On 09/04/2013 05:27 PM, Junio C Hamano wrote:
> I am not saying the above is the best format, but the point is that
> the mode of the operation defines the structure
Great, thanks for your comments. Based on that I've prototyped a
new format. Rather than jumping straight to the patch, here is my
proposed format documentation for review:
-------------------------------------------------------------------------
With `--stdin`, update-ref reads instructions from standard input and
performs all modifications together. Specify commands of the form:
create SP <ref> SP <newvalue> LF
update SP <ref> SP <newvalue> [SP <oldvalue>] LF
delete SP <ref> [SP <oldvalue>] LF
verify SP <ref> [SP <oldvalue>] LF
option SP <opt> LF
Quote fields containing whitespace as if they were strings in C source
code. Alternatively, use `-z` to specify commands without quoting:
create SP <ref> NUL <newvalue> NUL
update SP <ref> NUL <newvalue> NUL [<oldvalue>] NUL
delete SP <ref> NUL [<oldvalue>] NUL
verify SP <ref> NUL [<oldvalue>] NUL
option SP <opt> NUL
Lines of any other format or a repeated <ref> produce an error.
Command meanings are:
create::
Create <ref> with <newvalue> only if it does not exist.
update::
Update <ref> to be <newvalue>, verifying <oldvalue> if given.
Specify a zero <newvalue> to delete a ref and/or a zero
<oldvalue> to make sure that a ref does not exist.
delete::
Delete <ref>, verifying <oldvalue> if given.
verify::
Verify <ref> against <oldvalue> but do not change it. If
<oldvalue> zero or missing, the ref must not exist.
option::
Specify an option to take effect for following commands.
Valid options are `deref` and `no-deref` to specify whether
to dereference symbolic refs.
Use 40 "0" or the empty string to specify a zero value, except that
with `-z` an empty <oldvalue> is considered missing.
If all <ref>s can be locked with matching <oldvalue>s
simultaneously, all modifications are performed. Otherwise, no
modifications are performed. Note that while each individual
<ref> is updated or deleted atomically, a concurrent reader may
still see a subset of the modifications.
-------------------------------------------------------------------------
Thanks,
-Brad
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