From: Gavin Sinclair <gsinclair@...>
Date: 2003-12-11T12:29:18+09:00
Subject: Re: Adjusting the Scope of Blocks

[D. Black, ruthlessly snipped:]
>
>   obj.instance_eval { stuff }
>
> where it's all visible and lexically scoped together, doesn't bug me at
> all.  It only starts feeling "trick"-like when the fact that the block
> is going to be instance_eval'd in obj's self context isn't
> manifest.

I agree with everything you wrote, David.  But taking a step back, I'm
inclined to judge that when you pass a block to a method, you have some
idea what the method will do to it.  "Iterator" and "transactional" blocks
are pretty obvious.  "Event-handlers" are pretty cool, too, and it's easy
to understand what they do (execute the block later).

If a method is going to instance-eval or class-eval a block, then it's an
unusual method (not in a common class of methods).  Eval-ing is good for
low-level infrastructure implementation more so than run-of-the-mill data
processing.  Methods that use ?_eval are likely to be "special",
implementing unusual or tricky (but useful) concepts.  Their documentation
should therefore indicate what the user of the method can expect.

Gavin