Feature #12115
Updated by felixbuenemann (Felix Bünemann) over 8 years ago
I am a great fan of the `Symbol#to_proc` shorthand when mapping or reducing collections:
```ruby
[1,2,16].map(&:to_s)
=> ["1", "2", "16"]
[1,2,16].reduce(&:*)
=> 32
```
I often wish it would be possible to pass an argument to the method when doing this, which currently requires a block and is more verbose:
```ruby
[1,2,16].map { |n| n.to_s(16) }
=> ["1", "2", "10"]
# active_support example
{id: 1, parent_id: nil}.as_json.transform_keys { |k| k.camelize :lower }.to_json
=> '{"id":1,"parentId":null}'
```
It would be much shorter, if ruby allowed this:
```ruby
[1,2,16].map(&:to_s.(16))
=> ["1", "2", "10"]
# active_support example
{id: 1, parent_id: nil}.as_json.transform_keys(&:camelize.(:lower)).to_json
=> '{"id":1,"parentId":null}'
```
This can be implemented easily, by adding the `Symbol#call` method:
```ruby
class Symbol
def call(*args, **kwargs, &block)
->(caller, *rest) { caller.send(self, *rest, *args, **kwargs, &block) }
end
end
```
*Source*: [stackoverflow: Can you supply arguments to the map(&:method) syntax in Ruby?](http://stackoverflow.com/questions/23695653/can-you-supply-arguments-to-the-mapmethod-syntax-in-ruby) (and adapted for kwargs)
**I think this is a rather common use case, so I propose to add `Symbol#call` to the Ruby standard library.**