4:45 p.m.
----- Original Message -----
From: "Adam Litke" <agl(a)us.ibm.com>
To: "Saggi Mizrahi" <smizrahi(a)redhat.com>
Cc: vdsm-devel(a)lists.fedorahosted.org, "Vinzenz Feenstra"
<vfeenstr(a)redhat.com>
Sent: Monday, January 14, 2013 5:21:41 PM
Subject: Re: [vdsm] API Documentation & Since tag
On Mon, Jan 14, 2013 at 12:37:57PM -0500, Saggi Mizrahi wrote:
>
>
> ----- Original Message -----
> > From: "Adam Litke" <agl(a)us.ibm.com>
> > To: "Vinzenz Feenstra" <vfeenstr(a)redhat.com>
> > Cc: vdsm-devel(a)lists.fedorahosted.org
> > Sent: Friday, January 11, 2013 9:03:19 AM
> > Subject: Re: [vdsm] API Documentation & Since tag
> >
> > On Fri, Jan 11, 2013 at 10:19:45AM +0100, Vinzenz Feenstra wrote:
> > > Hi everyone,
> > >
> > > We are currently documenting the API in vdsmapi-schema.json
> > > I noticed that we have there documented when a certain element
> > > newly
> > > is introduced using the 'Since' tag.
> > > However I also noticed that we are not documenting when a field
> > > was
> > > newly added, nor do we update the 'since' tag.
> > >
> > > We should start documenting in what version we've introduced a
> > > field.
> > > A suggestion by saggi was to add to the comment for example:
> > > @since: 4.10.3
> > >
> > > What is your point of view on this?
> >
> > I do think it's a good idea to add this information. How about
> > supporting
> > multiple Since lines in the comment like the following made up
> > example:
> >
> > ##
> > # @FenceNodePowerStatus:
> > #
> > # Indicates the power state of a remote host.
> > #
> > # @on: The remote host is powered on
> > #
> > # @off: The remote host is powered off
> > #
> > # @unknown: The power status is not known
> > #
> > # @sentient: The host is alive and powered by its own metabolism
> > #
> > # Since: 4.10.0 - @FenceNodePowerStatus
> > # Since: 10.2.0 - @sentient
> > ##
> I don't like the fact that both lines don't point to the same type
> of token.
> I also don't like that it's a repeat of the type names and field
> names.
>
> I prefer Vinzenz original suggestion (on IRC) of moving the "Since"
> token up and then
> have it be a state. It also makes discerning what entities you can
> use up to a
> certain version easier if you make sure to keep them sorted.
>
> We can do this because the order of the fields and availability is
> undetermined (unlike real structs).
That is not correct. These structures are parsed into an OrderedDict
and the
ordering is important (especially for languages like C which might
use real
structs).
The "wire" format, json, ignores the ordering, further more,
for
languages like C we can't use actual structs because then we have
to bump a major version every time we add a field as the
sizeof(struct Foo) changed.
>
> ##
> # @FenceNodePowerStatus:
> #
> # Indicates the power state of a remote host.
> #
> # Since: 4.10.0
> #
> # @on: The remote host is powered on
> #
> # @off: The remote host is powered off
> #
> # @unknown: The power status is not known
> #
> # Since: 10.2.0
> #
> # @sentient: The host is alive and powered by its own metabolism
> #
> ##
>
> The problem though is that it makes since a property of the fields
> and not of
> the struct. This isn't that much of a problem as we can assume the
> earliest
> version is the time when the struct was introduced.
I don't like this any better than my suggestion. Aside from the fact
that field
ordering is important (in the data structure itself), this spreads
the since
information throughout the comment rather than concentrating it in a
single
place.
Well, thinking about it, I don't understand why structs need to have a
"Since" property anyway. Only verbs should have it. Structs are
available (by inference) since the earliest call that produces them.
All fields in a struct are optional anyway. Old versions wouldn't try
and access them, new clients should always assume these fields may
not be returned anyway.
--
Adam Litke <agl(a)us.ibm.com>
IBM Linux Technology Center