**Factory**: Assembles classes, either by composing a bunch of bits together, or choosing type based on some kind of context

**Provider**: Provider is something microsoft &quot;invented&quot; (basically an abstract factory pattern) that is a way of doing a factory of factories, or having a common factory interface which allows factories to be swappable. It is used all over in the MS web stack as a way to keep components configurable.

**Service**: A service is a group of related functionality. Think of it as if you are splitting your architecture horizontally, you have a &quot;Business Logic&quot; layer, if you split that vertically you will have services.

Somehow when I `git init`ed my latest project a month or so ago I ran the command in the directory one directory higher than the root of my project.

So my repository is in the `./project` directory and not the `./project/my-new-project` directory.  I don&#39;t know how I didn&#39;t realize the issue earlier, but I just never looked for the .git directory until now.

Is there a way, without killing my project, to move the repository to the proper directory and then tell git what the new base of the project is?  Just moving the directory doesn&#39;t work.  Git thinks all files have been deleted.

My Git repository is in the wrong root directory. Can I move it? (../ instead of ./)

Say I&#39;m building a board game with a hextile grid, like [_Settlers of Catan_][1]:

&lt;img src=&quot;http://imgur.com/QA5nE.jpg&quot; alt=&quot;Hosted by imgur.com&quot; /&gt;

Note that each vertex and edge may have an attribute (a road and settlement above).

How would I make a data structure which represents this board? What are the patterns for accessing each tile&#39;s neighbors, edges and vertices?

  [1]: http://en.wikipedia.org/wiki/The_Settlers_of_Catan

How do I represent a hextile/hex grid in memory?

What is the difference between the terms Factory, Provider and Service?

Just getting into NHibernate and its Repository pattern (POCO classes, etc).

Difference between a Factory, Provider and a Service?

<p>What is the difference between the terms Factory, Provider and Service?</p>
<p>Just getting into NHibernate and its Repository pattern (POCO classes, etc).</p>


A long time ago I have read an article (I believe a blog entry) which put me on the &quot;right&quot; track on naming objects: Be very very scrupulous about naming things in your program.

For example if my application was (as a typical business app) handling users, companies and addresses I&#39;d have a `User`, a `Company` and an `Address` domain class - and probably somewhere a `UserManager`, a `CompanyManager` and an `AddressManager` would pop up that handles those things.

So can you tell what those `UserManager`, `CompanyManager` and `AddressManager` do? No, because Manager is a very very generic term that fits to anything you can do with your domain objects.

The article I read recommended using very specific names. If it was a C++ application and the `UserManager`&#39;s job was allocating and freeing users from the heap it would not manage the users but guard their birth and death. Hmm, maybe we could call this a `UserShepherd`.

Or maybe the `UserManager`&#39;s job is to examine each User object&#39;s data and sign the data cryptographically. Then we&#39;d have a `UserRecordsClerk`.


Now that this idea stuck with me I try to apply it. And find this simple idea amazingly hard.

I can describe what the classes do and (as long as I don&#39;t slip into quick &amp; dirty coding) the classes I write do exactly **one** thing. What I miss to go from that description to the names is a kind of catalogue of names, a vocabulary that maps the concepts to names.

Ultimately I&#39;d like to have something like a pattern catalogue in my mind (frequently design patterns easily provide the object names, e.g. a _factory_)


- Factory - Creates other objects (naming taken from the design pattern)
- Shepherd - A shepherd handles the lifetime of objects, their creation and shutdown
- Synchronizer - Copies data between two or more objects (or object hierarchies)
- Nanny - Helps objects reach &quot;usable&quot; state after creation - for example by wiring to other objects

- etc etc.


So, how do you handle that issue? Do you have a fixed vocabulary, do you invent new names on the fly or do you consider naming things not-so-important or wrong?


P.S.: I&#39;m also interested in links to articles and blogs discussing the issue. As a start, here is the original article that got me thinking about it: [Naming Java Classes without a &#39;Manager&#39;][1]


----------


## Update: Summary of answers ##

Here&#39;s a little summary of what I learned from this question in the meantime.

 - Try not to create new metaphors (Nanny)
 - Have a look at what other frameworks do

Further articles/books on this topic:

 - [What names do you find yourself prepending/appending to classes regularly?][2] 
 - [What’s the best approach to naming classes?][3]
 - Book: [Design Patterns: Elements of Reusable Object-Oriented Software (Hardcover)][4]
 - Book: [Patterns of Enterprise Application Architecture (Hardcover)][5]
 - Book: [Implementation Patterns (Paperback)][6]


And a current list of name prefixes/suffixes I collected (subjectively!) from the answers:

 - Coordinator
 - Builder
 - Writer
 - Reader
 - Handler
 - Container
 - Protocol
 - Target
 - Converter
 - Controller
 - View
 - Factory
 - Entity
 - Bucket
 

And a good tip for the road:

&gt; Don&#39;t get naming paralysis. Yes, names are very important but they&#39;re not important   enough to waste huge amounts of time on. If you can&#39;t think up a good name in 10 minutes, move on.

  [1]: http://www.bright-green.com/blog/2003_02_25/naming_java_classes_without_a.html
  [2]: https://stackoverflow.com/questions/1194403/what-names-do-you-find-yourself-prepending-appending-to-classes-regularly
  [3]: https://stackoverflow.com/questions/38019/whats-the-best-approach-to-naming-classes
  [4]: http://www.amazon.com/dp/0201633612/
  [5]: http://www.amazon.com/Patterns-Enterprise-Application-Architecture-Martin/dp/0321127420
  [6]: http://www.amazon.com/Implementation-Patterns-Kent-Beck/dp/0321413091

Naming Classes - How to avoid calling everything a &quot;&lt;WhatEver&gt;Manager&quot;?

I have recently been studying UML and drawing simple diagrams with ordinary plain arrows between classes, but I know it&#39;s not enough. There are plenty of other arrows: generalization, realisation and etc. which have meaning to the diagram reader. 

Is there a nice resource which could explain each arrow (ordinary, plain, dotted, diamond-filled, diamond)? 

It would be the best if it will have some code examples for them.

Explanation of the UML arrows

Is it possible in PHP 5 to have an interface that has private / protected methods?

Right now I have:

    interface iService
    {
        private method1();
    }

That throws an error:

&gt; Parse error: syntax error, unexpected T_STRING, expecting T_VARIABLE


I just want to have confirmation that it is the case that an interface can only contain public methods.

Is it possible to have an interface that has private / protected methods?

What is a covariant return type in Java?  In object-oriented programming in general?

What is a covariant return type?

I wrote the below code in order to explain my issue. If I comment the line 11 (with the keyword &quot;using&quot;), the compiler does not compile the file and displays this error: `invalid conversion from &#39;char&#39; to &#39;const char*&#39;`. It seems to not see the method `void action(char)` of the `Parent` class in the `Son` class. 
 
Why the compiler behave this way? Or have I done something wrong?

    class Parent
    {
    	public:
    		virtual void action( const char how ){ this-&gt;action( &amp;how ); }
    		virtual void action( const char * how ) = 0;
    };
    
    class Son : public Parent
    {
    	public:
    		using Parent::action; // Why should i write this line?
    		void action( const char * how ){ printf( &quot;Action: %c\n&quot;, *how ); }
    };
    
    int main( int argc, char** argv )
    {
    	Son s = Son();
    	s.action( &#39;a&#39; );
    	return 0;
    }

Why should I use the &quot;using&quot; keyword to access my base class method?

According to [Sun][1] and [Msdn][2] it is a design pattern.

According to [Wikipedia][3] it is an architectural pattern

&gt; In comparison to design patterns, architectural patterns are larger in scale.
(Wikipedia - [Architectural pattern][4])

**Or it is an architectural pattern that also has a design pattern ?**

Which one is true ?


  [1]: http://java.sun.com/blueprints/patterns/MVC.html
  [2]: http://msdn.microsoft.com/en-us/library/ms978748.aspx
  [3]: http://en.wikipedia.org/wiki/Model–view–controller
  [4]: http://en.wikipedia.org/wiki/Architectural_pattern_(computer_science)

Is MVC a Design Pattern or Architectural pattern

Are there any exemplary examples of the GoF Observer implemented in Python?  I have a bit code which currently has bits of debugging code laced through the key class (currently generating messages to stderr if a magic env is set). Additionally, the class has an interface for incrementally return results as well as storing them (in memory) for post processing.  (The class itself is a job manager for concurrently executing commands on remote machines over ssh).

Currently the usage of the class looks something like:

    job = SSHJobMan(hostlist, cmd)
    job.start()
    while not job.done():
        for each in job.poll():
            incrementally_process(job.results[each])
            time.sleep(0.2) # or other more useful work
    post_process(job.results)

An alernative usage model is:

    job = SSHJobMan(hostlist, cmd)
    job.wait()  # implicitly performs a start()
    process(job.results)

This all works fine for the current utility.  However it does lack flexibility.  For example I currently support a brief output format or a progress bar as incremental results, I also support
brief, complete and &quot;merged message&quot; outputs for the `post_process()` function.

However, I&#39;d like to support multiple results/output streams (progress bar to the terminal, debugging and warnings to a log file, outputs from successful jobs to one file/directory, error messages and other results from non-successful jobs to another, etc).

This sounds like a situation that calls for Observer ... have instances of my class accept registration from other objects and call them back with specific types of events as they occur.

I&#39;m looking at [PyPubSub](http://pypi.python.org/pypi/PyPubSub/) since I saw several references to that in SO related questions.  I&#39;m not sure I&#39;m ready to add the external dependency to my utility but I could see value in using their interface as a model for mine if that&#39;s going to make it easier for others to use.  (The project is intended as both a standalone command line utility and a class for writing other scripts/utilities).

In short I know how to do what I want ... but there are numerous ways to accomplish it.  I want suggestions on what&#39;s most likely to work for other users of the code in the long run.

The code itself is at: [classh](http://bitbucket.org/jimd/classh).




Python Observer Pattern: Examples, Tips?

I&#39;m trying to get my head around how to properly use the repository pattern. The central concept of an Aggregate Root keeps coming up. When searching both the web and Stack Overflow for help with what an aggregate root is, I keep finding discussions about them and dead links to pages that are supposed to contain base definitions.

In the context of the repository pattern, **what is an aggregate root?**

What&#39;s an Aggregate Root?

I like MVVM. I don&#39;t love it, but like it. Most of it makes sense. But, I keep reading articles that encourage you to write a lot of code so that you can write XAML and don&#39;t have to write any code in the code-behind.

Let me give you an example.

Recently I wanted to hookup a command in my ViewModel to a ListView MouseDoubleClickEvent. I wasn&#39;t quite sure how to do this. Fortunately, Google has answers for everything. I found the following articles:

 - http://blog.functionalfun.net/2008/09/hooking-up-commands-to-events-in-wpf.html
 - http://joyfulwpf.blogspot.com/2009/05/mvvm-invoking-command-on-attached-event.html
 - http://sachabarber.net/?p=514
 - http://geekswithblogs.net/HouseOfBilz/archive/2009/08/27/adventures-in-mvvm-ndash-binding-commands-to-any-event.aspx
 - http://marlongrech.wordpress.com/2008/12/13/attachedcommandbehavior-v2-aka-acb/
 
While the solutions were helpful in my understanding of commands, there were problems. Some of the aforementioned solutions rendered the WPF designer unusable because of a common hack of appending &quot;Internal&quot; after a dependency property; the WPF designer can&#39;t find it, but the CLR can. Some of the solutions didn&#39;t allow multiple commands to the same control. Some of the solutions didn&#39;t allow parameters.

After experimenting for a few hours I just decided to do this:

    private void ListView_MouseDoubleClick(object sender, MouseButtonEventArgs e) {
        ListView lv = sender as ListView;
        MyViewModel vm = this.DataContext as MyViewModel;

        vm.DoSomethingCommand.Execute(lv.SelectedItem);
    }


So, MVVM purists, please tell me what&#39;s wrong with this? I can still Unit test my command. This seems very practical, but seems to violate the guideline of &quot;ZOMG... you have code in your code-behind!!!!&quot; Please share your thoughts.

Thanks in advance.


 

MVVM Madness: Commands

I saw this code work with LINQ to SQL but when I use Entity Framework, it throws this error:

&gt;LINQ to Entities does not recognize the method &#39;System.Linq.IQueryable&#39;1[MyProject.Models.CommunityFeatures] GetCommunityFeatures()&#39; method, and this method cannot be translated into a store expression.`


The repository code is this:

    public IQueryable&lt;Models.Estate&gt; GetEstates()
    {
        return from e in entity.Estates
               let AllCommFeat = GetCommunityFeatures()
               let AllHomeFeat = GetHomeFeatures()
               select new Models.Estate
                          {
                                    EstateId = e.EstateId,
                                    AllHomeFeatures = new LazyList&lt;HomeFeatures&gt;(AllHomeFeat),
                                    AllCommunityFeatures = new LazyList&lt;CommunityFeatures&gt;(AllCommFeat)
                          };
    }

    public IQueryable&lt;Models.CommunityFeatures&gt; GetCommunityFeatures()
    {
        return from f in entity.CommunityFeatures
               select new CommunityFeatures
                          {
                              Name = f.CommunityFeature1,
                              CommunityFeatureId = f.CommunityFeatureId
                          };
    }

    public IQueryable&lt;Models.HomeFeatures&gt; GetHomeFeatures()
    {
        return from f in entity.HomeFeatures
               select new HomeFeatures()
               {
                   Name = f.HomeFeature1,
                   HomeFeatureId = f.HomeFeatureId
               };
    }


LazyList is a List that extends the power of IQueryable.

Could someone explain why this error occurs?

Method cannot be translated into a store expression

In OOP Design Patterns, what is the difference between the Repository Pattern and a Service Layer?

I am working on an ASP.NET MVC 3 app, and am trying to understand these design patterns, but my brain is just not getting it...yet!!

Difference between Repository and Service Layer?

I am using the Generic Repository pattern on top of Entity Framework Code First. Everything was working fine until I needed to include more entities in a query. I got to include one entity successfully, but now I can&#39;t figure out how to include multiple entities. Check out what I&#39;ve got so far:

    public IQueryable&lt;TEntity&gt; GetQuery&lt;TEntity&gt;() where TEntity : class
    {
        var entityName = GetEntityName&lt;TEntity&gt;();
        return _objectContext.CreateQuery&lt;TEntity&gt;(entityName);
    }
    
    public IList&lt;TEntity&gt; GetQueryWithInclude&lt;TEntity&gt;(string toInclude) where TEntity : class
    {
        var entityName = GetEntityName&lt;TEntity&gt;();
        return _objectContext.CreateQuery&lt;TEntity&gt;(entityName).Include(toInclude).ToList();
    }
    
    private string GetEntityName&lt;TEntity&gt;() where TEntity : class
    {
        return string.Format(&quot;{0}.{1}&quot;, _objectContext.DefaultContainerName, _pluralizer.Pluralize(typeof(TEntity).Name));
    }

What I tried to do but didn&#39;t work was pass in an array of strings into a function, then try to &quot;append&quot; the includes on top of the query. I was wondering what if I called the GetQueryWithInclude and passed an entity name (actually a navigation property) at a time to aggregate the results of the query, but I&#39;m worried this might duplicate the results of the query on each call... What do you think would be the best way to get this to work?

Thanks in advance!

**UPDATE:**

Here&#39;s an example of what I&#39;m trying to achieve:


    public IQueryable GetQueryWithIncludes(string[] otherEntities)
    {
        var entityName = GetEntityName&lt;TEntity&gt;();
        //now loop over the otherEntities array 
        //and append Include extensions to the query
        //so inside the loop, something like: 
        _objectContext.GetQuery&lt;TEntity&gt;(entityName).Include(otherEntities[index]);
    }

EF Including Other Entities (Generic Repository pattern)

As i dig deeper in to the DbContext, DbSet and associated interfaces, I am wondering why you would need to implement a separate &quot;Generic&quot; Repository around these implementations?

It looks like DbContext and IDbSet do everything you need and include the &quot;Unit Of Work&quot; inside DbContext.

Am I missing something here or does it seem people enjoy adding another layer of dependency for no reason.

Content Type	Original Author	Original Content on Stackoverflow
Question	mrblah	View Question on Stackoverflow
Solution 1 - Oop	Matt Briggs	View Answer on Stackoverflow

Difference between a Factory, Provider and a Service?

Oop Problem Overview

Oop Solutions

Solution 1 - Oop

How do I represent a hextile/hex grid in memory?

My Git repository is in the wrong root directory. Can I move it? (../ instead of ./)

Attributions