Easiest way to convert an array of strings to a splattable tuple?

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1

Hello, I’m writing a small command-line based crystal program but I’ve run into a small problem. After parsing some command line options using OptionParser I want to call a method that takes a variable number of parameters:

my_args = ["my", "args", "from", "command", "line"]

def my_meth(*args : String)
    # do stuff with args
end

Coming from ruby, I kind of expected the array to be “splattable”, but reading the docs it seems like only a Tuple can be “splatted”. But I cannot find a simple way to convert my array to a tuple. There probably is a simple solution, but I can’t find it in the standard library docs or the crystal book.

Any suggestions on how to solve this problem?

Kind regards

Lars

2

If the array of args is dynamically sized, then you just cannot do it. Maybe update your method signature to be like args : Enumerable(String) and just pass the array directly?

If the size of the array is known at compile time, you could leverage Tuple(*T) - Crystal 1.9.2, but I don’t think that’ll be the case here.

3

Thank you for the quick answer.

Since I’m getting the arguments from the command line I have no control over how many arguments I get, At the same time I don’t want to force callers of the method to wrap a single string in an array. If an array cannot be splatted and it is impossible to convert the array to a tuple it is probably just easier to overload the function.

def my_meth(arg : String)
    my_meth([arg])
end

def my_meth(args : Enumerable(String))
    # Do stuff with args
end

Lars

4

Yes, you could also support both of your use cases via like:

def foo(*args : String)
  foo args
end

def foo(args : Enumerable(String))
    # Do stuff with args
end

Such that you could do:

foo "blah"
foo "bar", "baz"
foo({"a", "b", "c"})
foo(["a", "b", "c"])
foo(some_iterator)
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