Python - Interesting SqlAlchemy Python code
Most of us in private industry have a way easier time coding, than those authoring and maintaining OpenSource and products for use outside of our own engineering teams.
Perhaps you disagree with this sentiment. It is opinion, and a rather broad brush. Rather than the result of some detailed meta-analysis of projects. It has been my experience that a lot of supplementary engineering is put into OpenSource and public projects. Sometimes this draws my critique as it complicates comprehension of problem domains.
You would likely have an issue with a bridge builder, simply taking a specification and trying to make it fit into a different space.
Luckily for us, we have undo buttons to forgive us.
I was trying to build the Kolibri documentation using Python 3.8.
I have never been one to use bleeding edge runtimes outside of virtual environments. I could have rolled back a few versions, and made this someone else problem. I May have done that if I had encountered more problems, or was less comfortable in Python.
The error I saw was as follows
AttributeError: module 'time' has no attribute 'clock'
This was not what interested me. My fix was a single-line edit
if win32 or jython: time_func = time.clock else: time_func = time.time
if win32 or jython: time_func = time.perf_counter else: time_func = time.time
What interested me was how readable that if / else statement was.
So, I located the code for that at the top of the file.
py36 = sys.version_info >= (3, 6) py33 = sys.version_info >= (3, 3) py35 = sys.version_info >= (3, 5) py32 = sys.version_info >= (3, 2) py3k = sys.version_info >= (3, 0) py2k = sys.version_info < (3, 0) py265 = sys.version_info >= (2, 6, 5) jython = sys.platform.startswith('java') pypy = hasattr(sys, 'pypy_version_info') win32 = sys.platform.startswith('win') cpython = not pypy and not jython # TODO: something better for this ?
First, let me say. SQL is an Operating system independent language, as-is Python. I did not expect to see this, even in an ORM, but what a gorgeous, expressive and readable way to express intent.
You will notice that there are even patch version checks. A lesson that even the most dedicated groups, occasionally overlook something that modifies behavior or API.
There is not more to this, other than what a beautiful, simple piece of code this is, and a method applicable to most languages I can think of.
A particularly powerful approach I have seen elsewhere, is dependency injection and service discovery. For micro-changes such as these, it seems a large weapon to wield, but a function, perhaps memoized for recall might look like this.
def semantic_version(major, minor=None, patch=None): if all([ minor, patch, str(minor).isnumeric(), str(patch).isnumeric(), ]): return (major, minor, patch) elif all([ minor, str(minor).isnumeric(), not patch, not str(patch).isnumeric(), ]): return (major, minor) return (major, 0) def version_check(identifier, op=None, minor=None, patch=None): if str(identifier).isnumeric(): # semver version = semantic_version(identifier, minor, patch) sys_version = sys.version_info if op == 'gte': return sys_version >= version elif op == 'lte': return sys_version <= version elif op == 'gt': return sys_version > version elif op == 'lt': return sys_version < version else: return sys_version >= version and not sys_version < version and not sys_version > version else: return bool( identifier and any([ identifier == 'jython' and sys.platform.startswith('java'), identifier == 'pypy' and hasattr(sys, 'pypy_version_info'), identifier == 'win32' and sys.platform.startswith('win'), identifier == 'cython' and not version_check('jython') and not version_check('pypy'), # TODO: something better for this ? ]) )
I hope we can agree that is less elegant, although perhaps as readable, and easily memoized. The one improvement I would make would be to separate into distinct functions.