Case statement with multiple values in each 'when' block
The best way I can describe what I'm looking for is to show you the failed code I've tried thus far:
case car
when ['honda', 'acura'].include?(car)
# code
when 'toyota' || 'lexus'
# code
end
I've got about 4 or 5 different when situations that should be triggered by approximately 50 different possible values of car . Is there a way to do this with case blocks or should I try a massive if block?
In a case statement, a , is the equivalent of || in an if statement.
case car
when 'toyota', 'lexus'
# code
end
Some other things you can do with a Ruby case statement
You might take advantage of ruby's "splat" or flattening syntax.
This makes overgrown when clauses — you have about 10 values to test per branch if I understand correctly — a little more readable in my opinion. Additionally, you can modify the values to test at runtime. For example:
honda = ['honda', 'acura', 'civic', 'element', 'fit', ...]
toyota = ['toyota', 'lexus', 'tercel', 'rx', 'yaris', ...]
...
if include_concept_cars:
honda += ['ev-ster', 'concept c', 'concept s', ...]
...
case car
when *toyota
# Do something for Toyota cars
when *honda
# Do something for Honda cars
...
end
Another common approach would be to use a hash as a dispatch table, with keys for each value of car and values that are some callable object encapsulating the code you wish to execute.
将数据放入逻辑的另一个好方法是这样的：
# Initialization.
CAR_TYPES = {
foo_type: ['honda', 'acura', 'mercedes'],
bar_type: ['toyota', 'lexus']
# More...
}
@type_for_name = {}
CAR_TYPES.each { |type, names| names.each { |name| @type_for_name[type] = name } }
case @type_for_name[car]
when :foo_type
# do foo things
when :bar_type
# do bar things
end
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