From: Daniel Waite <rabbitblue@...>
Date: 2008-04-18T08:58:04+09:00
Subject: Re: When are lambdas needed?

Joel VanderWerf wrote:
> If the latter, then one answer is: when you need the program state that
> is encapsulated in a block to persist outside of the method in which it
> is used. For example, this happens in event-based frameworks: a setup
> method in a client class registers lambdas as event handlers; the
> framework doesn't need to know the classes or methods of the client
> class, hence loose coupling. As a bonus, these handlers can refer to
> shared program state (local variables) in the setup method.

That's probably the clearest illustration I've ever read of when to use 
a block. Thank you.

I hope others chime in, too, as I couldn't imagine programming without 
the "implicit usage" of blocks (e.g. each, select, collect, etc.) but 
have never used them for the purpose Joel described.

I just got "done" designing a delivery system, and although I'm happy 
with it, I wonder if it could be done with blocks. (I re-read that 
statement and it sounds stupid: 'done with blocks'. I'll simply trust 
you see the absurdity of the statement and understand what I was trying 
to say...)
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