From: Robert Klemme <bob.news@...>
Date: 2005-12-23T17:37:50+09:00
Subject: Re: correct terminology for a function that yields

Joe Van Dyk wrote:
> On 12/22/05, Edward Faulkner <ef@alum.mit.edu> wrote:
>> On Fri, Dec 23, 2005 at 09:00:31AM +0900, Joe Van Dyk wrote:
>>> def foo
>>>   yield
>>> end
>>>
>>> foo do
>>>   puts "hey"
>>> end
>>>
>>>
>>> What's the correct description of what is going on there?  I've got
>>> a function foo.  No arguments, right?  Does it "take a block"?  I
>>> know it gives control to the block, but I'm not sure of the correct
>>> terminology to use.
>>
>> It does indeed "take a block".  The block argument is implicit.  You
>> could make it explicit if you wanted to:
>>
>> def foo(&blk)
>>     blk.call
>> end

Note, that this has some performance implications though.

>> In more general terms, any function that takes another function as an
>> argument (or returns one as a result) is known as a higher-order
>> function.
>
> Ok, thanks.  I'm writing documentation for a domain-specific language
> (in Ruby) that I created.  People who use it are probably programmers,
> but may not be experienced with Ruby, so I wanted to explain a little
> bit about what's going on behind the scenes.

You can as well call the block "anonymous function" or "anonymous
callback" IMHO.  What I like about the "callback" variant is that it
precisely describes what's happening here: the caller provides a function
as hook that is called by the method.

Kind regards

    robert