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  • Introdução ao NHibernate on TechDays 2010

    - by Ricardo Peres
    I’ve been working on the agenda for my presentation titled Introdução ao NHibernate that I’ll be giving on TechDays 2010, and I would like to request your assistance. If you have any subject that you’d like me to talk about, you can suggest it to me. For now, I’m thinking of the following issues: Domain Driven Design with NHibernate Inheritance Mapping Strategies (Table Per Class Hierarchy, Table Per Type, Table Per Concrete Type, Mixed) Mappings (hbm.xml, NHibernate Attributes, Fluent NHibernate, ConfORM) Supported querying types (ID, HQL, LINQ, Criteria API, QueryOver, SQL) Entity Relationships Custom Types Caching Interceptors and Listeners Advanced Usage (Duck Typing, EntityMode Map, …) Other projects (NHibernate Validator, NHibernate Search, NHibernate Shards, …) ASP.NET Integration ASP.NET Dynamic Data Integration WCF Data Services Integration Comments?

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  • Multiple Object Instantiation

    - by Ricky Baby
    I am trying to get my head around object oriented programming as it pertains to web development (more specifically PHP). I understand inheritance and abstraction etc, and know all the "buzz-words" like encapsulation and single purpose and why I should be doing all this. But my knowledge is falling short with actually creating objects that relate to the data I have in my database, creating a single object that a representative of a single entity makes sense, but what are the best practises when creating 100, 1,000 or 10,000 objects of the same type. for instance, when trying to display a list of the items, ideally I would like to be consistent with the objects I use, but where exactly should I run the query/get the data to populate the object(s) as running 10,000 queries seems wasteful. As an example, say I have a database of cats, and I want a list of all black cats, do I need to set up a FactoryObject which grabs the data needed for each cat from my database, then passes that data into each individual CatObject and returns the results in a array/object - or should I pass each CatObject it's identifier and let it populate itself in a separate query.

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  • Class Design and Structure Online Web Store

    - by Phorce
    I hope I have asked this in the right forum. Basically, we're designing an Online Store and I am designing the class structure for ordering a product and want some clarification on what I have so far: So a customer comes, selects their product, chooses the quantity and selects 'Purchase' (I am using the Facade Pattern - So subsystems execute when this action is performed). My class structure: < Order > < Product > <Customer > There is no inheritance, more Association < Order has < Product , < Customer has < Order . Does this structure look ok? I've noticed that I don't handle the "Quantity" separately, I was just going to add this into the "Product" class, but, do you think it should be a class of it's own? Hope someone can help.

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  • Taking Object Oriented development to the next level

    - by Songo
    Can you mention some advanced OO topics or concepts that one should be aware of? I have been a developer for 2 years now and currently aiming for a certain company that requires a web developer with a minimum experience of 3 years. I imagine the interview will have the basic object oriented topics like (Abstraction, Polymorphism, Inheritance, Design patterns, UML, Databases and ORMs, SOLID principles, DRY principle, ...etc) I have these topics covered, but what I'm looking forward to is bringing up topics such as Efferent Coupling, Afferent Coupling, Instability, The law of Demeter, ...etc. Till few days ago I never knew such concepts existed (maybe because I'm a communication engineer basically not a CS graduate.) Can you please recommend some more advanced topics concerning object oriented programming?

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  • what is message passing in OO?

    - by Tom
    I've been studying OO programming, primarily in C++, C# and Java. I thought I had a good grasp on it with my understanding of encapsulation, inheritance and polymorphism (as well as reading a lot of questions on this site). One thing that seems to popup up here and there is the concept of "message passing". Apparently, this is something that is not used whilst OO programming in today's mainstream languages, but is supported by Smalltalk. My questions are: What is message passing? (Can someone give a practical example?) Is there any support for this "message passing" in C++, C# or Java?

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  • Object Oriented programming on 8-bit MCU Case Study

    - by Calvin Grier
    I see that there's a lot of questions related to OO Programming here. I'm actually trying to find a specific resource related to embedded OO approaches for an 8 bit MCU. Several years back (maybe 6) I was looking for material related to Object Oriented programming for resource constrained 8051 microprocessors. I found an article/website with a case history of a design group that used a very small RAM part, and implemented many Object based constructs during their C design and development. I believe it was an 8051. The project was a success, and managed to stay inside the very small ROM/RAM they had available. I'm attempting to find it again, but Google can't locate it. The article was well written, and recommended a "mixed" approach using C methods for inheritance and encapsulation - if I recall correctly. Can anyone help me locate this article?

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  • Is functional programming a superset of object oriented?

    - by Jimmy Hoffa
    The more functional programming I do, the more I feel like it adds an extra layer of abstraction that seems like how an onion's layer is- all encompassing of the previous layers. I don't know if this is true so going off the OOP principles I've worked with for years, can anyone explain how functional does or doesn't accurately depict any of them: Encapsulation, Abstraction, Inheritance, Polymorphism I think we can all say, yes it has encapsulation via tuples, or do tuples count technically as fact of "functional programming" or are they just a utility of the language? I know Haskell can meet the "interfaces" requirement, but again not certain if it's method is a fact of functional? I'm guessing that the fact that functors have a mathematical basis you could say those are a definite built in expectation of functional, perhaps? Please, detail how you think functional does or does not fulfill the 4 principles of OOP.

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  • Detailed C++ book for a programmer already familiar with C and object-oriented programming?

    - by Anto
    I know (to some extent) a few languages, including C, Java and Python. I'm also (somewhat) familiar with Scala and Scheme, plus I can read (but not write) x86 Assembly. Say I want to learn C++, what is a good book which doesn't try to teach me what a class is, teach me inheritance, polymorphism or loosely coupled classes again, nor does try to teach me other basics, just the C++ language (as well as how to write idiomatic C++ code, not e.g. Java with C++ syntax) and its standard library? Note: "Detailed" as used in the title means that it doesn't try to cover C++ in 100 pages, I want to know the details of the language. Of course, mastery comes from practice, but I don't want to learn just a little bit of C++ from the book, but learn it quite thoroughly.

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  • Is there a programming language with not a tree but tags idea behind OOP?

    - by kolupaev
    I'm thinking about tree structures, and I feel that I don't like them. It's like when you have a shop, then you try to put all products to tree-like catalog, and then you need to place one product to multiple categories, now you have multiple routing, bla-bla. I don't feel like everything in the world could be put to a tree. Instead, I like idea of tags. I would like to store everything with tags. With tags I could do much more. I can even simulate trees if I want. I want to have tag-based filesystem! But hey - modern OOP paradigm with inheritance is based on tree. I want to see how it is when you don't have such basement. Closest thing I found is mixins in some languages. Do you know what else is also about this ideas?

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  • Any enlightenment for understanding Object Oriented Programming? [closed]

    - by ????
    I studied computer science near the end of 1980s, and wasn't taught OOP that formally. With Pascal or C, when I understand the top-down design of functions, and the idea of black box, then everything just seem to make sense, as if there is a "oh I get it!" -- some kind of totally getting it and enlightenment feeling. But with OOP, all I know was the mechanics: the class, instance, method, inheritance, polymorphism, encapsulation. It was like, I knew all the "this is how it is", but never had the feeling of "I totally get it", the enlightened feeling. Would somebody be able to describe it, or point to a chapter in some book or paper which talks about OOP so that the reader can feel: "I totally get it!" on OOP?

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  • Examples of Liskov Substitution

    - by james lewis
    I'm facilitating a session next week on the Liskov Substitution Principle and I was wondering if anyone had any examples of violations 'from the trenches'? I'm looking for something other than uncle Bob's rectangle - square problem and the persistent set problem he talks about in A-PPP (although that is a great example). So far I'm using the example of a (very simple) List and an IndexedList as the 'correct' use of inheritance. And the addition of a Set to this hierarchy as a violation (as a Set is distinct; strengthening the pre condition of the Add method). I've also taken this great example and it's solution from this question Both those examples are great but I'm looking for something more subtle and harder to spot. So far I've come up with nothing so if you've got a great, subtle example post it up. Also, any metaphors you've come across that helped you understand LSP would be really useful too.

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  • What are the basic skills a beginner JavaScript programmer should have?

    - by Sanford
    In NYC, we are working on creating a collaborative community programming environment and trying to segment out software engineers into differing buckets. At present, we are trying to define: Beginners Intermediates Advanced Experts (and/or Masters) Similar to an apprenticeship, you would need to demonstrate specific skills to achieve different levels. Right now, we have identified beginner programming skills as: Object - method, attributes, inheritance Variable - math, string, array, boolean - all are objects Basic arithmetic functions - precedence of functions String manipulation Looping - flow control Conditionals - boolean algebra This is a first attempt, and it is a challenge since we know the natural tension between programming and software engineering. How would you create such a skills-based ranking for JavaScript in this manner? For example, what would be the beginner JavaScript skills that you would need to have to advance to the intermediate training? And so on.

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  • Mapping Help in the EDM Designer

    The mapping details window that displays the mappings between an entity and database table(s) is pretty straightforward. When you join two related tables in a Table Per Hierarchy inheritance things can get a little confusing when it comes to the mappings for inherited properties. But did you know that the Mapping Details window uses the Properties window to help? Here are two entities in a TPH hierarchy. Customer inherits Contact. Customer maps to a Customers table which uses ContactID as...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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  • Why are interfaces useful?

    - by Pankaj Upadhyay
    I have been studying and coding in C# for some time now. But still, I can't figure the usefulness of Interfaces. They bring too little to the table. Other than providing the signatures of function, they do nothing. If I can remember the names and signature of the functions which are needed to be implemented, there is no need for them. They are there just to make sure that the said functions(in the interface) are implemented in the inheriting class. C# is a great language, but sometimes it gives you the feeling that first Microsoft creates the problem (not allowing multiple inheritance) and then provides the solution, which is rather a tedious one. That's my understanding which is based on limited coding experience. What's your take on interfaces? How often you make uses of them and what makes you do so?

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  • When to use mixins in Ruby

    - by Gilles
    I am wondering when to use mixins? I have read about them. Many authors compare them to interfaces, abstract classes, etc. Mixins are modules that are mixed-in and modules are a way to group similar methods, constants and classes together. I have seen examples where a module for math functions is created. It makes sense to group and reuse such functions but should I only mix these in a class if I am faced with an inheritance situation? Should I mix these in anytime I want to use them in a class? Should they be used exactly like interfaces in other languages or are there other subtleties?

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  • What are the basic skills a BEGINNING JavaScript programmer should have?

    - by Sanford
    In NYC, we are working on creating a collaborative community programming environment and trying to segment out software engineers into differing buckets. At present, we are trying to define: Beginners Intermediates Advanced Experts (and/or Masters) Similar to an apprenticeship, you would need to demonstrate specific skills to achieve different levels. Right now, we have identified Beginner programming skills as: Object - method, attributes, inheritance Variable - math, string, array, boolean - all are objects Basic arithmetic functions - precedence of functions String manipulation Looping - flow control Conditionals - boolean algebra This is a first attempt, and it is a challenge since we know the natural tension between programming and software engineering. How would you create such a skills-based ranking for JavaScript in this manner? For example, what would be the Beginner Javascript skills that you would need to have to advance to the Intermediate Training? And so on.

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  • Plan variable and call dependencies

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

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  • Is OO-programming really as important as hiring companies place it?

    - by ale
    I am just finishing my masters degree (in computing) and applying for jobs.. I've noticed many companies specifically ask for an understanding of object orientation. Popular interview questions are about inheritance, polymorphism, accessors etc. Is OO really that crucial? I even had an interview for a programming job in C and half the interview was OO. In the real world, developing real applications, is object orientation nearly always used? Are key features like polymorphism used A LOT? I think my question comes from one of my weaknesses.. although I know about OO.. I don't seem to be able to incorporate it a great deal into my programs. I would be really interested to get peoples' thoughts on this!

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  • Liskov substitution principle with abstract parent class

    - by Songo
    Does Liskov substitution principle apply to inheritance hierarchies where the parent is an abstract class the same way if the parent is a concrete class? The Wikipedia page list several conditions that have to be met before a hierarchy is deemed to be correct. However, I have read in a blog post that one way to make things easier to conform to LSP is to use abstract parent instead of a concrete class. How does the choice of the parent type (abstract vs concrete) impacts the LSP? Is it better to have an abstract base class whenever possible?

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  • Who could ask for more with LESS CSS? (Part 1 of 3&ndash;Features)

    - by ToStringTheory
    It wasn’t very long ago that I first began to get into CSS precompilers such as SASS (Syntactically Awesome Stylesheets) and LESS (The Dynamic Stylesheet Language) and I had been hooked on the idea since.  When I finally had a new project come up, I leapt at the opportunity to try out one of these languages. Introduction To be honest, I was hesitant at first to add either framework as I didn’t really know much more than what I had read on their homepages, and I didn’t like the idea of adding too much complexity to a project - I couldn’t guarantee I would be the only person to support it in the future. Thankfully, both of these languages just add things into CSS.  You don’t HAVE to know LESS or SASS to do anything, you can still do your old school CSS, and your output will be the same.  However, when you want to start doing more advanced things such as variables, mixins, and color functions, the functionality is all there for you to utilize. From what I had read, SASS has a few more features than LESS, which is why I initially tried to figure out how to incorporate it into a MVC 4 project. However, through my research, I couldn’t find a way to accomplish this without including some bit of the Ruby on Rails framework on the computer running it, and I hated the fact that I had to do that.  Besides SASS, there is little chance of me getting into the RoR framework, at least in the next couple years.  So in the end, I settled with using LESS. Features So, what can LESS (or SASS) do for you?  There are several reasons I have come to love it in the past few weeks. 1 – Constants Using LESS, you can finally declare a constant and use its value across an entire CSS file. The case that most people would be familiar with is colors.  Wanting to declare one or two color variables that comprise the theme of the site, and not have to retype out their specific hex code each time, but rather a variable name.  What’s great about this is that if you end up having to change it, you only have to change it in one place.  An important thing to note is that you aren’t limited to creating constants just for colors, but for strings and measurements as well. 2 – Inheritance This is a cool feature in my mind for simplicity and organization.  Both LESS and SASS allow you to place selectors within other selectors, and when it is compiled, the languages will break the rules out as necessary and keep the inheritance chain you created in the selectors. Example LESS Code: #header {   h1 {     font-size: 26px;     font-weight: bold;   }   p {     font-size: 12px;     a     {       text-decoration: none;       &:hover {         border-width: 1px       }     }   } } Example Compiled CSS: #header h1 {   font-size: 26px;   font-weight: bold; } #header p {   font-size: 12px; } #header p a {   text-decoration: none; } #header p a:hover {   border-width: 1px; } 3 - Mixins Mixins are where languages like this really shine.  The ability to mixin other definitions setup a parametric mixin.  There is really a lot of content in this area, so I would suggest looking at http://lesscss.org for more information.  One of the things I would suggest if you do begin to use LESS is to also grab the mixins.less file from the Twitter Bootstrap project.  This file already has a bunch of predefined mixins for things like border-radius with all of the browser specific prefixes.  This alone is of great use! 4 – Color Functions This is the last thing I wanted to point out as my final post in this series will be utilizing these functions in a more drawn out manner.  Both LESS and SASS provide functions for getting information from a color (R,G,B,H,S,L).  Using these, it is easy to define a primary color, and then darken or lighten it a little for your needs.  Example: Example LESS Code: @base-color: #111; @red:        #842210; #footer {   color: (@base-color + #003300);   border-left:  2px;   border-right: 2px;   border-color: desaturate(@red, 10%); } Example Compiled CSS: #footer {    color: #114411;    border-left:  2px;    border-right: 2px;    border-color: #7d2717; } I have found that these can be very useful and powerful when constructing a site theme. Conclusion I came across LESS and SASS when looking for the best way to implement some type of CSS variables for colors, because I hated having to do a Find and Replace in all of the files using the colors, and in some instances, you couldn’t just find/replace because of the color choices interfering with other colors (color to replace of #000, yet come colors existed like #0002bc).  So in many cases I would end up having to do a Find and manually check each one. In my next post, I am going to cover how I’ve come to set up these items and the structure for the items in the project, as well as the conventions that I have come to start using.  In the final post in the series, I will cover a neat little side project I built in LESS dealing with colors!

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  • SharePoint Database security corruption

    - by H(at)Ni
    Hello, One time I faced an issue where my customer is having an HTTP 500 internal server error while trying to access any SharePoint site. The problem appeared once he moved back and forth with inheriting/breaking inheritance of permissions over different levels in the site collection. "Security corruption in database" sounds very tough for a customer running a production portal with a backup that can make him lose around 3 weeks of valuable data. However, the solution tends not to be that hard, there's an stsadm command that help us detect the corruption and even delete the orphaned items causing the corruption. Follow these steps: a. stsadm -o databaserepair -url http://SITEURL -databasename DBNAME                and it returned some orphaned items.            b. stsadm -o databaserepair -url http://SITEURL -databasename DBNAME -deletecorruption                and it removed the orphaned items. Cheers,

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  • Criteria for a language to be considered "object oriented"

    - by nist
    I had a discussion about OO programming today and by browsing the internet I found a lot of different specifications for object oriented languages. What are the requirements for a language to be object oriented? For myself an object oriented language must have classes, inheritance and encapsulation. Is C an object oriented language just because you can use structs and program with an object oriented design? Why/ why not? Are there any good sites/articles about this? And please, no Wikipedia links because I've already been there.

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  • Where, in an object oriented system should you, if at all, choose (C-style) structs over classes?

    - by Anto
    C and most likely many other languages provide a struct keyword for creating structures (or something in a similar fashion). These are (at least in C), from a simplified point of view like classes, but without polymorphism, inheritance, methods, and so on. Think of an object-oriented (or multi paradigm) language with C-style structs. Where would you choose them over classes? Now, I don't believe they are to be used with OOP as classes seem to replace their purposes, but I wonder if there are situations where they could be preferred over classes in otherwise object-oriented programs and in what kind of situations. Are there such situations?

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  • Should Equality be commutative within a Class Hierachy?

    - by vossad01
    It is easy to define the Equals operation in ways that are not commutative. When providing equality against other types, there are obviously situations (in most languages) were equality not being commutative is unavoidable. However, within one's own inheritance hierarchy where the root base class defines an equality member, a programmer has more control. Thus you can create situations where (A = B) ? (B = A), where A and B both derive from base class T Substituting the = with the appropriate variation for a given language. (.Equals(_), ==, etc.) That seems wrong to me, however, I recognize I may be biased by background in Mathematics. I have not been in programming long enough to know what is standard/accepted/preferred practice when programming. Do most programmers just accept .Equals(_)may not be commutative and code defensibly. Do they expect commutativity and get annoyed if it is not. In short, when working in a class hierarchy, should effort me made to ensure Equality is commutative?

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  • How to learn programming from very basic level to advanced level? [closed]

    - by user1022209
    I know many programming languages ,skills and concepts in very basic, such as PHP, Java, Object-oriented technology. Using PHP, I can build a simple website with CRUD, login function. Using Java, I can make an basic swing csv/plain text editor in which user can switch between 2 different views. In term of object-oriented Technology, I clearly understand what encapsulation, inheritance and Polymorphism are I want to know more about programming. Sometimes I "google" some of the topics I am interested at , the more I see on the internet, the more I feel I am a small potato in the world ( indeed I am ). The codings/concepts are difficult to understand. I lacks confidence right now so I am asking this question :( What is the best way to learn programming to advanced level? Just buy a book and read it page to page? Thanks for any helps

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