我经常遇到一堆复杂的 if
语句,Ruby 的清理方法是什么?
(在这个服务对象示例中,一个 foo 有很多条。这是为了将一个条转移到不同的 foo。)
class BarManager
include FancyErrorLogger
def self.transfer(bar, new_foo)
# Is a move needed? Is this line superfluous and a premature optimisation?
return true if bar.foo_id == new_foo.id
# Checks that bar can be moved to new_foo. Many more elsifs in practice, needs refactoring. These examples demonstrate the potential complexity of each step, preventing the use of overly simplistic solutions such as seen here http://codereview.stackexchange.com/questions/14080/avoiding-a-lot-of-ifs-in-ruby
if bar.dependency == :do_not_move_me or bar.some_condition == false
bar.errors.add( :transfer, "This is the bar that can't be moved, it is on street corners moping and singing")
return false
elsif new_foo.want_more_bars == false
bar.errors.add( :transfer, "\"We don't take kindly to your type, bar\" - #{new_foo.name}")
return false
elsif ((bar.baz.optional_external_nightmare_status != :unused) || (new_foo.bars.inject(false){|result, element| result = result || element.baz.optional_external_nightmare_status != :unused}))
bar.errors.add( :transfer, "I have some baz news for you...")
return false
elsif bar.yet_another_failure_reason_there_are_many
bar.errors.add( :transfer, "There are many ways for this to fail, this if statement is somewhat short")
return false
elsif bar.stubborn?
bar.lure_with_carrot!
if bar.munching?
bar.errors.add ( :transfer, "eh, what's up doc" )
return false
elsif !bar.following?
bar.errors.add ( :transfer, "Your carrot is too small and inadequate. No jokes please" )
return false
end
end
# We made it through the gauntlet, now for the transfer
cache_old_foo_id = bar.foo_id # we might need this
bar.foo_id = new_foo.id
bar.save!
# If we are using Rails counter caching:
Foo.increment_counter(:bars_count, new_foo.id)
Foo.decrement_counter(:bars_count, cache_old_foo_id) # we DID need it
return true
rescue Exception => e
fancy_error_log e
false
end
end
最佳答案
第 1 步是从那个长 if
语句中删除重复项。 if
返回一个值(如果没有 if
/elsif
匹配则返回 nil),所以你可以这样做
error =
if bar.dependency == :do_not_move_me or bar.some_condition == false
"This is the bar that can't be moved, it is on street corners moping and singing"
elsif new_foo.want_more_bars == false
"\"We don't take kindly to your type, bar\" - #{new_foo.name}")
elsif ((bar.baz.optional_external_nightmare_status != :unused) || (new_foo.bars.inject(false){|result, element| result = result || element.baz.optional_external_nightmare_status != :unused})
"I have some baz news for you..."
elsif bar.yet_another_failure_reason_there_are_many
"There are many ways for this to fail, this if statement is somewhat short"
elsif bar.stubborn?
bar.lure_with_carrot!
if bar.munching?
"eh, what's up doc"
elsif !bar.following?
"Your carrot is too small and inadequate. No jokes please"
end
end
if error
bar.errors.add :transfer, error
return false
end
第 2 步是将条件提取到名称易于理解的方法中,这在任何情况下都是一个好主意。将每个条件中的所有内容都移动到它的方法中,甚至是 !
运算符,并为每个方法提供相同的参数列表。我们稍后会看到原因。
error =
if bar.unmovable? new_foo
"This is the bar that can't be moved, it is on street corners moping and singing"
elsif bar.unwanted? new_foo
"\"We don't take kindly to your type, bar\" - #{new_foo.name}")
elsif bar.has_bad_news? new_foo
"I have some baz news for you..."
elsif bar.will_fail_for_yet_another_reason? new_foo
"There are many ways for this to fail, this if statement is somewhat short"
elsif bar.lure_with_carrot? new_foo # if you don't like the side effects, lure it before the if
"eh, what's up doc"
elsif bar.uninterested_in_carrot? new_foo
"Your carrot is too small and inadequate. No jokes please"
end
# use error as above
第 3 步是再次删除重复项:
checks = {
unmovable?: "This is the bar that can't be moved, it is on street corners moping and singing",
unwanted?: "\"We don't take kindly to your type, bar\" - #{new_foo.name}"),
has_bad_news?: "I have some baz news for you...",
will_fail_for_yet_another_reason?: "There are many ways for this to fail, this if statement is somewhat short",
lure_with_carrot?: "eh, what's up doc",
uninterested_in_carrot?: "Your carrot is too small and inadequate. No jokes please"
}
method_name, error = checks.find { |method_name, _| bar.send :method_name, new_foo }
# use error as above
关于ruby-on-rails - 如何在 Ruby 中重构长 if/return 语句?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/24450982/