作者：未知 来源：月光软件站 加入时间：2005-2-28　月光软件站

Feedback on "Ten Things a Java Programmer Should Know About Ruby"

This is a compilation of feedback I received for a list of things Java programmers should be aware of when looking at Ruby. This list is not the final version, nor are all (most) of the ideas in this list mine. This is merely a temporarty holding spot for these ideas while I assemble a talk/article/presentation on the topic.

If you have a problem with anything on this list, please bring it up with the person who made the suggestion (i.e. not me!)

However, if you have further suggestions for this list, feel free to drop me a note at [email protected].

	Boolean methods end in ?. Dangerous methods end in !
	you can fit in your mind and write code without looking at the docs every six minutes
	less syntax and less typing
	Discipline. Because of its inherent flexibility, Ruby require more self-discipline
	"." (dot) is a method call operator. "::" (colon-colon) is a scope operator.
	Ruby classes are Objects (therefore String.new, not new String())
	Everything is an Object
	Ruby does not have type casting.
	Compared to Java, XML is agile. Compared to Ruby, XML is Heavy.
	Ruby has O/R mappers, so find your Ruby "hibernate", but drop any preconceptions.
	Don't worry about early performance optimization
	Enjoy closures and blocks
	No method overloading
	Don't worry about interfaces, enjoy Duck Typing.
	Reflection in Ruby is much easier than in Java, and more deeply into the language than the java.lang.reflect tack-on.
	That you can write Ruby in Java (http://jruby.sourceforge.net)
	Everything is an expression.
	local_variable, @instance_variable, $global_variable, Constants, (and @@class_variables)
	Java static methods do not (quite) translate to Ruby class methods.
	you can have variable number of parameters, and multiple return values
	Ruby is not a Silver Bullet, unlike Java, right? :-)
	Ruby is a language to be used everywhere. You use it even in templates. No need for "Velocity/JSP."
	Web-development is possible with other languages besides Java.
	Many things that you're used to thinking of as syntax are now just
	Ruby is strongly typed, not statically typed
	Ruby has extensive reflection capabilities
	Ruby is dynamic. You can add, remove and modify objects, classes and methods at runtime.
	REXML vs. JAXP. I rest my case.
	KISS
	Think in terms of methods (behaviors) instead of classes.
	you cannot rely on the compiler to catch trivial mistakes
	No explicit types. Probably the most disconcerting thing for a javahead
	ruby has shortcuts for accessor methods which reduces alot of redundant coding in java
	you can use string interpolation, ex: "x: #{@myvar}" instead of having to say "x:" + myvar'
	no semi-colons, optional parenthesis
	Ruby classes are always "open".
	C extensions/wrappers are *much* easier in Ruby than JNI interfaces in Java
	Ruby has MVC and OO programming and libraries, but drop any preconceptions.
	In Ruby data is strongly typed, but variables are *not*
	Once you start coding Ruby, going back to Java is painful.
	CamelCase for class names, names_with_underscores for methods and variables.
	stop writing so much code
	ri is your friend. irb is your other friend.
	eval
	the builtin classes are much faster because they're written in C and not Ruby
	Avoid external utility classes
	Use class methods to define pseudo-compile directives
	You probably don't need Factories
	Enumerable is your friend
	Typing is the enemy
	No external configuration files
	method_missing
	Singleton methods
	Ruby packaging vs Java packaging
	ruby has multiple inheritance through mixins (this is sooo nice to have)
	writing code in ruby, can improve the code you write in java
	Ruby is agile, perfectly suited for XP
	Ruby's OO is message based.
	Fixed what's wrong with Perl
	Fixes what's wrong with Python
	It's super productive (like Perl, Python and Smalltalk)- maybe 5-10x Java.
	Is a lot like Smalltalk, but doesn't look as funny
	Is a lot like JavaScript, but more OO and more for ful app development
	Blocks and Closures
	Open Classes
	Duck Typing
	"finally" is called "ensure"
	Use blocks for transactional behavior like like File.open does.
	Help at: http://ruby-lang.org/en, http://ruby-doc.org/, news:comp.lang.ruby, irc:ruby-talk
	An instance of a class can be extended to be subtly different, without needing to subclass.
	you can change your mind about whether .foo is a simple property or a complex method call, without affecting the interface to your class.
	HEREDOC strings with variable interpolation make large chunks of output really easy to construct.
	For good (but subtle) reasons, you have to leave the '++' and '--' behind.

Top 10 Things I Like About Subversion

I've been using Subversion for over two months as my repository on a project at work and I've recently transitioned all of my personal projects on my Powerbook from CVS to Subversion. I'm really digging Subversion and can't imagine or remember what it was like before I found it.

I wrote this up a few days ago for a meeting at work and thought I'd share it with everyone in blogspace. In no particular order, here are the top 10 things I like about Subversion:

1. Atomic Commits: It's all or nothing! If even one file out of 100 has troubles, then nothing gets committed. My repository is never in an inconsistent state.
2. Tools Support: If you don't like the command line (and I do), then you have Tortoise. But since I'm an Eclipse user, I tend to enjoy Subclipse (I've read several people who say that Subclipse has problems, but I've had nothing but success with it for over two months).
3. Hooks: Automatically kick off a build, fire an e-mail, or update my issue tracking system...just by committing some files.
4. Web-browsable Repository: Without having to do much additional setup (other than Apache), I get to browse my repository via my favorite web-browser.
5. Easy branching/tagging/merging: I create a new tag or branch by simply making a logical copy in the repository. Couldn't be smoother.
6. Efficient handling of binary files: It's my understanding that binary files are stored based on binary diffs to be more efficient.
7. Everything is versioned: Even directories and meta-data.
8. Externals: I haven't had the privilege of using externals yet, but they sound darn cool. Check out a project and all other projects that it depends on all at once.
9. Concurrent versioning: Just like CVS. I don't have to lock something before I can commit changes.
10. Easy refactoring: I can rename a file or repackage a class and Subversion's smart enough to keep keep the file's history.

And for an eleventh thing that I like: I've got an excellent Subversion book to help me out.

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