On Thu, Feb 14, 2013 at 9:31 PM, RKA <[email protected]> wrote:
> Lambda functions are used when you want to call a function that doesn't
> necessarily need a name.
I would put it differently: lambdas are used when you need to use a
function as an object which can be referenced and passed around.
> For example, the each method of the array object
> iterates through all the items in the array and if you want to execute the
> same method over and over again with a different argument you can use a
> lambda function, instead of having to define a function first.
That is probably not such a good example because #each already uses a
different mechanism by using the block passed to the call. Typically
one would do
array.each do |x|
# logic 1
end
array.each do |x|
# logic 2
end
lambdas are really most useful if you store them somewhere for later
execution. This example is not brilliant but I hope it demonstrates
the point:
irb(main):001:0> Calculator = Struct.new :function do
irb(main):002:1* def apply(x, y) function[x, y] end
irb(main):003:1> end
=> Calculator
irb(main):004:0> c = Calculator.new lambda {|a,b| a*b}
=> #<struct Calculator function=#<Proc:0x8003b698@(irb):4 (lambda)>>
irb(main):005:0> c.apply(2, 4)
=> 8
irb(main):006:0> c.apply(4, -3)
=> -12
Kind regards
robert
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