Ruby 1.8.0 Released

waieitch writes "A long-waited new version of the scripting language, Ruby 1.8.0 has just been released. You can download from here, and the changelog is available. With many new libraries, say dRuby, ERB, REXML, this version is doubled by 1.6.8 in size."

Comments

Best. Clause. Evar.

[gazbo]

this version is doubled by 1.6.8 in size

No more text.

Former perl, python, java geek gone to Ruby

[Fished]

For what it's worth, I've been using ruby for about six months, and am totally hooked. It is easily the best language I've ever used. Things that are idiosyncratic and difficult in other languages just flow in ruby. There are also many features to facilitate the way you actually *use* objects (e.g. to do object attributes, all you have to do is add "attr_writer attribute1, attribute2, attribute3" and "attr_reader attribute1, attribute2, attribute3") to the class defs. No more endless get and set functions all of which are more or less identical!

This language is definitely worth a look. It's not just a python knock-off, as many have supposed -- it offers features python doesn't.

Re:Former perl, python, java geek gone to Ruby

[MarkusQ]

it had the same conceptual structure as Python, but the cryptic syntax of perl

I'm not sure what language you looked at, but it doesn't sound like ruby.

• Ruby is a deeply object oriented in the tradition of smalltalk; python is a superfically object oriented language more in the tradition of C++ or object pascal. Until recently, for example, you could not derive your own classes from the built in classes.
• The basic syntax of ruby is very clean (a fact which is somewhat obscured by the "syntactic sugar" provided for some commonly used features (such as operators) and the provision of aliases for some global objects that are intended to ease the transition from perl). The basic syntax is:

  method_call ::= object.method_name arg1,arg2,...argn

  where object, method_name, and the arguments can all objects and can be given by named constants, literals, variables, or expressions (method calls). The only thing I really miss from python is the indentation (or rather, not having to explicitly delimit blocks, since I indent that way even when I don't have to).

-- MarkusQ

Re:Former perl, python, java geek gone to Ruby

[tigersha]

The major improvement in Ruby over Python and C++ and most OO languages (but not Smalltalk) is the inclusion of code blocks that may be passed in as a parameter to a method and its widespread use throughout the libraries.

For a simple example, look at this:

x = [1,2,3,4]

x.each do |e|
puts e
done

This is NOT syntactic sugar. The list class has a each method that takes a piece of code as an argument and executes it for each element in the list. This can do the same as generators now coming into the new Python and is very similar to higher-order functions in functional languages.
Basically the do...done part is a parameter (albeit a special one, a method may only have one).

It is difficult and syntactiucally tricky to do this in most OO languages and trivial to add an each method (or whatever you want to call it) to your own classes. It is also extremely powerful way of doing many thing which requires a lot of messiness in other languages.

This high-erorder code blocks now allow you to really do the everything-is-anobject thing because you MUST have code blocks to implement control structures such as if or while as an object. It is also very pervasively used in all collections and for instance in REXML where you can say

x = some XML...

x.each( xpath expression ) do |element| ...
done

Another example

String.each_regexp( regexp ) do ... done

Does the code for each place where the regexp was found in the string. Same sort of thing can be done for databases and so forth.

Ruby also has things like mix-in classes which are usually dissed by OO theoreticians but turn out to be very useful. Mix-in classes were pioneered by some dialect of LISP and are a form of restricted multiple inheritance,. A class can inherit methods from other modules but not instance variables (except for its parent class). This allows you to this (this is pseudocode)

myclass inherits Ord
implement = and other operators in terms of and = (which are supplied by your class). And now your class implements all of these methods. This is again tricky to implement in traditional top-down inheritance trees. Think of Java's interface system, but with default implementations.

This is used to great effect in the collections to implement many things in terms of some primitve operators.

Re:Former perl, python, java geek gone to Ruby

[Colonel Panic]

I thought that code blocks were a pretty lame excuse for proper functions-as-data, so I'm a little bit surprised to see them mentioned as a great feature. Did I miss something?

You did.

Code blocks are probably one of the most important features of Ruby that differentiates it from Python.


From what I understand, code blocks are basically anonymous functions that the method they are passed to can only invoke with yield, right?

wrong.

Or is it possible to treat them as any other parameter, i.e. store them, pass them further around, take more than one etc?


Yes. Yes. Yes. Yes (well, that last one is a qualified yes, if I understand your question correctly: you have to convert them to Proc objects before you can pass more than one of them to another method due to the fact that the '&' block delimiter in the method's parameter list can only be on the last parameter - it's not a big limitation).

At first glance, code blocks don't seem that interesting, cool or useful, however, I was able to create a domain-specific hardware description language using them without the need to create any parser for that langauge. It was written in pure Ruby, but to the user it looks like another language in it's own right.

So I could do things like (if you're familiar with VHDL this should look familiar):

process(clk,rst) {
if clk.event and clk == '1'
counter.assign counter + 1
elsif rst == '1'
#do resest:
counter.assign 0
end
}
#

It's all written in pure Ruby. The part between the '{' and '}' is a code block that's being passed to the process method which will execute the block whenever the value of clk or rst changes. So essentially, code blocks allowed me to make Ruby look a lot like VHDL. It looks very natural. AFAIK, this sort of thing is not (easily) doable in Python.

Re:Former perl, python, java geek gone to Ruby

[MarkusQ]

> * Blocks are litteraly a bag hung on the side. Needlessly ugly and limiting.

Why do you feel they are ugly? Ok, they are not real functions like scheme has them, but Ruby wants to be an object oriented language, so it's ok that they are (can be transformed to) objects.

I don't object to blocks being objects; I object to them being arbitrarily forced into a special-syntax-optional-singleton-parameter gheto. Why can't I define a method that takes two or more blocks (e.g. if/then/else) with the same syntax I use for methods that take a single block? Why can't I introspect the structure of a block? Why the duality with Proc objects? In short, why aren't blocks first class objects?

>* The typographic hungarian notation ($ for globals, capitals for constants, etc)

Hungarian notation encodes the type of a variable into the variable name. In Ruby the sigils are used to show the scope of the variables.

Hungarian notation (as the term is generaly used) encodes metadata into the variable name. Type, class, scope, storage class, etc. are all metadata. None of them should be duct-taped on to variable names (IMHO) because it obscures the intent of the code with a clutter of details about the means.

You can see at one glance that @@foo is class variable, @bar is an instance variable and $baz is a global variable. I found this to be very useful while refactoring code.

Sure, and I can imagine cases where it would be handy to have a language require that every variable reference includes a comma seperated list of the line numbers of each reaching assignment. It sure would make it easy to spot uninitialized variables, for example. But in general, it would make the code harder to read and maintain.

More to the point, in ruby I'd like to be able to change the scope or storage class of an object reference without having to rename it.

-- MarkusQ

Re:Former perl, python, java geek gone to Ruby

[ProfKyne]

AFAIK, Python doesn't let you subclass built-in types, and it certainly doesn't let you treat integers as objects.

>>> class IntegerSubclass(int):
... pass
>>> issubclass(IntegerSubclass, int)
1

In summary though, I don't know Python or Ruby well enough to enumerate all the differences between them. I just find that nearly every program I want to write becomes much shorter and easier in Ruby than it was in Python.

Doesn't sound like you've really spent enough time in Python to make that comparison.

Re:Former perl, python, java geek gone to Ruby

[xteddy]

Why can't I define a method that takes two or more blocks (e.g. if/then/else) with the same syntax I use for methods that take a single block? Why can't I introspect the structure of a block? Why the duality with Proc objects? In short, why aren't blocks first class objects?

To clarify this first: It's always possible to create multiple Proc objects with Proc.new, lambda or proc and pass them to a method.

There are two reasons why there are blocks AND Proc objects:

1. To use a block it's not necessary to create an object and that's good for the performance, e. g. if you have to iterate very often over some collection.
2. Blocks are used for iterators and control structures, so Matz wanted them to look like those already did.

It would perhaps be possible to have something like that:

foo { ... } { ... }

But there is an ambiguity because the first block could also be a hash constructor. I am not sure if it would be possible to solve that problem by changing the parser. You could limit yourself to use only do ... end with multiple blocks but I thinks that it's better not to have multiple do ... end blocks in one method call.

BTW: The if/then/else is not a method call and the selectors consist only of a single word in Ruby unlike in Smalltalk. So it would require a big change to the language and the interpreter if blocks should be used there.

Introspection of blocks is a good idea. Perhaps this will be possible if the new VM for Ruby 2.0, called Rite, is implemented. AFAIK it also should be possible to change code in the parse tree on the fly at arbitrary places then.

More to the point, in ruby I'd like to be able to change the scope or storage class of an object reference without having to rename it.

This is clearly a tradeoff. You can choose between having to look up the variables everytime you want to know their scope or between seeing it easily and change every variable if you want to extract a method. I think to choose the latter is a good choice for a language where you don't usually program in a code browser.

Re:Hmmm...

[Guido von Guido]

You know, reading over the the information available for Perl 6, I get the idea that a lot of the improvements intended for Perl 6 were actually stolen from Ruby. As much as I love Perl, the OO implementation is a bolted-on, pain-in-the-ass kludge. Ruby's is an integral part of the language, and Ruby is a very nice language.