-defined JSON strings(i.e., JSON documents specified by the API provider via examples or documentation)? The method I'm currently using is creating a file for each API resource to parse, the problem with this method is that it's basically a lousy version of the OOP method, as it looks exactly like the OOP method but doesn't provide any OOP benefits(e.g., can't pass an object of the parser, etc.). I've been thinking about encapsulating each API resource parser file in a publicly accessed structure(pointing all functions/publicly usable variables to the structure) then accessing the parser file code from within the structure(parser.parse(), parser.getName(), etc.). As this way looks a bit better than the my current method, it still just a rip off the OOP way, isn't it? Any suggestions for methods to parse JSON documents on procedural programming lanauges? Any comments on the methods I'm currently using(either 3 of them)?

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• Mocking concrete class - Not recommended

  - by Mik378

  I've just read an excerpt of "Growing Object-Oriented Software" book which explains some reasons why mocking concrete class is not recommended. Here some sample code of a unit-test for the MusicCentre class: public class MusicCentreTest { @Test public void startsCdPlayerAtTimeRequested() { final MutableTime scheduledTime = new MutableTime(); CdPlayer player = new CdPlayer() { @Override public void scheduleToStartAt(Time startTime) { scheduledTime.set(startTime); } } MusicCentre centre = new MusicCentre(player); centre.startMediaAt(LATER); assertEquals(LATER, scheduledTime.get()); } } And his first explanation: The problem with this approach is that it leaves the relationship between the objects implicit. I hope we've made clear by now that the intention of Test-Driven Development with Mock Objects is to discover relationships between objects. If I subclass, there's nothing in the domain code to make such a relationship visible, just methods on an object. This makes it harder to see if the service that supports this relationship might be relevant elsewhere and I'll have to do the analysis again next time I work with the class. I can't figure out exactly what he means when he says: This makes it harder to see if the service that supports this relationship might be relevant elsewhere and I'll have to do the analysis again next time I work with the class. I understand that the service corresponds to MusicCentre's method called startMediaAt. What does he mean by "elsewhere"? The complete excerpt is here: http://www.mockobjects.com/2007/04/test-smell-mocking-concrete-classes.html

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• Composing programs from small simple pieces: OOP vs Functional Programming

  - by Jay Godse

  I started programming when imperative programming languages such as C were virtually the only game in town for paid gigs. I'm not a computer scientist by training so I was only exposed to Assembler and Pascal in school, and not Lisp or Prolog. Over the 1990s, Object-Oriented Programming (OOP) became more popular because one of the marketing memes for OOP was that complex programs could be composed of loosely coupled but well-defined, well-tested, cohesive, and reusable classes and objects. And in many cases that is quite true. Once I learned object-oriented programming my C programs became better because I structured them more like classes and objects. In the last few years (2008-2014) I have programmed in Ruby, an OOP language. However, Ruby has many functional programming (FP) features such as lambdas and procs, which enable a different style of programming using recursion, currying, lazy evaluation and the like. (Through ignorance I am at a loss to explain why these techniques are so great). Very recently, I have written code to use methods from the Ruby Enumerable library, such as map(), reduce(), and select(). Apparently this is a functional style of programming. I have found that using these methods significantly reduce code volume, and make my code easier to debug. Upon reading more about FP, one of the marketing claims made by advocates is that FP enables developers to compose programs out of small well-defined, well-tested, and reusable functions, which leads to less buggy code, and low code volume. QUESTIONS: Is the composition of complex program by using FP techniques contradictory to or complementary to composition of a complex program by using OOP techniques? In which situations is OOP more effective, and when is FP more effective? Is it possible to use both techniques in the same complex program? Do the techniques overlap or contradict each other?

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• Data classes: getters and setters or different method design

  - by Frog

  I've been trying to design an interface for a data class I'm writing. This class stores styles for characters, for example whether the character is bold, italic or underlined. But also the font-size and the font-family. So it has different types of member variables. The easiest way to implement this would be to add getters and setters for every member variable, but this just feels wrong to me. It feels way more logical (and more OOP) to call style.format(BOLD, true) instead of style.setBold(true). So to use logical methods insteads of getters/setters. But I am facing two problems while implementing these methods: I would need a big switch statement with all member variables, since you can't access a variable by the contents of a string in C++. Moreover, you can't overload by return type, which means you can't write one getter like style.getFormatting(BOLD) (I know there are some tricks to do this, but these don't allow for parameters, which I would obviously need). However, if I would implement getters and setters, there are also issues. I would have to duplicate quite some code because styles can also have a parent styles, which means the getters have to look not only at the member variables of this style, but also at the variables of the parent styles. Because I wasn't able to figure out how to do this, I decided to ask a question a couple of weeks ago. See Object Oriented Programming: getters/setters or logical names. But in that question I didn't stress it would be just a data object and that I'm not making a text rendering engine, which was the reason one of the people that answered suggested I ask another question while making that clear (because his solution, the decorator pattern, isn't suitable for my problem). So please note that I'm not creating my own text rendering engine, I just use these classes to store data. Because I still haven't been able to find a solution to this problem I'd like to ask this question again: how would you design a styles class like this? And why would you do that? Thanks on forehand!

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• How to REALLY start thinking in terms of objects?

  - by Mr Grieves

  I work with a team of developers who all have several years of experience with languages such as C# and Java. Most of them are young enough to have been shown OOP as a standard way to develop software in university and are very comfortable with concepts such as inheritance, abstraction, encapsulation and polymorphism. Yet, many of them, and I have to include myself, still tend to create classes which are meant to be used in a very functional fashion. The resulting software is often several smaller classes which correctly represent business objects which get passed through larger classes which only supply ways to modify and use those objects (functions). Large complex difficult-to-maintain classes named Manager are usually the result of such behaviour. I can see two theoretical reasons why people might write this type of code: It's easy to start thinking of everything in terms of the database Deep down, for me, a computer handling a web request feels more like a functional operation than an object oriented operation when you think about Request Handlers, Threads, Processes, CPU Cores and CPU operations... I want source code which is easy to read and easy to modify. I have seen excellent examples of OO code which meet these objectives. How can I start writing code like this? How I can I really start thinking in an object oriented fashion? How can I share such a mentality with my colleagues?

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• How to implement isValid correctly?

  - by Songo

  I'm trying to provide a mechanism for validating my object like this: class SomeObject { private $_inputString; private $_errors=array(); public function __construct($inputString) { $this->_inputString = $inputString; } public function getErrors() { return $this->_errors; } public function isValid() { $isValid = preg_match("/Some regular expression here/", $this->_inputString); if($isValid==0){ $this->_errors[]= 'Error was found in the input'; } return $isValid==1; } } Then when I'm testing my code I'm doing it like this: $obj = new SomeObject('an INVALID input string'); $isValid = $obj->isValid(); $errors=$obj->getErrors(); $this->assertFalse($isValid); $this->assertNotEmpty($errors); Now the test passes correctly, but I noticed a design problem here. What if the user called $obj->getErrors() before calling $obj->isValid()? The test will fail because the user has to validate the object first before checking the error resulting from validation. I think this way the user depends on a sequence of action to work properly which I think is a bad thing because it exposes the internal behaviour of the class. How do I solve this problem? Should I tell the user explicitly to validate first? Where do I mention that? Should I change the way I validate? Is there a better solution for this? UPDATE: I'm still developing the class so changes are easy and renaming functions and refactoring them is possible.

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• How to model an address type in DDD?

  - by Songo

  I have an User entity that has a Set of Address where Address is a value object: class User{ ... private Set<Address> addresses; ... public setAddresses(Set<Address> addresses){ //set all addresses as a batch } ... } A User can have a home address and a work address, so I should have something that acts as a look up in the database: tbl_address_type ------------------------------------------------ | address_type_id | address_type | ------------------------------------------------ | 1 | work | ------------------------------------------------ | 2 | home | ------------------------------------------------ and correspondingly tbl_address ------------------------------------------------------------------------------------- | address_id | address_description |address_type_id| user_id | ------------------------------------------------------------------------------------- | 1 | 123 main street | 1 | 100 | ------------------------------------------------------------------------------------- | 2 | 456 another street | 1 | 100 | ------------------------------------------------------------------------------------- | 3 | 789 long street | 2 | 200 | ------------------------------------------------------------------------------------- | 4 | 023 short street | 2 | 200 | ------------------------------------------------------------------------------------- Should the address type be modeled as an Entity or Value type? and Why? Is it OK for the Address Value object to hold a reference to the Entity AdressType (in case it was modeled as an entity)? Is this something feasible using Hibernate/NHibernate? If a user can change his home address, should I expose a User.updateHomeAddress(Address homeAddress) function on the User entity itself? How can I enforce that the client passes a Home address and not a work address in this case? (a sample implementation is most welcomed) If I want to get the User's home address via User.getHomeAddress() function, must I load the whole addresses array then loop it and check each for its type till I found the correct type then return it? Is there a more efficient way than this?

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• What's faster? select [object] or select new {[object].value1, [object].value2} with linq

  - by Darcy

  I was hoping some of you guru's out there know the answer to this question. Which is faster? A or B A: var item = from d in database select d; B: var item = from d in database select new {d.item1, d.item2}; SEEMINGLY, it seems like selecting part of the table object would be faster than selecting the entire object, but something tells me its not necessarily the case.

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• SQL SERVER – SSMS: Top Object and Batch Execution Statistics Reports

  - by Pinal Dave

  The month of June till mid of July has been the fever of sports. First, it was Wimbledon Tennis and then the Soccer fever was all over. There is a huge number of fan followers and it is great to see the level at which people sometimes worship these sports. Being an Indian, I cannot forget to mention the India tour of England later part of July. Following these sports and as the events unfold to the finals, there are a number of ways the statisticians can slice and dice the numbers. Cue from soccer I can surely say there is a team performance against another team and then there is individual member fairs against a particular opponent. Such statistics give us a fair idea to how a team in the past or in the recent past has fared against each other, head-to-head stats during World cup and during other neutral venue games. All these statistics are just pointers. In reality, they don’t reflect the calibre of the current team because the individuals who performed in each of these games are totally different (Typical example being the Brazil Vs Germany semi-final match in FIFA 2014). So at times these numbers are misleading. It is worth investigating and get the next level information. Similar to these statistics, SQL Server Management studio is also equipped with a number of reports like a) Object Execution Statistics report and b) Batch Execution Statistics reports. As discussed in the example, the team scorecard is like the Batch Execution statistics and individual stats is like Object Level statistics. The analogy can be taken only this far, trust me there is no correlation between SQL Server functioning and playing sports – It is like I think about diet all the time except while I am eating. Performance – Batch Execution Statistics Let us view the first report which can be invoked from Server Node -> Reports -> Standard Reports -> Performance – Batch Execution Statistics. Most of the values that are displayed in this report come from the DMVs sys.dm_exec_query_stats and sys.dm_exec_sql_text(sql_handle). This report contains 3 distinctive sections as outline below.   Section 1: This is a graphical bar graph representation of Average CPU Time, Average Logical reads and Average Logical Writes for individual batches. The Batch numbers are indicative and the details of individual batch is available in section 3 (detailed below). Section 2: This represents a Pie chart of all the batches by Total CPU Time (%) and Total Logical IO (%) by batches. This graphical representation tells us which batch consumed the highest CPU and IO since the server started, provided plan is available in the cache. Section 3: This is the section where we can find the SQL statements associated with each of the batch Numbers. This also gives us the details of Average CPU / Average Logical Reads and Average Logical Writes in the system for the given batch with object details. Expanding the rows, I will also get the # Executions and # Plans Generated for each of the queries. Performance – Object Execution Statistics The second report worth a look is Object Execution statistics. This is a similar report as the previous but turned on its head by SQL Server Objects. The report has 3 areas to look as above. Section 1 gives the Average CPU, Average IO bar charts for specific objects. The section 2 is a graphical representation of Total CPU by objects and Total Logical IO by objects. The final section details the various objects in detail with the Avg. CPU, IO and other details which are self-explanatory. At a high-level both the reports are based on queries on two DMVs (sys.dm_exec_query_stats and sys.dm_exec_sql_text) and it builds values based on calculations using columns in them: SELECT * FROM    sys.dm_exec_query_stats s1 CROSS APPLY sys.dm_exec_sql_text(sql_handle) AS s2 WHERE   s2.objectid IS NOT NULL AND DB_NAME(s2.dbid) IS NOT NULL ORDER BY  s1.sql_handle; This is one of the simplest form of reports and in future blogs we will look at more complex reports. I truly hope that these reports can give DBAs and developers a hint about what is the possible performance tuning area. As a closing point I must emphasize that all above reports pick up data from the plan cache. If a particular query has consumed a lot of resources earlier, but plan is not available in the cache, none of the above reports would show that bad query. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL Tagged: SQL Reports

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• SqlLite/Fluent NHibernate integration test harness initialization not repeatable after large data se

  - by Mark Rogers

  In one of my main data integration test harnesses I create and use Fluent NHibernate's SingleConnectionSessionSourceForSQLiteInMemoryTesting, to get a fresh session for each test. After each test, I close the connection, session, and session factory, and throw out the nested StructureMap container they came from. This works for almost any simple data integration test I can think, including ones that utilize Fluent NHib's PersistenceSpecification object. When I test the application's lengthy database bootstrapping process, which creates and saves thousands of domain objects, I start seeing issues. It's not that the setup and tear down fails, in fact, the test successfully bootstraps the in-memory database as the application would bootstrap the real database in the production environment. The problem occurs when the database bootstrapping occurs a second time on a new in-memory database, with a new session and session factory. The error is: NHibernate.StaleStateException : Unexpected row count: 0; expected: 1 The row count is indeed Unexpected, the row that the application under test is looking for should be in the session. You see, it's not that any data from the last integration test is sticking around, it's that for some reason the session just stops working mid-database-boostrap. And I've looked everywhere for a place I might be holding on to an old session and I can't find one. I've searched through the code for static singleton objects, but there are none anywhere near the code in question. I have a couple StructureMap InstanceScope singleton's but they are getting thrown out with each nested container that is lost after every test teardown. I've tried every possible variation on disposing and closing every object involved with each test teardown and it still fails on this lengthy database bootstrap. But non-bootstrap related database tests appear to work fine. I'm starting to run out of options and may have to surrender lengthy database integration tests in favor of WatiN-based acceptance tests. Can anyone give me any clue about how I can figure out why some of my SingleConnectionSessionSourceForSQLiteInMemoryTesting aren't repeatable? Any advice at all, about how to make an NHibernate SqlLite database integration test harness repeatable?

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• log4js ConsoleAppender initialization

  - by perrierism

  I'm wondering if anyone happens to have some experience using Log4js? It seems its normal ConsoleAppender isn't always ready to use immediately after it's added to a logger object... If I have two sequential script tags in a document like: //Initialize logger <script type="text/javascript"> var logger = new Log4js.getLogger("JSLOG"); logger.addAppender(new Log4js.ConsoleAppender(logger, false)); logger.setLevel(Log4js.Level.INFO); </script> //Use logger <script type="text/javascript"> logger.info('Test test'); </script> ... It causes the console pop-up (pop-up window) to appear with an error message on page load: 12:58:23 PM WARN Log4js - Could not run the listener function () { return fn.apply(object, arguments); }. TypeError: this.outputElement is null The console is still initialised, it's there afterward, but for just that first logger call it doesn't seem to be there fully. If I make the first logger call setTimeout("logger.info('test test')", 1000), it doesn't have the error. So it's like it's not ready immediately. Anyone see this before or know what a workaround might be? Cheers

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• What does 'postMessage()' do when called on an object tag?

  - by Stephano

  I was recently searching for a way to call the print function on a PDF I was displaying in adobe air. I solved this problem with a little help from this fellow, and by calling postMessage on my PDF like so: //this is the HTML I use to view my PDF <object id="PDFObj" data="test.pdf" type="application/pdf"/> ... //this actionscript lives in my air app var pdfObj:Object = htmlLoader.window.document.getElementById("PDFObj"); pdfObj.postMessage([message]); I've tried this in JavaScript as well, just to be sure it wasn't adobe sneaking in and helping me out... var obj = document.getElementById("PDFObj"); obj.postMessage([message]); Works well in JavaScript and in ActionScript. I looked up what the MDC had to say about postMessage, but all I found was window.postMessage. Now, the code works like a charm, and postMessage magically sends my message to my PDF's embedded JavaScript. However, I'm still not sure how I'm doing this. Any ideas?

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• Trouble with object injection in Spring.Net

  - by Abdel Olakara

  Hi all, I have a issue with my Spring.Net configuration where its not injecting an object. I have a CommService to which an object named GeneralEmail is injected to. Here is the configuration: <!-- GeneralMail Object --> <object id="GeneralMailObject" type="CommUtil.Email.GeneralEmail, CommUtil"> <constructor-arg name="host" value="xxxxx.com"/> <constructor-arg name="port" value="25"/> <constructor-arg name="user" value="[email protected]"/> <constructor-arg name="password" value="xxxxx"/> <constructor-arg name="template" value="xxxxx"/> </object> <!-- Communication Service --> <object id="CommServiceObject" type="TApp.Code.Services.CommService, TApp"> <property name="emailService" ref="GeneralMailObject" /> </object> The communication service object is again injected to many other aspx pages & service. In one scenario, I need to call the commnucation service from an static WebMethod. I try doing: CommService cso = new CommService(); But when i try to get the emailService object, its null! why didn't the spring inject the GeneralMail object into my cso object? What am I doing wrong and how do I access the object from spring container. Thanks in advance for the suggestions and solutions. Reagrds, Abdel Olakara

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• Pointer initialization

  - by SoulBeaver

  Sorry if this question has been asked before. On my search through SO I didn't find one that asked what I wanted to know. Basically, when I have this: typedef struct node { int data; node *node; } *head; and do node *newItem = new node; I am under the impression that I am declaring and reserving space, but not defining, a pointer to struct node, is that correct? So when I do newItem->data = 100 and newItem->next = 0 I get confused. newItem = 0would declare what exactly? Both data and next? The object as a whole? I'm especially confused when I use typedef. Which part is the macro? I assume node because that's how I call it, but why do I need it? Finally, what happens when I do: node *temp; temp = new node; temp = head->next; head->next = newItem; newItem->next = temp; I mean, head-next is a pointer pointing to object newItem, so I assume not to newItem.data or next themselves. So how can I use an uninitialized pointer that I described above safely like here? is head now not pointing to an uninitialized pointer?

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• For each <item> in CheckedListBox. <item> returns as Object and not as Control

  - by Tivie

  Hello there. I have a CheckedListBox previously populated. I want to loop with a "for each / next" through all items in the CheckedListBox and do a lot of "stuff" with each iteration element of the checkedlistbox. example code: For Each item In CheckedListBox1.Items If item.Checked = True Then 'do stuff like item.BackColor = Color.Blue Else 'do other stuff item.BackColor = Color.Brown End If Next the problem is that is an 'Object' type and not a 'Control' type. If I force the iteration var As CheckBox, it throws an InvalidCastException saying that type 'System.String' can't be associated with type 'System.Windows.Forms.CheckBox' I know I can easily work around using for i=0 to CheckedListBox.Items.Count - 1 but I want to use a for each /next loop since I have a lot of code in that loop (and With can't be used) and always poiting directly to the object is something I wish to avoid and I really need the code to be as simple as possible. I actually spent one afternoon looking for this but couldn't find any answer. If someone could be kind enough to enlight me in this, it would be extremely appreciated. Best regards

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• Google App Engine how to get an object from the servlet ?

  - by Frank

  I have the following class objects in Google App Engine's dadastore, I can see them from the "Datastore Viewer " : import javax.jdo.annotations.IdGeneratorStrategy; import javax.jdo.annotations.IdentityType; import javax.jdo.annotations.PersistenceCapable; import javax.jdo.annotations.Persistent; import javax.jdo.annotations.PrimaryKey; @PersistenceCapable(identityType=IdentityType.APPLICATION) public class Contact_Info_Entry implements Serializable { @PrimaryKey @Persistent(valueStrategy=IdGeneratorStrategy.IDENTITY) Long Id; public static final long serialVersionUID=26362862L; String Contact_Id="",First_Name="",Last_Name="",Company_Name="",Branch_Name="",Address_1="",Address_2="",City="",State="",Zip="",Country=""; double D_1,D_2; boolean B_1,B_2; Vector<String> A_Vector=new Vector<String>(); public Contact_Info_Entry() { } ...... } How can my java applications get the object from a servlet url ? For instance if have an instance of Contact_Info_Entry who's Contact_Id is "ABC-123", and my App Id is : nm-java When my java program accesses the url : "http://nm-java.appspot.com/Check_Contact_Info?Contact_Id=ABC-123 How will the Check_Contact_Info servlet get the object from datastore and return it to my app ? public class Check_Contact_Info_Servlet extends HttpServlet { static boolean Debug=true; public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException { } ... protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException { doGet(request,response); } } Frank

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• Why junit ComparisonFailure is not used by assertEquals(Object, Object) ?

  - by Philippe Blayo

  In Junit 4, do you see any drawback to throw a ComparisonFailure instead of an AssertionError when assertEquals(Object, Object) fails ? assertEquals(Object, Object) throws a ComparisonFailure if both expected and actual are String an AssertionError if either is not a String @Test(expected=ComparisonFailure.class ) public void twoString() { assertEquals("a String", "another String"); } @Test(expected=AssertionError.class ) public void oneString() { assertEquals("a String", new Object()); } The two reasons why I ask the question: ComparisonFailure provide far more readable way to spot the differences in dialog box of eclipse or Intellij IDEA (FEST-Assert throws this exception) Junit 4 already use String.valueOf(Object) to build message "expected ... but was ..." (format method invoqued by Assert.assertEquals(message, Object, Object) in junit-4.8.2): static String format(String message, Object expected, Object actual) { ... String expectedString= String.valueOf(expected); String actualString= String.valueOf(actual); if (expectedString.equals(actualString)) return formatted + "expected: " + formatClassAndValue(expected, expectedString) +" but was: " + formatClassAndValue(actual, actualString); else return formatted +"expected:<"+ expectedString +"> but was:<"+ actualString +">"; Isn't it possible in assertEquals(message, Object, Object) to replace fail(format(message, expected, actual)); by throw new ComparisonFailure(message, formatClassAndValue(expectedObject, expectedString), formatClassAndValue(actualObject, actualString)); Do you see any compatibility issue with other tool, any algorithmic problem with that... ?

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• Efficiency of Java "Double Brace Initialization"?

  - by Jim Ferrans

  In Hidden Features of Java the top answer mentions Double Brace Initialization, with a very enticing syntax: Set<String> flavors = new HashSet<String>() {{ add("vanilla"); add("strawberry"); add("chocolate"); add("butter pecan"); }}; This idiom creates an anonymous inner class with just an instance initializer in it, which "can use any [...] methods in the containing scope". Main question: Is this as inefficient as it sounds? Should its use be limited to one-off initializations? (And of course showing off!) Second question: The new HashSet must be the "this" used in the instance initializer ... can anyone shed light on the mechanism? Third question: Is this idiom too obscure to use in production code? Summary: Very, very nice answers, thanks everyone. On question (3), people felt the syntax should be clear (though I'd recommend an occasional comment, especially if your code will pass on to developers who may not be familiar with it). On question (1), The generated code should run quickly. The extra .class files do cause jar file clutter, and slow program startup slightly (thanks to coobird for measuring that). Thilo pointed out that garbage collection can be affected, and the memory cost for the extra loaded classes may be a factor in some cases. Question (2) turned out to be most interesting to me. If I understand the answers, what's happening in DBI is that the anonymous inner class extends the class of the object being constructed by the new operator, and hence has a "this" value referencing the instance being constructed. Very neat. Overall, DBI strikes me as something of an intellectual curiousity. Coobird and others point out you can achieve the same effect with Arrays.asList, varargs methods, Google Collections, and the proposed Java 7 Collection literals. Newer JVM languages like Scala, JRuby, and Groovy also offer concise notations for list construction, and interoperate well with Java. Given that DBI clutters up the classpath, slows down class loading a bit, and makes the code a tad more obscure, I'd probably shy away from it. However, I plan to spring this on a friend who's just gotten his SCJP and loves good natured jousts about Java semantics! ;-) Thanks everyone!

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• List<element> initialization fires "Process is terminated due to StackOverflowException"

  - by netmajor

  I have structs like below and when I do that initialization: ArrayList nodesMatrix = null; List<vertex> vertexMatrix = null; List<bool> odwiedzone = null; List<element> priorityQueue = null; vertexMatrix = new List<vertex>(nodesNr + 1); nodesMatrix = new ArrayList(nodesNr + 1); odwiedzone = new List<bool>(nodesNr + 1); priorityQueue = new List<element>(); arr.NodesMatrix = nodesMatrix; arr.VertexMatrix = vertexMatrix; arr.Odwiedzone = odwiedzone; arr.PriorityQueue = priorityQueue; //only here i have exception debuger fires Process is terminated due to StackOverflowException :/ Some idea why this collection fires this exception ? private struct arrays { ArrayList nodesMatrix; public ArrayList NodesMatrix { get { return nodesMatrix; } set { nodesMatrix = value; } } List<vertex> vertexMatrix; public List<vertex> VertexMatrix { get { return vertexMatrix; } set { vertexMatrix = value; } } List<bool> odwiedzone; public List<bool> Odwiedzone { get { return odwiedzone; } set { odwiedzone = value; } } public List<element> PriorityQueue { get { return PriorityQueue; } set { PriorityQueue = value; } } } public struct element : IComparable { public double priority { get { return priority; } set { priority = value; } } public int node { get { return node; } set { node = value; } } public element(double _prio, int _node) { priority = _prio; node = _node; } #region IComparable Members public int CompareTo(object obj) { element elem = (element)obj; return priority.CompareTo(elem.priority); } #endregion

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• Function-Local Static Const variable Initialization semantics.

  - by Hassan Syed

  The questions are in bold, for those that cannot be bothered reading a question in depth. This is a followup to this question. It is to do with the initialization semantics of static variables in functions. Static variables should be initialized once, and their internal state might be altered later - as I (currently) do in the linked question. However, the code in question does not require the feature to change the state of the variable later. Let me clarrify my position, since I don't require the string object's internal state to change. The code is for a trait class for meta programming, and as such would would benifit from a const char * const ptr -- thus Ideally a local cost static const variable is needed. My educated guess is that in this case the string in question will be optimally placed in memory by the link-loader, and that the code is more secure and maps to the intended semantics. This leads to the semantics of such a variable "The C++ Programming language Third Edition -- Stroustrup" does not have anything (that I could find) to say about this matter. All that is said is that the variable is initialized once when the flow of control of the thread first reaches the code. This leads me to ponder if the following code would be sensible, and if not what are the intended semantics ?. #include <iostream> const char * const GetString(const char * x_in) { static const char * const x = x_in; return x; } int main() { const char * const temp = GetString("yahoo"); std::cout << temp << std::endl; const char * const temp2 = GetString("yahoo2"); std::cout << temp2 << std::endl; } The following compiles on GCC and prints "yahoo" twice. Which is what I want -- However it might not be standards compliant (which is why I post this question). It might be more elegant to have two functions, "SetString" and "String" where the latter forwards to the first. If it is standards compliant does someone know of a templates implementation in boost (or elsewhere) ?

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• Dapper and object validation/business rules enforcement

  - by Eugene

  This isn't really Dapper-specific, actually, as it relates to any XML-serializeable object.. but it came up when I was storing an object using Dapper. Anyways, say I have a user class. Normally, I'd do something like this: class User { public string SIN {get; private set;} public string DisplayName {get;set;} public User(string sin) { if (string.IsNullOrWhiteSpace(sin)) throw new ArgumentException("SIN must be specified"); this.SIN = sin; } } Since a SIN is required, I'd just create a constructor with a sin parameter, and make it read-only. However, with a Dapper (and probably any other ORM), I need to provide a parameterless constructor, and make all properties writeable. So now I have this: class User: IValidatableObject { public int Id { get; set; } public string SIN { get; set; } public string DisplayName { get; set; } public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) { // implementation } } This seems.. can't really pick the word, a bad smell? A) I'm allowing to change properties that should not be changed ever after an object has been created (SIN, userid) B) Now I have to implement IValidatableObject or something like that to test those properties before updating them to db. So how do you go about it ?

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• Issue 55 - Skin Object Tokens, Optimized Control Panel, OWS Validation and Security, RAD

  April 2010 Welcome to Issue 55 of DNN Creative Magazine In this issue we focus on the new Skin Object token method introduced in DotNetNuke 5 for adding tokens into a DotNetNuke skin. A Skin Object Token is a web user control which covers skin elements such as the logo, menu, search, login links, date, copyright, languages, links, banners, privacy, terms of use, etc. Following this we demonstrate how to install and use two Advanced DotNetNuke Admin Control Panels which are available for free from Oliver Hine. These control panels provide an optimized version of the admin control panel to improve performance and page load times, as well as a ribbon bar control panel which adds additional features. Next, we continue the Open Web Studio tutorials, this month we demonstrate some very advanced techniques for building a car parts application in Open Web Studio. Throughout the tutorial we cover form input, validation, how to use dependant drop down lists, populating checkbox lists and introduce a new concept of data level security. Data level security allows you to control which data a user can access within a module. To finish, we have part five of the "How to Build a News Application with DotNetMushroom Rapid Application Developer (RAD)" article, where we demonstrate how to implement paging. This issue comes complete with 14 videos. Skinning: Skin Object Tokens for DotNetNuke 5 (8 videos - 64mins) Free Module: Advanced Optimized Control Panel by Oliver Hine (1 video - 11mins) Module Development Series: Form Validation, Dependant Drop Downs and Data Level Security in OWS (5 videos - 44mins) How to Implement Paging with DotNetMushroom RAD View issue 55 to download all of the videos in one zip file DNN Creative Magazine for DotNetNuke Web Designers Covering DotNetNuke module video reviews, video tutorials, mp3 interviews, resources and web design tips for working with DotNetNuke. In 55 issues we have created 563 videos!Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Entity Object Based on PL/SQL

  - by Manoj Madhusoodanan

  This blog describes how to create a PL/SQL based Entity Object.Oracle application has number of APIs and each API will perform numerous number of tasks.We can create PL/SQL based EO which will directly invoke the PL/SQL stored procedure from the EO. Here I am demonstrating using a standard API FND_USER_PKG.CREATEUSER.This API has x_user_name and x_owner as mandatory parameter.My task is to create a user through OAF page which will accept User Name and Password. Following steps needs to be performed to achieve the above scenario. 1) Create FndUserEO as follows Include all the API parameters and WHO columns in the EO. Make UserName and EncryptedUserPassword ( Here I am not using Encrypted Password. The column name is same as table column so I am keeping the same) column as mandatory. Generate VO. 2) Edit FndUserEOImpl and add the following 3) Attach FndUserVO to AM 4) Create the UI 5) Deploy following files to middle tier and restart the server.  Entity Object: xxcust.oracle.apps.fnd.user.schema.server.FndUserEO.xml xxcust.oracle.apps.fnd.user.schema.server.FndUserEOImpl.java View Object: xxcust.oracle.apps.fnd.user.server.FndUserVO.xml xxcust.oracle.apps.fnd.user.server.FndUserVOImpl.javaUser Interface: xxcust.oracle.apps.fnd.user.webui.CreateFndUserCO.java xxcust.oracle.apps.fnd.user.webui.CreateFndUserPG.xmlYou can test by giving User Name and Password.

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• Changing the material on an object on click in unity

  - by user1509674

  Iam working on unity2d.I have six game object Object1,Object1,Object1,(these are images) ObjectImage1,ObjectImage2,ObjectImage3(these are images). I have arranged the object in the scene as a list one below another Object1 Object2 Object3 When I click the Object1 --- should change to ObjectImage1 Object2 ----should change to ObjectImage2, but the above image of object1(objectImage1) at present should change to Object1 Object3 ----? should change to ObjectImage3,but the above image on object2(objectImage2) should change to Object2 These is similar to selection.I have coded Like when I click of Object2 its changing to ObjectIamge2 but the first object is not changing to object1 from objectImage1.Can anybody help me coding it out. Edit: public GameObject newSprite; private Vector3 currentSpritePosition; void Start() { newSprite.renderer.enabled = false; currentSpritePosition = transform.position; //then make it invisible renderer.enabled = false; //give the new sprite the position of the latter newSprite.transform.position = currentSpritePosition; //then make it visible newSprite.renderer.enabled = true; } void OnMouseExit(){ //just the reverse process renderer.enabled = true; newSprite.renderer.enabled = false; } This is the code used to change the material: public GameObject newSprite; private Vector3 currentSpritePosition; void Start(){ newSprite.renderer.enabled = false; } void OnMouseEnter(){ //getting the current position of the current sprite if ever it can move; currentSpritePosition = transform.position; //then make it invisible renderer.enabled = false; //give the new sprite the position of the latter newSprite.transform.position = currentSpritePosition; //then make it visible newSprite.renderer.enabled = true; } void OnMouseExit(){ //just the reverse process renderer.enabled = true; newSprite.renderer.enabled = false; }

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