Ruby’s Most Underused Keyword
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Ruby’s Most Underused Keyword
1–10 of 13 posts
Re: Ruby’s Most Underused Keyword
#2Using redo for tail recursion in Ruby is an interesting idea, similar to Clojure's recur keyword.
Re: Ruby’s Most Underused Keyword
#3My personal up until recently underused keyword was (surprise!) "rescue".
I'm not sure how this has been escaping me since 07, but I had no idea you can apply it at the end of an expression, i.e. when you're facing nasty functions that insist on trhowing exceptions, instead of
begin
value = function_that_throws
value = "default"
you can just write:
value = function_that_throws rescue "default"
Re: Ruby’s Most Underused Keyword
#4My personal up until recently underused keyword was (surprise!) "rescue". I'm not sure how this has been escaping me since 07, but I had no idea you can apply it at the end of an expression, i.e. when you're facing nasty functions that insist on trhowing exceptions, instead of begin value = function_that_throws rescue value = "default" end you can just write: value = function_that_throws rescue "default"
Cool, sure, but blind rescues are as the crow flies to bugs: use them wisely, or use them _why-ly.
Re: Ruby’s Most Underused Keyword
#5My personal up until recently underused keyword was (surprise!) "rescue". I'm not sure how this has been escaping me since 07, but I had no idea you can apply it at the end of an expression, i.e. when you're facing nasty functions that insist on trhowing exceptions, instead of begin value = function_that_throws rescue value = "default" end you can just write: value = function_that_throws rescue "default"
that's along the lines of using or for nil returns.
value = function_that_nils || "default"
I've found it makes code more succinct.
Re: Ruby’s Most Underused Keyword
#6My personal up until recently underused keyword was (surprise!) "rescue". I'm not sure how this has been escaping me since 07, but I had no idea you can apply it at the end of an expression, i.e. when you're facing nasty functions that insist on trhowing exceptions, instead of begin value = function_that_throws rescue value = "default" end you can just write: value = function_that_throws rescue "default"
that's along the lines of using or for nil returns. value = function_that_nils || "default" I've found it makes code more succinct.
Careful here: I've seen plenty of "Rubiomatic" bugs that look like this:
value = function_that_nils or "default"
... which results in nil assignment to value. Accidental confusion between || and 'or' is very common in Ruby world IMO, almost like famous == vs = in C.
Re: Ruby’s Most Underused Keyword
#7Using redo for tail recursion in Ruby is an interesting idea, similar to Clojure's recur keyword.
but ruby doesn't support tail recursion effectively? or is this something new in 1.9. Stack level is not deep enough in 1.8 :P
Re: Ruby’s Most Underused Keyword
#8redo, in the Fibonacci example, is still iterative - it's presented as a third way, when it's just a cruftier way of being iterative. If you remove the cruft of the lambda and the redo, you end up with:
def fib(i)
n, result = 1, 0
while i != -1
i, n, result = i - 1, n + result, n
end
result
end
(Separate to this, the fib routines shown produce incorrect results - my example above maintains this, just for comparison with the original code. fib(10) is 55 not 89 - it's one off in its input.)
Re: Ruby’s Most Underused Keyword
#9Earlier quoted context omitted.
that's along the lines of using or for nil returns. value = function_that_nils || "default" I've found it makes code more succinct.
Careful here: I've seen plenty of "Rubiomatic" bugs that look like this: value = function_that_nils or "default" ... which results in nil assignment to value. Accidental confusion between || and 'or' is very common in Ruby world IMO, almost like famous == vs = in C.
Agreed. I think one is for statements (or) and the other one is for expressions (||), so they have different operational precedence, even though you could use them interchangeably, as long as you knew what got executed first.
Re: Ruby’s Most Underused Keyword
#10redo, in the Fibonacci example, is still iterative - it's presented as a third way, when it's just a cruftier way of being iterative. If you remove the cruft of the lambda and the redo, you end up with: def fib(i) n, result = 1, 0 while i != -1 i, n, result = i - 1, n + result, n end result end Cleaner, faster (by 10% on Ruby 1.8) and shorter, but certainly iterative. (Separate to this, the fib routines shown produce…
You are absolutely right... if you're an interpreter...
From a user's point of view, the redo says "run this block again"; and since the block == the method it's just another way to run acc(). Of course, it's still faking, but I've never claimed anything else :-)