Re: [RFD/BUG?] git show with tree/commit

[Michael J Gruber <git@drmicha.warpmail.net>]

Michael J Gruber venit, vidit, dixit 13.04.2016 10:02:
> Junio C Hamano venit, vidit, dixit 12.04.2016 18:26:
>> Michael J Gruber <git@drmicha.warpmail.net> writes:
>>
>>> $ git show cab2cdadfda8e8e8631026443b11d3ed6e7ba517:
>>> tree cab2cdadfda8e8e8631026443b11d3ed6e7ba517:
>>>
>>> .gitattributes
>>> .gitignore
>>> .mailmap
>>> ...
>>>
>>> While it's clear to me what's going on, I'm wondering whether it's a
>>> good idea that "git show" says "tree" in front of the unresolved
>>> treeish, whether it's a tree, a commit or something else. I think it's
>>> pretty confusing.
>>
>> There is no "unresolved treeish" on the line that begins with
>> "tree", but I suspect it wasn't very clear to you because of the way
>> you gave the command its input; notice the line in question ends
>> with a colon, which is unfortunate, but it turns out that it is your
>> fault ;-).  Read on.
> 
> Guess what, I know the difference between "git show <commit>" and git
> show <commit>:"...
> 
>>> Alternatives would be:
>>>
>>> tree <resolved tree id> # here: 040...
>>> treeish <treeish>	# here: "treeish cab2c..."
>>> tree <treeish>^{tree} 	# here: "tree cab2c^{tree}"
>>
>> So, the three choices are
>>
>>  (1) resolve the tree object name to 40-hex and show it as
>>      "tree <object name in hex>"
>>
>>  (2) given an object that is not a tree, show it as "treeish <object
>>      name>" 
>>
>>  (3) do not do anything fancy, just show it as "tree <object name>"
>>      using what the user gave us.
> 
> (3) ist not quite what I'm after, but I guess when "git show" receives
> "<commit>:" there is no way it could trace back that tree reference to
> the commit. In fact, (3) is what we have now.
> 
>> I think the current output is doing the third one (notice the colon
>> at the end of the line).
>>
>>     $ git show master: | head -n 1
>>     $ git show master^{tree} | head -n 1
>>     $ git show cab2cdadf: | head -n 1
>>
> 
> I confess that I failed to copy the trailing ":" from the original
> output... So that one is my fault.
> 
> In fact, while specifying "<commit>:" knowingly to show the tree, I
> interpreted the ":" in the output as a simple colon introducing the
> following output, at least at first glance.
> 
> I guess (1) would be the only option that would help (because
> "<commit>:" is a tree, not a non-tree treeish).
> 
> Michael

... adding to that, "git show foo" shows

"commit <sha1 of foo>" for a commit object
"tree <verbatim foo>" for a tree object

nothing like that for tag objects and blobs (just the object contents)

So for 2 out of the 4 object types, it shows a "header line", and both
of them show the specified argument differently (resolved to sha1 resp.
verbatim). It's that inconsistency that I find confusing.

Michael