From: Hal Fulton <hal9000@...>
Date: 2004-03-29T20:30:57+09:00
Subject: Re: YAML and initializers

why the lucky stiff wrote:
> Good discussion, Hal.  I've been really rethinking the YAML+Ruby typing 
> mechanism, so this is a perfect time for this.  Right on.

Good, I have some other random thoughts below. Thanks for replying...

> In the case of the above constructor, it would be impossible for YAML to 
> know in what order to pass the three parameters and I don't have any 
> ideas for making the YAML loader work with the constructor.

Right, I was thinking of some heavyweight solution in which we passed
symbols to a YAML.construct or some such. Silliness basically.

> I think the best solution for this would be akin to 
> Object#initialize_copy.  In fact, it seems like YAML could call 
> Object#initialize_copy with the new object, should an 
> Object#initialize_copy method exist.  Yeh?

Very good idea, yes. I see no drawbacks there so far.

Wish I had thought of that. I made do with a #defaults method that did
an ||= on each nil value. Cleaned up #initialize a bit, which now calls
it.

I was seriously thinking of an RCR to allow things like:

   def initialize(@alpha,@beta,@gamma=5)
     # Nothing else needed here
   end

But I think Matz rejected a similar idea 2-3 years ago.

> Yes, you can also do this with a typing callback:

[snip]

Ah, cool, yes.

Other questions...

1. Have you given any thought to preserving comments in  yaml files?
E.g., I read in an entire file, modify some stuff, and write it out
again -- any practical way to keep the comments?

2. I wish for a little more control over formatting. Possible?
    a. Specify order of fields instead of alphabetic
    b. Align field names and data in a "prettyprinted" way


Thanks for all your hard work...


Hal