a = [] array
b = {} hash
c[:name] hash
d[person] object
e[k] hash k = key
f[i] array i = index
index into array using index index into hash using key v = value at k = key
g.gsub(...) string
h[3] array or index number OR hash key
i.each... array or hash...depends on the context
j.slice() array but you can slice on the key or hash
m = n anything
json.parse = converts data into app applicable to read
lookup: Keys Values Inject => enumerable
inject iterate through the values and then the end returns a value and that value should be operation of all the previous values
a = [42, 37, 17, 11, 3] a.inject (first item is cumulative result, second item is some item in the array) (first iteration: the first variable will always be nil)
a.inject { |sum, i| sum + i }
enumerable works the same on array, hash, etc.
a = ["Kristine", "Lauren", "Ian", "Brian]
a.inject do |all, one|
all + ", #{one}"
end
=> "Kristine, Lauren, Ian Brian"`
number operates on itself
**function (pass something into function, does work, returns value)
class have a thing do work on "itself" and return value
class names should always have a capital letter "Class"
new calls initialize
w/o self = class method (calling on IDEA of "Contact" or "Person" instead of just an "instance"
.self = calling on particular "instance" not the whole idea
attr_accessor` : both attr_reader & attr_writer
# attr_reader(:name)
def name()
return @name
end
#attr_writer(:secret)
def keep_secret=(secret)
@secret = secret
end
to_s == inspect