Passing variable arguments to function

Question

I've set a function with variable arguments:

myfunc: (cmd, args...)->
    # cmd is a string
    # args is an array

And can be called like:

myfunc("one") # cmd = "one", args = undefined
myfunc("one","two") # cmd = "one", args = ["two"]
# etc...

Now, what if I want to call it with unknown number of arguments? Let's say I want to pass an array of args instead of arg1, arg2, arg3,.. how is that possible?

Trying myfunc("one",["two","three"]) or myfunc("one",someArgs) leads to the unfortunate:

# cmd = "one"
# args = [ ["two","three"] ];

Ideas?

P.S. I made it this to work by adding these ultra-simple lines in my function. But is there no other way?

if args? and args[0] instanceof Array
    args = args[0]

mu is too short · Accepted Answer · 2014-11-08 19:04:20Z

3

You don't need to manually use Function.prototype.apply for this. Splats can be used in an argument to list to build an array or in a function call to expand an array; from the fine manual:

Splats...

[...] CoffeeScript provides splats ..., both for function definition as well as invocation, making variable numbers of arguments a little bit more palatable.
awardMedals = (first, second, others...) ->
  #...

contenders = [
  #...
]

awardMedals contenders...

So you can say things like this:

f('one')

f('one', 'two')

f('one', ['two', 'three']...)
# same as f('one', 'two', 'three')

args = ['where', 'is', 'pancakes', 'house?']
f(args...)
# same as f('where', 'is', 'pancakes', 'house?')

and The Right Thing will happen.

Demo: http://jsfiddle.net/ambiguous/ztesehsj/

answered Nov 8, 2014 at 19:04

mu is too short

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TimWolla · Accepted Answer · 2014-11-08 13:01:38Z

1

Use Function.apply:

myfunc.apply @, [ "one", "two", "three" ]

Demo on CoffeeScript.org

answered Nov 8, 2014 at 13:01

TimWolla

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