Re: [Qemu-devel] [PATCH V7 4/6] qemu-img: add -l for snapshot in convert

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

于 2013/12/13 21:44, Eric Blake 写道:
> On 12/08/2013 08:43 PM, Wenchao Xia wrote:
>>>>
>>>> convert -s snapshot.name=name1
>>>>
>>>     Previous I planned to use -l for internal snapshot in all possible
>>> program, since -s is taken as external snapshot in qemu, qemu-nbd.
>
> Consistency in command line options between different tools is nice, but
> is less important than adding functionality.  I'm perfectly fine if we
> use -l in one tool and -s in another, as long as the documentation is
> clear on how to spell the option for the tool I want to use.
>
>>> let -s stands for internal in qemu-img convert only, may bring
>>> confuse to user, so I deprecated it instead of enhance it(I want
>>> to remove it but may bring compatiablity issue).
>>>     Yes, it should report error when both specified, will send a patch
>>> if you agree '-l' should still be used.
>>>
>>>
>>    Eric, I hope to get your idea before patching, any comments?
>>
>
> My biggest concern was that by adding -l as a superset of -s, but not
> taking care of the relation between the two, you created odd command
> line usage patterns.  For qemu-img, it may be simpler to just make -s do
> everything, instead of trying to deprecate it (that is, adding -l for
> consistency with other tools while breaking -s isn't nice).
>
   OK, there is still one cornor case to consider:
-s snapshot.name=name1
   It may change the semantics if a caller used qemu-img convert as
above before, although it seems insane.:)