Errata for Programming Ruby 1.9 (3rd edition)

#48434: cool book, I really like it

but
roman << code unless count.zero?
seems to be incorrect

count.times { roman << code }
is better, I think

because if I write r = Roman(1)
and r = Roman(2)
I get i
try--Paval Lubkiecki

#48531: (This _might_ be more of suggestion for clarifying the content.)

In the description of the Binding class, the text says:

"The variables, methods, value of self, and possibly an iterator block accessible in this context are all retained."

That sounds like you can access the methods as they were where/when the binding is created, which is not necessarily the case. If the example Demo class were originally defined with a `:hullo_world` method that is modified by re-opening the class definition _after_ setting `b1 = k1.get_binding` (`b1 = ...` is from your example), running `eval 'hullo_world', b1` would use the _new_ definition of :hullo_world.

Or if `:hullo_world` were only added to the class after the binding is created, running `eval 'hullo_world', b1` would still use the new definition of `:hullo_world`.

Does that make sense? ...It's really the scope where the binding is made that is retained and not necessarily all the items available at that point.

Unless I'm misunderstanding everything! Send me a quick email if that's the case so I know?

Thanks!

Scott--Scott Steele

#48659: Hash.[] has an important third form, which is not documented here:

Hash[ [ [key, value], ... ] ] → new_hash

see

www.ruby-doc.org/core-1.9.3/Hash.html#method-c-5B-5D--cabo

#48020: The description of the sleep method says "An argument
of zero causes sleep to sleep forever". And the signature shows 0 as the default value of the argument to sleep. In fact, an argument of 0 causes sleep to sleep for 0 seconds, i.e. not at all. Fortunately the default value of the argument to sleep is nil, which does cause sleep to sleep forever!--Ray Bovet

#48456: The documentation for String#ord states in part "Note that it isn’t quite the inverse of Integer#chr, because the latter does not deal with encodings." However, Integer#chr does take an Encoding argument. So, for example, assuming UTF-8 encoding, "ありがと".ord.chr(Encoding::UTF_8) should == "あ". The argument to chr would be unnecessary if the -U command line option were given.--Brian Ford