I saw the following in a book.
def deleted_roles=(values)
roles.find(*values).each(&:destroy)
end
I understand that this method finds all the roles with the given ids and
calls destroy on all of them. My question is, what is the significance
of *. Why is it roles.find(*values) and not just plain
roles.find(values)?
Is there any difference?
Could it possibly be a typo and the method should be defined as
def deleted_roles(*values)…
Thanks
- expands an array as multiple arguments. For example, type in an irb
session:
def find(*args) # This * is not the same * as yours, this is just used
to collect all the arguments in a single array
args.each {|x| puts x.class}
end
find [1,2,3] => Array
find *[1,2,3] => Fixnum three times.
Regards,
Serabe
Hi,
Is there any difference?
Could it possibly be a typo and the method should be defined as
def deleted_roles(*values)…
It looks like roles.find expects a list of parameters (i.e. it should
be invoked like this: roles.find(‘admin’, ‘user’, ‘editor’))
but deleted_roles= wants an array (i.e. deleted_rows = [‘admin’,
‘user’, ‘editor’])
The * a.k.a. splat does exactly this conversion - so if someone calls
deleted_rows = [‘admin’, ‘user’, ‘editor’]
inside the method
roles.find(‘admin’, ‘user’, ‘editor’).each(&:destroy)
will be called (note that the brackets are gone)
HTH,
Peter
http://www.rubyrailways.com