On Sun, Oct 28, 2018 at 7:26 PM Xiao Yafeng <xyf.x...@gmail.com> wrote:
> I'm curious about what type of $in is on Proc class. `$in` isn't "on `Proc` class". `$in` is a *parameter* of the `.new` *method*. > I mean, if $in is IO::Pipe object As a *parameter* of the `.new` method *declaration* the type of `$in` is not explicitly specified. When a parameter's type is not explicitly specified it defaults to the type `Any`. The type of the corresponding `:in` *argument* in a *call* of the `.new` method is of whatever type you choose to pass. Any ordinary value is a sub-type of `Any` so the method will accept it. For example, `True` and `False` are ordinary values so will be accepted. Besides, just curious, why choose '_' as default it looks strange.... > It's '-', not '_'. '-' is a 50 year old or more unix convention that, when used for a filename or pipe name means, depending on context, the standard input or output handles of a process. cf https://stackoverflow.com/a/8045639/1077672 hth -- raiph
