Introducing nCoffeeScript: a CoffeeScript compiler for Windows

January 8, 2011 | Jason Kozemczak

The wonderful CoffeeScript turned 1 (dot 0) over the Christmas break. For those who haven’t heard of it yet, I highly recommend you visit the site and look/play around. You can even check out the amazing annotated source for it, courtesy of its primary developer, Jeremy Ashkenas. The documentation is incredible actually.

In case Coffeescript is new to you, it’s a language that looks a lot like the lovechild of Ruby and Python, and it just so happens to compile into Javascript. If you visited the link above, you’d learn that it compiles 1-to-1 into Javascript. CoffeeScript’s compiled output is well-formed and well-performing Javascript. I could go on, but it’s probably best just to go to the site; it’ll do a far better job demonstrating its awesome-ness.

Poor Windows Developers…

CoffeeScript’s command-line compiler is implemented using Node.js; the downside to that fact is that there’s no easy way for Windows developers to integrate CoffeeScript into new and existing web apps. Since CoffeeScript is actually written in Javascript, it can be compiled in the browser, but this isn’t a very practical in an automated build/deploymen environment. CoffeeScript can also be compiled “on the fly” in a client’s browser, but this solution is not a viable production-level option.

Another possible solution is to install Cygwin, compile Node.js, and then download/install CoffeeScript, but this path is long and difficult, and still makes compiling from Windows arduous.

nCoffeeScript to the Rescue

The obvious solution to this problem was to create my own path. As such, I’ve created nCoffeeScript, a CoffeeScript compiler written in .NET for Windows environments! The source can be found on Github. Get the source, build it, and try it out. Let me know what you like and what you wish you could do with it!

I consider nCoffeeScript to be at v0.1 sort of state. I spent a few hours the past two nights getting the main use cases working, but haven’t put that much time into just yet.

Under the covers, nCoffeeScript uses Mozilla’s Rhino. nCoffeeScript interfaces with Rhino using IKVM for Java/.NET interoperability. nCoffeeScript is inspired by jCoffeeScript in its use of Rhino to execute the compilation process in Javascript.

Right now, you can use nCoffeeScript to compile an individual CoffeeScript file; you can also pass it a directory, and nCoffeeScript will compile each CoffeeScript file in the directory into its own Javascript file. By default, nCoffeeScript will wrap the compiled Javascript in a safety function. This wrapper can optionally be left out using the “/nowrap” command-line option.

For more details, visit the Github repo! Hopefully this is one step toward making it trivial to leverage CoffeeScript in our web applications. I hope to follow up with a possible path to utilizing nCoffeeScript in ASP.NET builds/deployments.

Make Your CSS Smarter with Sass

December 16, 2010 | Jason Kozemczak

These days, there is no shortage of “CSS with variables” solutions available to web developers.  Two of the more popular frameworks available today are LESS and Sass.  To be honest, these two options are not all that different (as of v3 of Sass, at least).  Both are supersets of CSS (valid CSS is valid LESS and valid Sass).  Both are Ruby gems, and both share a similar syntax.  Though I’m sure there are subtle differences between the two, I leave it as an exercise for the user to delve into those finer details (maybe you can mention your findings in the comment section?).

I’ve tended to lean towards Sass; the language is a part of the HAML gem, a templating system that allows developers to write templates in a syntax similar to Ruby.  I’ve spent a small amount of time with HAML, and that probably explains why I’m partial to Sass. I’ll walk you through some of Sass’s features and provide a possible solution to leveraging Sass in ASP.NET applications.

Nested Styles

How many times have you written the following?

Granted, my color choices are a bit underwhelming, but that aside, this is certainly not new territory!  With Sass, we can utilize nested styles to better organize our styles.  Combining the power of nested styles and another one of Sass’s features, parent references, we can write the same code in Sass as:

In the above example, we’ve used the & character to reference the parent style element (in this case, anchor elements) Now, as far as total line count, we haven’t really saved ourselves much (1 lousy line).  What we have gained, however, is a deeper abstraction of our various elements’ styling, which is ultimately what we as developers try to do day in and day out.

Variables

Nesting styles alone offers significant leverage, but combining it with the ability to declare variables adds a level of maintainability currently not possible with regular ol’ CSS.  Variables in Sass are prefixed with the $ character; variables can be assigned to text, numbers, etc. WordPress theme writers could really put Sass to work for them:

Functions/Operations

Theme creators might be underwhelmed by my previous example, especially since they can do a “Find all and replace” to change colors out; where they might scratch their heads is Sass’s built-in functions and math operators.  These abstractions allow for easy color manipulation and layout calculations, all handled within the style sheet.

Mixins

Of all of Sass’s features, the one probably most alien to the average person writing CSS is mixins.  For the non-Rubyists out there, mixins is a feature of Ruby that offers a form of inheritance that looks more like composition.  You can read more about it at Pragmatic Programmer’s Guide.  In Sass, mixins allow the developer to define small portions of CSS styling which can then be imported into other styles.  An example will make this more clear:

When the Sass styles are “compiled” down to regular ol’ CSS, the above looks something like this:

… And Much More!

There are a number features available in Sass that I haven’t touched on, including the ability to import other Sass stylesheets, as well as the ability to pass arguments to your mixins.  If you’d like to learn more about Sass, I’d recommend just visiting the site; it undoubtably does a better job describing what it does and examples that better show its utility.  One of the interesting things I thought would be cool to explore is incorporating Sass into ASP.NET web applications by adding the Sass compilation step to the build process in Visual Studio/MSBuild.  I’ll outline the steps to getting this working quickly below.

Sass + ASP.NET

If you’re developing an ASP.NET app, you’re probably working in Windows, so I’m going to target this walkthrough at Windows folks; if you’re doing work in Mono and you’d like instructions on getting this working with Monodevelop or the like, let me know in the comments and I’ll see what I can whip up…

Installing Ruby

If you don’t already have Ruby installed on your machine, you’ll want to install that, as Sass is a Ruby gem.  For a quick and painless install, I’d just go to the RubyInstaller download page, get the newest version (at the time of writing, 1.9.2), and run the installer.

You’ll want to make sure you check the checkbox asking if you want to add Ruby to the Path.  Otherwise, it’s a bit of a pain to use Sass from command line.

Installing the HAML/Sass gem

Once the Ruby installer has finished, open up a command prompt and enter the following command:

gem install haml

This command tells Ruby Gems, a package manager that allows you to install, update, and keep track of the various Ruby libraries (gems), to install the HAML gem; Sass is a part of the HAML gem, so once that has finished we’ll be set as far pre-reqs. As an aside, if your team has a build server, you’ll obviously want to get Ruby/Sass installed on the build server so that it can transform the Sass stylesheets into CSS stylesheets when it comes time to build.  In short, you’ll probably want to install Ruby/Sass locally on your development machine (if you’re doing quick builds to test functionality), as well as the server where the “official” builds are done.

Visual Studio/MSBuild Integration

Now that we’ve got Sass installed, we can begin to leverage it in our ASP.NET web apps.  Let’s start by creating a new web application in Visual Studio:

Create a new folder at the root of the site called “css”.  Right-click on that new folder, and choose “Add -> New Item.”  Choose “Text File” as the filetype and enter “style.scss” as the filename:

One unfortunate side effect of this is that since we’re choosing a filetype of “Text File,” we’re not going to get any of the pretty syntax highlighting we know and love in VS.  Furthermore, we can’t easily associate file extensions with the CSS Editor.  I’ve seen examples on the web of how to do this, but the other caveat is that the code completion engine gets pretty confused by the nested styles, mixins, etc. of Sass, so it’s probably easiest just to leave it be.  If you’re really in need of some syntax highlighting, I’d recommend editing the Sass stylesheet outside of VS using Notepad++.

There’s a nice command built into Sass that will make Sass watch a file or directory for changes to Sass files and automatically compile them as they are updated.  This could be helpful while coding.  “sass –watch [PATH_TO_STYLE_DIR]” will do this for you.

Using the watch command is helpful, but it won’t ensure that your CSS files are always up-to-date, especially if other developers are working on the codebase.  We’ll add a post-build event to our project file so that we can ensure our CSS file is always up-to-date when we build and/or deploy.  Right-click on the web application project file in the Solution Explorer and choose “Properties.”  In the Properties window, click the “Build Events” tab.  In the post-build event command line textbox, enter the following:

sass “$(ProjectDir)css*.scss” “$(ProjectDir)css*.css”

This command will tell Sass to compile all the Sass stylesheets in the “css” folder into CSS files.  This might not be the optimal command if you’re utilizing the @import functionality in Sass and don’t actually want to compile ALL Sass files in that directory.  Edit this command to meeet your needs.  When you’re done, be sure to save.

Before we get on with it, I’m going to add a “style.css” file to the “css” folder.  This is really just going to serve as a placeholder file.  We won’t directly edit it, but it will make it easier to deploy/version control the files if we add it anyway.  Right-click on the “css” folder in Solution Explorer and choose “Add -> New Item”; choose the stylesheet filetype and enter “style.css” as the filename.

Now that we’re squared away, let’s test out what we’ve done.  Open up the “style.scss” file and enter some Sass:

One of the beauties of hooking Sass into the post-build is that we’ll essentially get compile-time validation of our Sass.  If you try to build and get errors, check that Ruby is in the path, that the HAML gem is installed.  Double-check the post-build event command line text; lastly, make sure you Sass is legal!  If you’ve followed the above, you shouldn’t have a problem.

Once we’ve verified our Sass is building correctly, let’s put it to work.  Open the “Default.aspx” file and add a stylesheet link in the document HEAD to the “style.css” file:

<link rel=”Stylesheet” type=”text/css” href=”css/style.css” />

While you’re at it, insert a <p> element into the body of the webform and put some text in it.  Launch the debugger and bask in the glory! Feel free to adapt this method to suit your needs; everybody’s situation is different!

Sass + ASP.NET FTW

Hopefully this post has piqued your interest in Sass and other CSS frameworks.  I’ve given some direction on integrating Sass into ASP.NET applications.  Integrating existing applications would be almost as trivial, as valid CSS is of course valid Sass.  Leveraging the abstractions that Sass allows can help to make for more maintable and more concise styling.

I’ve zipped up the sample web app we created above, you can get it here.  Enjoy!

More Effective .NET via Effective Java: Static Factories

December 14, 2010 | Jason Kozemczak

Yesterday, I talked briefly about one of my favorite takeaways from Joshua Bloch’s Effective Java: the typesafe enum pattern.  Today I’d like to discuss another one of 57 points Bloch discusses in his book and how it can be understood and implemented from a .NET standpoint; the first point he makes in the book is to consider implementing static factory methods in your classes.

When developers start coding a class, we often start with what seems quite innocent:

Now, this is inherently bad, but we lose a certain amount of control over the use of our class when we allow public constructors.  For one, we no longer have control over how many instances of a class we will allow.  This might be important in a situation where we’re managing a pool of database connections, for instance.

Furthermore, if we have enough constructors, we might run into a signature collision, where the only alternative is to rearrange the parameter types of one or more constructors.  This will almost always be a compromise, and probably one that comes with the cost of confusing the consumer of the class.  In short, we’re limited by the fact that classes can only have 1 constructor for any given signature:

But alas, we won’t let the compiler get the best of us!  We can turn our constructors into public static factory methods:

A few things to note about the above example.  One, it doesn’t really make any sense; I haven’t done a good job at making a sensical class, and I apologize for that.  I’ve basically hodge-podged a few static factory methods into a class to point out the advantages vs. traditional object constructors.

Static Factories Over Constructors?

By using static factory methods, we can better manage instances of our class (if we’re concerned about such things), this is highlighted in the top static method.  The beauty of this implementation is that you can adjust the number of allowed instances without the user having to worry about it.  You could even transform the class into a singleton by making adjustments inside the factory method!

The last two static methods are used to highlight the more descriptive nature of static factory methods vs. constructors; it also serves the purpose of showing how signature collissions become essentially a non-issue with static factory methods.  Note that both static factory method’s names help to inform the user certain characteristics of the objects they return.  Additionally, they share the same signature, which would not be possible if constructors had been used in their place.

Another advantage that Bloch points out that I haven’t demonstrated is that using static factory methods allows you the ability to return instances of subclasses in your static factory methods.  I once wrote a small set of classes that calculated the driving distance between two locations using Google Maps and Bing Maps.  I essentially subclassed the interaction between either group and created a static factory method that returned an instance of one or the other.  Generally, it returned only instances of the Bing Maps-based calculator, but could have been easily “switched” out with the Google Maps-based calculator should Bing’s mapping services ever went down.

The Grass is Always Greener

To close, don’t let this post misguide you into thinking that factory methods are always superior to constructors.  One of the major limitations is that without public constructors, you are essentially making your class sealed.  This might potentially be bad if you explicitly want your class to be able to be subclassed.  However, note that this implementation doesn’t stop users from utilizing your class through composition (in contrast to inheritance), which can sometimes be a “cleaner” way of leveraging a class’s behavior.

In addition to the “sealed” byproduct, you also fight the fact that static factory methods don’t “look” any different than other static methods in a class (i.e. they aren’t differentiated from other methods like constructors are).  This could frustrate users of your classes if you aren’t descriptive in your class’s public contract.  Again, use judgement and pragmatism when deciding on implemeting constructors of static factory methods (or maybe use both!).

Effective .NET via Effective Java: Typesafe Enums

December 13, 2010 | Jason Kozemczak

A few weeks ago I bore through Joshua Bloch’s Effective Java.  I’d heard a number of good things about the text, and even though I code professionally in .NET these days, good OO practice is good OO practice regardless of the language.

Bloch’s book is laid out in the same fashion as the classic Effective C++ (Scott Meyers); Bloch lays out 57 suggestions to writing “better” Java code.  One of the ones that gave me an “A ha” moment was Item #21, which presents the “typesafe enum” pattern.  Bloch’s examples are of course in Java, but the pattern can be utilized in .NET (and probably a number of other languages, though I’ll focus on .NET in this post).

Bloch proposes that more often than not, Enums can (and should) be replaced by class behavior.  I’ll present an example to illustrate the advantages to this methodology.

Let’s assume we’re implementing a card game in .NET.  We’d quickly find the need to enumerate the various suits of cards.  It’d probably look something like this

This would probably work well enough, but this doesn’t really get us very far.  Enums can’t implement methods, inherit interfaces, etc.  They’re a little bit more than named integer constants  We can pretty easily get this sort of functionality plus a quite a bit more with just a bit more work.  Now, consider the following class:

What we do by making the constructor private is limit the instantiated instances to only the 4 public facing static instances, which each represent the four suits.  We can now access those instances in a similar fashion to how we access Enum values: Suit.CLUBS, Suit.DIAMONDS, etc.

Now, the above example is somewhat trivial, but where the power lies is that we are now working with dyed-in-the wool classes, so we can add all the instance methods and properties we can dream up.  One of the great bonuses is that since we know there will only be four instances of this class, object equality “just works” since we know that all references to instances of the Suit class will relate back to one of the public-facing four.

We can go even further: since our Suits are now just instances of a class, we can make the Suit class implement any interface we choose, and we can gain the benefits to that implementation (IComparable comes to mind).

One of the other issues Bloch delves in on is the issues around Serialization.  If you are de-serializing instances of the Suit class, this will introduce additional instances of the Suit class; though I’m not going to dive into the details, it’s possible to also overcome issues revolving around that.

I can imagine a number of applications where a typesafe enum class makes more sense than the traditional Enum.  That said, each situation is different, and certainly there are situations where this pattern doesn’t offer any sizable advantages.  Can you think of a time when you used an Enum where the typesafe enum pattern made more sense?  Maybe I haven’t done enough to convince you of the power behind this pattern?  Let me know in the comments!  I might follow up with a more “real world” example where this pattern can be leveraged!

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