Re: [Qemu-devel] [PATCH v2 2/2] qapi: Allow setting default values for optional parameters

[Eric Blake]

On 05/06/2014 03:55 AM, Markus Armbruster wrote:

>> Keeping the input file easy to write, and more compact than what
>> introspection will output, is a fine tradeoff in my book (easier to
>> maintain if there is less to type; while still having a well-defined
>> conversion to the formal output form).
> 
> Unlike the other sugared form, this one adds syntax beyond JSON, namely
> in some (but not all) member names, and that makes it a bit harder to
> stomach for me.

JSON has no requirement that a 'name':'value' object limit the 'name'
portion to just valid identifier characters.  But I do see your point
about the fact that we are parsing a sigil of '*' as the first character
of 'name' as sugar.

> 
> Whether it's worthwhile depends on how common the case "optional, no
> default" turns out to be.  Wait and see.

It's already VERY common - every optional variable already uses the
syntax.  The question is rather: how many optional variables will be
rewritten to express a default value, vs. those that can be left alone
because the default value is good enough.  A global search-and-replace
could rewrite the entire file to the new syntax for optional variables,
and we could enforce the new more verbose style going forward, but is
the churn worth it?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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