Passing multiple code blocks as arguments in Ruby
I have a method which takes a code block.
def opportunity
@opportunities += 1
if yield
@performances +=1
end
end
and I call it like this:
opportunity { @some_array.empty? }
But how do I pass it more than one code block so that I could use yield twice, something like this:
def opportunity
if yield_1
@opportunities += 1
end
if yield_2
@performances +=1
end
end
and:
开发者_开发技巧opportunity {@some_other_array.empty?} { @some_array.empty? }
I am aware that this example could be done without yield, but it's just to illustrate.
You can't pass multiple blocks, per se, but you can pass multiple procs or lambdas:
Using 1.9 syntax:
opportunity ->{ @some_array.empty? }, ->{ @some_other_array.empty? }
and in the method itself:
def opportunity(lambda1, lambda2)
if lambda1.()
@opportunities += 1
end
if lambda2.()
@performances += 1
end
end
I'm really late to the Ruby party - just learning it now. And this is an old post, but I just had this question myself so appreciate it being here. I came up with a higher order function possibility, but I couldn't get rid of the dummy variable. So I lived with it.
@opportunities = 0
@performances = 0
def opportunity &b1
method(
def helper b1, dummy, &b2
if b1.call
@opportunities += 1
end
if b2.call
@performances += 1
end
end).curry[b1]
end
opportunity {true}[nil]{true}
p [@opportunities, @performances] #[1, 1]
opportunity {false}[nil]{true}
p [@opportunities, @performances] #[1, 2]
opportunity {false}[nil]{true}
p [@opportunities, @performances] #[1, 3]
opportunity {false}[nil]{false}
p [@opportunities, @performances] #[1, 3]
opportunity {true}[nil]{false}
p [@opportunities, @performances] #[2, 3]
opportunity {true}[nil]{true}
p [@opportunities, @performances] #[3, 4]
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