In the following code:
def main
someArray.all? { |item| checkSomething(item) }
end
private
def checkSomething(arg)
...
end
How do I shorten the all? statement in order to ged rid of the redundant item variable?
I'm looking for something like someArray.all?(checkSomething) which gives a "wrong number of arguments" error.
You could have a slightly shorter code if checkSomething was a method on your object class. Don't know what it is, so, I'm guessing, you're working with primitives (numbers, strings, etc.). So something like this should work:
class Object
def check_something
# check self
end
end
some_array.all?(&:check_something)
But this is, of course, a horrible, horrible way of going about it. Saving a few keystrokes at the cost of such global pollution - absolutely not worth it. Moreover, even this trick will not be available as soon as you will need to pass additional parameters to the check method.
Besides, the original code is quite readable too.
You could use Object#method and Method#to_proc (i.e. &method) to get rid of the item variable, although it is slower:
def main(array)
array.all?(&method(:check_something))
end
def check_something(arg)
arg.odd?
end
main [1,3,5] #=> true
main [1,3,6] #=> false
method is a non-negligible performance hit. It's up for the OP to decide what's more important :)If checkSomething is an item method (i.e. defined in the class of the 'i' object) you could do symbol to proc...
def main
someArray.all?(&:checkSomething)
end
A method only has access to passed arguments, or to selfso to bypass passing arguments you need to make the method an instance method of the object class (so it can use self)
The way you have it... where checkSomething is external to the i class... you can't do that.
Considering you want to keep your object's checkSomething private, I think this would be a good work around :
class Something
def main
someArray.all?(&checkSomething)
end
private
def checkSomething
->(item) do
# Checking part.
end
end
end
For block that executes a method with arguments, Checkout this way...
def main
someArray.all? &checkSomething(arg1, arg2, ...)
end
private
def checkSomething(arg1, arg2, ...)
Proc.new { |item| ..... }
end
could you not use a Ruby's collection method 'any?' instead?
def main
#students is an array of students
students.any?(&:passed)
end
class Student
def passed
#code to check if student passed
end
end
Ref http://ruby-doc.org/core-2.2.2/Enumerable.html#method-i-any-3F
all? and any? have the same constraint here... if you're using symbol-to-proc the method has to be a Student object method (as you did). Your answer would work with all? as well as any? so from that perspective there's no difference.
itemvariable?#all?.. as it doesn't take any parameter as argument.. You have to go with block ..checkSomethingwithout any argument insomeArray.all?(checkSomething), that's why it complains.to_procshortcut (for example,ary.map(&:to_s)) does not apply here.