patshaughnessy / ruby-under-a-microscope Goto Github PK

page 10

• Next in Chapter 2, How Ruby Executes Your Code, I pick up the story from where Chapter 1 left off and describe how Ruby’s virtual machine, called “Yet Another Virtual Machine” (YARV) executes your program.

page 44

• With Ruby 1.9, the Ruby core team introduced something called “Yet Another Ruby Virtual Machine” (or YARV), which actually executes your Ruby code.

Final paragraph

• Function and method calls are very important and very common in Ruby programs; the Ruby compiles them for YARV using this pattern:

This second stack represents the path through your Ruby program YARV has taken and
it’s current location.

should be =>

This second stack represents the path through your Ruby program YARV has taken and
its current location

I save it in code_value

Should be =>

I save it in function_value

Specifically, this allows the puts statement to access the str2 variable from the parent scope.

Should be =>

Specifically, this allows the puts statement to access the str variable from the parent scope.

Lexical scope refers to the class or module the you are currently defining methods for.

that

I am not sure whether this is appropriate or not. But here is my thought about this sentence on page 128 -

Whenever the FIXNUM_FLAG is set, Ruby knows this VALUE is really a small integer, an
instance of the Fixnum class, and not a pointer to a value structure.

Could it be considered to be rephrased to below sentence for more clarity ?

Whenever the FIXNUM_FLAG is set, Ruby knows this VALUE is really a small integer, an
instance of the Fixnum class, and not a pointer to its corresponding C structure.

Thanks !

Final paragraph

• They may have done this for performance reasons, or because Ruby’s tokenization rules required special logic Lex could’t provide.

The works the same way

This

by using something called a “catch table” A catch table

“catch table”. A

But alongside YARV’s internal stack Ruby also keeps track of your Ruby program’s call stack: which methods called which other methods, functions, blocks, lambdas, etc. In fact, YARV is not just a stack machine – it’s a “double stack machine!” It not only has to track the arguments and return values for it’s own internal instructions; it has to do it for your Ruby arguments and return values as well.

Pat Shaughnessy. Ruby Under a Microscope (Kindle Locations 1079-1082).

Should the first sentence read: "alongside YARV's internal stack YARV also keeps track of your Ruby's program's call stack", or am I misreading?

On page 129 for this line -

The class method returns the class pointer.

Please correct the last font i.e. 's' to match with the entire 'class' word.

Thanks !

It not only has to track the arguments and return values for it’s own internal instructions

Should be =>

It not only has to track the arguments and return values for its own internal instructions

Thanks

look in the org.jruby.compile package

org.jruby.compiler

Tokenization and parsing are two separate processes that actually happen at the time time should be Tokenization and parsing are two separate processes that actually happen at the same time

Just like Ruby itself, YARV has it own control structures

its

Here the puts function call refers equally well to the str variable located inside the
block and the str2 variable from the surrounding code.

Should be ->

Here the puts function call refers equally well to the str2 variable located inside the
block and the str variable from the surrounding code.