define_method :hash_count do
hash = ''
hash << 'X' while hash.length < 25
hash # returns the hash from the method
end
puts hash
I was expecting
XXXXXXXXXXXXXXXXXXXXXXXX
To be outputted to the screen. Instead I get bizarre random numbers such as
3280471151433993928
and
-1945829393073068570
Could someone please explain? Scoping in Ruby seems way weirder than in PHP/Javascript!
Hello again :) Try this:
def hash_count
hash = ''
hash << 'X' while hash.length < 25
hash # returns the hash from the method
end
puts hash_count
You have called hash, which is the same as self.hash. See the documentation for details about the hash method. Note: hash outside of the method is not the same as hash (the string) within your method, because hash (the string) is defined in the method scope.
Note: You may still use define_method :hash_count do, but from the code I've seen here, a simple def hash_count is more readable.
I see what you expect this. It is a scope problem.
The variable hash already exists both inside and outside of the block as a function call. Whenever you declare a variable or function with the same name you will be shadowing it in that scope - that is, make the older invalid and using your just defined behaviour for that name.
In your case, you declared it in the scope of your block, and so shadowed the Object#hash function as a string variable inside the do/end block. However, the variable was not shadowed outside of your block, and thus kept the original function call.
So, for example
hash = ''
define_method :hash_count do
hash << 'X' while hash.length < 25
hash # returns the hash from the method
end
puts hash
Should work as you expected because you are shadowing the hash in the same scope your are using puts. For similar reasons, if you do
def hash_count
a = ''
a << 'X' while hash.length < 25
a # returns the hash from the method
end
puts a
it should raise an undefined variable error, because it is not defined in this scope.