Ruby anti-patterns

patterns.rb

# For loop
# suggested: replace with each
for i in x
end

# each_with_object mutates array
# suggested: replace with map
each_with_object([]) |list, i|
  list << i
end

# array set by index
array = []
array[2] = 'foo'

# multiple return statements
return true if foo
return true if bar

# calling methods in initialize
# suggested: create a constructor to process the arg before initializing
def initialize(arg)
  @arg = process_arg(arg)
end

# next in iter
# suggested: use select/reject to filter collection before iterating
each do |i|
  next if i == "bar"
end

# type sniffing
# suggested: interface
foo.is_a?(Bar)
foo.kind_of?(Bar)

# hash ||= for initial value
# suggested: override hash constructor
foo[bar] ||= 0
foo[bar] += 1

# ternary returns true or false when invoking boolean operation
# suggested: ternary is not necessary
foo == bar ? true : false

# Array#delete
# suggested: select/reject
foo.each do |i|
  foo.delete(i) if bar
end

# variable reassignment
# suggested: control flow (if/case)
result ||= 'foo' if bar
result ||= 'bar' if foo
result = 'baz' unless result

# setting instance variables outside of setters/initialize
def foo
  @bar = rand(25)
end

# duplicate return values
# suggested: combine statements with a boolean or
if foo
  return 'foo'
elsif bar
  return 'foo'
else
  return 'bar'
end

# boolean parameters
def foo(should_do_something=false)
  do_something if should_do_something
end

# string concatenation
# suggested: use Array#join
time = day + hour + ":" + min

# inject/reduce: mutate and return memo
# suggested: use each_with_object instead
foo.inject([]) do |m, i|
  m << i
  m
end