From: Richard Kilmer <rich@...>
Date: 2003-03-19T15:35:41+09:00
Subject: Re: XML too hard (YAML opportunity?)


On Wednesday, March 19, 2003, at 01:02  AM, <jbritt@ruby-doc.org> wrote:

>
>> Now you can store anything in a configuration file,
>> which is liberating.  That something is a boolean, string, integer,
>> array, hash or whatever...YAML deals with for me.  That is really 
>> nice.
>
> But what if you don't want to couple your data to a particular language
> type?
>
> Suppose I write a YAML file to hold, say, groups of name=value pairs.  
> My
> understanding
> is that I have to decide, when designing the data file, whether each 
> group
> is to be a
> hash, or a list, or some other type.  My application code will then be
> expecting to deal
> with data arriving as this type.

Ah...the key is that you do not design the data file...this is an XML 
thing.  The to_yaml method creates the format off your object model.

>
> If, later, I decide that DataTypeFoo was a poor choice and would 
> rather my
> app
> process the data as DataTypeBar, I either have to change the config 
> format
> or have
> an extra step in my app to change the data from one format to another. 
> No?
>
> For example, if I have
>
>  some_num: 23
>
> it's an integer.  If later I decide that floats are better and want 
> change
> my
> code, don't the older data files have to be rewritten?

Actually, what will happen is a Hash will be created with a key 
("some_key") and the value(23).  If you change to floats, the Hash will 
have the key ("some_key") and the value(23.0).  It all depends on your 
use of these objects as to whether this will fail.  But this is the 
same for XML too.  If you have a parser that expects a certain format 
in the value of an attribute like:

some_num="23"

and then do:

some_num="23.0"

you have to update your parser.  If you update it, will it break with 
old files?  How long does your parser read the old format and convert 
to the new?

>
>
>>   Oh, and did I say that YAML files are readable?
>
> You did, but I'm not always seeing that when I read the YAML spec.
>

And XML specs are readable???...I was talking about the YAML content, 
not specification.  The YAML library deals with the spec.  I write Ruby 
code and let it emit and parse it.