Re: Question about type tags

Oren Ben-Kiki <[email protected]> Tue, 29 Sep 2009 22:32:02 -0700
Newsgroups	gmane.text.yaml.general
Message-ID	<1254288722.5043.37.camel@nero>
On Tue, 2009-09-29 at 10:13 -0700, William Spitzak wrote: 
> Just to follow up, we are using tags.
> 
> A big advantage so far is that the tag is optional and it is easy to 
> ignore it when reading. This allows further compression by omitting the 
> tag when the reader knows the type, which happens a lot, but it is still 
> ok if the writer wrote the tag.
> 
> This proposal:
> 
> >>> - a: { name: nameofa, a: value of a }
> >>> - b: { name: nameofb, b: value of b }
> 
> seems a little strange in that it looks like a list of objects with one 
> member for each type.

It is exactly that: a list of mappings, each with a single key, and a
value which is a mapping with two keys (name and an additional one).

> If the second '-' was not there it would be 
> setting both the 'a' and 'b' members and a yaml validator would think 
> this is ok.

If there was no second '-' it would be a list of objects with one entry;
that entry would be a mapping with two keys.

Both of these are very different from a list containing two entries,
each being a tagged mapping with two keys (name and an additional one).

> I think the description of tag syntax is confused in the YAML 
> documentation. Would prefer that the leading '!' be considered a token 
> indicating a tag and the tag itself be the rest of the string (including 
> any further '!' characters). I believe this matches much more how people 
> use it. For instance I certainly store all my local tags with no '!' in 
> them.

I think you are ascribing some magic to your example syntax that does
not actually occur. Tags are very different from mapping keys.

Have fun,

    Oren Ben-Kiki


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