revision num print out by __repr__

[ke-zhang-rd]

https://github.com/danielballan/amostra/blob/first-pass/amostra/objects.py#L44

I feel user may want to see revision num when then dolist(sample.revisions())

[danielballan]

I think this is worth considering. But let me explain my reasoning for leaving it out so we can weigh our options. Many Python objects have __repr__s that, if you type them out, create an identical object. Examples include lists, dicts, and Counters:

>>> a = [1, 2, 3]
>>> a
[1, 2, 3]
>>> b = {'thing': 'stuff'}
>>> b
{'thing': 'stuff'}
>>> import collections
>>> c = collections.Counter({'a': 1, 'b': 2, 'c': 2})
>>> c
Counter({'b': 2, 'c': 2, 'a': 1})

This has called an "eval-able repr" because eval(repr(obj)) == obj. Obeying this pattern is not a requirement. There are plenty of objects in Python that don't follow it, but it's nice to abide by it where practical. Currently, we do abide by this pattern (after a fashion) with Sample:

>>> client.new_sample(name='...')
Sample(name='...')

If we include any of the read-only traits in the __repr__ output, then we'll be showing something that the user isn't allowed to specify. That is, if the user sees

>>> Sample(name='...', revision=...)

and then, mirroring the pattern above, tries to type:

>>> sample = client.new_sample(name='...', revision=...)

an error will be raised, because the revision of a new Sample is always 0 and is not a parameter.

On the other hand, it's handy to see the revision number in the output. I think we should probably include it and break the pattern. What do you think, @ke-zhang-rd? Any thoughts, @DanOlds, @EliotGann?

[EliotGann]

Breaking the pattern seems like what I would expect. If you can communicate read-only or system-controlled properties in a different way it would make sense to me. (UID is one that shouldn't be changed, I think)

[ke-zhang-rd]

I see your point @danielballan. We may need break pattern.
User may expect a connection(mapping) between sample's actual info(IUCr_chemical_formula='', composition='', description='')and revision. I feel printing them together is a intuitive way to show this mapping.