Python-CLU – Common Lightweight Utilities

Install it right now! Download or type: $ pip install -U python-clu

The deal with CLU is, it is a bunch of stuff. Like, a junk drawer… but a junk drawer full of building sets: Legos, Robotix, Capsela – and also magic interfaces that let somehow you plug Legos into Capselas and all that. It’s a la carte: you can use one part of CLU (say the inline testing stuff) and ignore the rest. Or just the exporter, or just the predicates collection. Naturally, these things taste great and also taste great together, too.

CLU started out as a packaged-up and sanely written version of the Python tools I wrote for my REPLs, divided up into a bunch of subordinate packages. It’s grown magnificently since then (if I do say so myself). And if you are wondering if “CLU” is a Tron reference, you are correct. “CLU” stands for “Common Lightweight Utilities” – it started out as an acronym for “Command-Line Utilities” but it has grown useful beyond that scope, indeed.

The subordinate packages are pretty well-divided: clu.config contains things to help with configuration, like config-file loading and saving, and data structures like our famous namespaced keymaps. clu.exporting has the @export decorator, a utility to easily label module members for export by adding them to a modules’ __all__ and __dir__ members, plus other stuff like real-name determination. Which, speaking of which, clu.naming has additional easy functions for dealing with the names of your things and other peoples’, and clu.repr has stuff for easily printing, getting, and specifying an objects’ string representation.

You’ll like clu.abstract if you like building class towers – we have ABCs for all types of things. If you like dicts, check out the aforementioned clu.config.keymap and clu.dicts modules – you’ll find things to build dictionary types, represent them, and deal with them later. clu.dispatch will help you manage subprocesses easily, clu.version is better then semver (I promise), clu.testing is great for inlining some quick unit tests, and clu.scripts and clu.repl are what you want for whatever your REPL environment may be… bpython, ipython, ptpython, and many others I am sure!

So do have a look around. Here’s an abridged breakdown of some things within:

• config: Tons of useful things for dealing with your app’s configuration. These are centered around lexically namespaced dictionaries called “KeyMaps”, which basic examples of which can be found in clu.config.keymap. If your nested data looks like:

  data = {
      'yo' : {
          'dogg' : {
              'i-heard' : {
                  'you-like' : "nested data"
              }
          }
      }
  }

  … and you assign it to a keymap, like e.g. keyed = keymap.Nested(data).flatten(), then you can use keyed like so:

  assert keyed["yo:dogg:i-heard:you-like"] == "nested data"

  … The Flat and Nested classes are cheap to construct and lightweight, and generally act like most dict instances in most of the expected ways. There is also an environment-variable keymap adapter in clu.config.env, which if your app uses environment variables that look like like MYAPP_CONFIG_THINGY, they can be accessed through env.FrozenEnviron(appname='myapp') or env.Environ(appname='myapp') like so:

  appenv = Environ(appname='myapp')
  assert appenv['config:thingy'] == "some value"
  appenv['config:doohickey'] = "a different value" # sets MYAPP_CONFIG_DOOHICKEY
                                                   # in the current env

  … and there are plenty of tools for rolling your own KeyMaps in clu.config: the proxy subpackage has a KeyMap proxy class, ns has utility functions for manipulating namespace strings, keymapview has a class tower for KeyMap key/value/item views, and abc has, as you’d expect, all the abstract base classes upon which our KeyMaps are built, for your perusal and eventual enjoyment.

• constants: Definitions of useful constants, as well as polyfills to allow certain dependencies from the Python standard library to work even when some of their moving parts are missing (i.e. Ye Olde Pythone 2.7, various PyPy implementations, etc).

• all: Herein you will find some verrrrry interesting “meta” functions for CLU. You have the import_all_modules(…) function, which when provided your projects’ base path and appname, will return all the package names therein, whether class-based modules defined through clu.exporting or plain ol’ modules defined by files ending in “.py”, basically. It’s awesome.

  The companion function import_clu_modules(¬) is a shortcut just for everything within CLU, and inline_tests(…) yields an iterator over every CLU module that defines inline tests through clu.testing. These are very useful within CLU; for your own project, write your own functions modeled after these! You can’t go wrong.

• fs: Filesystem-related things. Submodules include:

  • fs.filesystem: classes representing filesystem primitives like Directory, TemporaryDirectory, TemporaryName; a version of tempfile.NamedTemporaryFile that works with or without the leading dot in the provided suffix (a peeve of mine); functions for common filesystem operations like which(…), back_ticks(…), rm_rf(…) (be careful with that one), and so forth.

    • The Directory class is particularly extensive, with methods for Zipfile archiving, searching for importable Python files and others, file-suffix histograms, context-managed working-directory management, walking and reverse-walking, and much more.

  • fs.appdirectories: Started out as a pretty much wholesale duplication of the popular appdirs package^† – but it’s been kitted out with many CLUish things, e.g. clu.fs.filesystem.Directory instances. A solid upgrade in my opinion!

  • fs.misc: a bunch of useful miscellany – noteworthy standouts include regex utility functions for constructing filename regex match or exclusion tests.

  • fs.pypath: functions for safe manipulation of sys.path – enhance(…), remove_paths(…), remove_invalid_paths(), &c.

• importing: a whole class-based-module system! Basically you can do this:

  class Derived(clu.importing.base.Module):
  
      """ I heard you like docstrings """
  
      yo = 'dogg'
  
      @export
      def yodogg(self):
          return "I heard you like"
  
      @export
      def nodogg(self):
          return None
  
      export(yo, name='yo')
  
  from clu.app import Derived as derived # TAKE NOTE!!!
  
  assert isinstance(derived, Module)
  assert derived.yo == 'dogg'
  assert derived.yodogg() == "I heard you like"
  assert derived.nodogg() is None

  … see that? just by subclassing clu.importing.base.Module you can create something instantly importable. Awesome, wouldn’t you say? I would say. We’re working out the best way to create the base Module for your own project (the machinery is there but the semantics are not yet perfect) but do feel free to play around with the stuff in clu.importing.base, and have a look at the implementation in clu.importing.proxy of the “parameterized” ProxyModule (there’s a ChainModuleMap container available in the proxy submodule, too).

• repl and scripts: Tools useful in Python REPL environments. In clu.repl, there’s a while module full of ANSI printing and formatting utilities, many of them as classes, a columnize function for, uh, printing things in columns^†, and a modules submodule focused on printing things about your project’s modules and submodules.

  clu.scripts contains a “repl.py” file, which is meant to be loaded into an interactive interpreter like e.g.:

  $ bpython -i «PATH_TO_CLU»/clu/scripts/repl.py

  … which will set all of CLU up for you to use interactively. N.B. if you have your own script you want to include but stil want to use CLU, you can set the CLU_USER_SCRIPT environment variable to the path to your own script, and our “repl.py” script will pick it up.

  clu.scripts also contains treeline and dictroast, which are CLU’s nascent command-line parsing utilities. They make use of the CLU KeyMap idiom (q.v. note supra) and are being worked on right this very µsecond!

• typespace: Contains a submodule typespace.namespace defining SimpleNamespace (á la Python 3’s types.SimpleNamespace) and a slightly more useful Namespace ancestor class; these are used to furnish a typespace.types namespace that contains everything in the standard-library types module, but with all the typenames shortened so they no longer gratuitously end in “Type”. Like e.g. types.ModuleType is to be found in typespace.types.Module, types.FunctionType is typespace.types.Function, et cetera, ad nauseum, so you can just do from clu.typespace import types to lose the redundant “Type” naming suffix – which I don’t know about you but that annoys me, I mean we all know that these things are types because they are in the fucking types module and don’t need those overly verbose extra four characters there at the end. ALSO, there are additional useful types, from Python’s standard library and common packages, in the types namespace. YOU’RE WELCOME!!

• enums: Furnishes alias(…) – which, spoiler alert, let you create aliases within your enums! Oh yes. Like so:

  from clu.enums import alias
  
  @unique
  class Numbers(Enum):
      ONE = 1
      TWO = 2
      THREE = 3
      UNO = alias(ONE)
      DOS = alias(TWO)
      TRÉS = alias(THREE)
  
  assert Numbers.ONE == Numbers.UNO
  assert Numbers.TWO == Numbers.DOS
  assert Numbers.THREE == Numbers.TRÉS

  … aaaaand BOOM, there you go! The alias members of an enum don’t show up when iterating the enum’s members, so they’re for your convenience. For a fantastic CLUish real-life example, have a look at the clu.repl.ansi module, and the enums it defines – these use a metaclass to line the enum’s standard members up with some predefined class attributes defined in a third-party module; we use alias(…) to provide more obvious lexical aliases of these attributes. Yes!

• dicts: Functions and classes for wrangling dicts (and actually Mapping and MutableMapping descendants in general). There are ABCs for key/value/item views for your own mappings, a much better ChainMap, written from scratch and improving on collections.ChainMap, plus a ChainRepr based on reprlib.Repr, and a whole bunch of fast dict-merging functions.

• exporting: This is kind of the heart of CLU. At the beginning of all internal CLU modules, you’ll find something using the Exporter, like this:

  from clu.exporting import Exporter
  
  exporter = Exporter(path=__file__)
  export = exporter.decorator()

  … which I know, I know, the use of __file__ there is kind of irritating. But that exporter instance is now registered with CLU, and whenever there’s a class or function you want made available outside the module, you can specify it like:

  @export
  def public_function():
      print("I’m so public")
      
  class PrivateAncestor:
      """ I’m more private, don’t play with me """
      
  @export
  class PublicThing(PrivateAncestor):
      """ I’m very public, indeed, and available """

  At the end of the module (but before your CLU tests, q.v. note sub.) you put:

  __all__, __dir__ = exporter.all_and_dir()

  … which makes things clear what is public and what is private to consumers of your code, without messing around with underscore prefixes, which I find coarse, and vulgar. You’re not just labeling things for export, though: clu.exporting has tons of machinery for finding out the “true name” of a thing, be it a class (easy), a function (trickier but still easy), an instance (trickier still), and a module variable (totally very tricky indeed).

  For your own project, at some part in your code, all you have to do is: from clu.exporting import ExporterBase, and then subclass ExporterBase with your app’s name and base path. Like so:

  class Exporter(ExporterBase, basepath="/your/project", appname="MyProject"):
      pass

  … then import your own importer (or call it whatever you want) at the top of your own CLUish modules and instantiate per the example supra. See also clu.scripts.dictroast for other tricks your Exporter instances can perform.

• testing: a handy inline unit-test writing setup. It works fine with coverage and pytest – all you have to do is, after your line assigning __all__ and __dir__ at the end of the module proper, something like:

  def test():
      from clu.testing.utils import inline
  
      @inline.precheck
      def before_everything_else():
  	    """ This function runs once before testing """
          # ...
          
      @inline
      def first_test():
          """ This test does one thing """
          # ...
          
      @inline
      def second_test():
  	    """ This test does another thing """
          # ...
          
      @inline.runif(something == something_else)
      def test_conditionally_run():
  	    """ This test only does something if `something` == `something_else` """
          # ...
          
      @inline.diagnostic
      def apres_testing():
  	    """ This function runs once after testing """
          # ...
          
      return inline.test(100)
  
  if __name__ == '__main__':
      sys.exit(test())

  … running the module (with either python -m yourapp.yourmodule or, say, Nox) will show you each tests’ output. But see that return inline.test(100) line? That integer argument tells the CLU testrunner how many times to run each test (we here like to go a hundred times). You’ll get a report – each test function only prints its output on the first run, the other 99 in this case are muted – that shows you the time totals, which will look like this:

  

  … which the astute will note is the output from a non-CLU module. clu.testing.utils is very easy to integrate, as it doesn’t require any other part of CLU. Look over our noxfile for examples of how to run your inline tests as part of a larger suite.

  … there are other testing support tools in clu.testing.utils, have a look. There’s also a clu.testing.pytest submodule, with some currently-under-development pytest plugins.

• mathematics: the future home for math-related stuff. All there is right now is a clamp(…) function that works with numpy dtypes.

• naming: functions for determining the names of things (even module constants and other random things that generally lack things like __name__ attributes) and for the importing and exporting of things by “qualified names” – for instance, you can use naming.qualified_import(…) to import a class CurveSet from its package instakit.processors.curves by doing:

  CurveSet = qualified_import('instakit.processors.curves.CurveSet')

  … which that may be handier for you than composing and hard-coding an import statement. See also the nameof(…) and moduleof(…) functions, and the utility functions (e.g. qualified_name(…)) and predicates (e.g. isnative(…)). Most of these functions take literally anything for their argument.

• predicates: If clu.exporting is the heart, clu.predicates is all of the eyes, ears, fingers and toes of CLU.

  • Do you want to know if a class is a metaclass? We have an ismetaclass(…) predicate for it, for example.
  • Do you want to get an attribute from something you have, but not sure which attributes this something may have (due to versioning or being passed around, or whatever)? attr(thing, 'one', 'two', default=None) will give you thing.one if that exists, thing.two, if thing.one doesn’t, and None if neither of them are there.
  • But… would you maybe like to get a tuple with all of the one attributes across multiple things? attr_across('one', *things) will do exactly that.
  • Similar to the above, pyattr(…) does like attr(…) except one will be expanded to __one__, and item(…) searches over mapping keys rather than attribute names.

  Sweet, right? These functions, and others in the predicates module, are based on accessor, aquirer, searcher, and collator – abstract functions that can themselves be used. In fact most of clu.predicates is written in the functional style – that is to say they are built successively out of multiple lambda statements. If this is not your taste, everything there has been documented thoroughly for your use and you shouldn’t have to program in this style. But… if you do enjoy a spot of FP, the primitives in the module perhaps will interest you more than the more utilitarian contents.

• sanitizer: functions for cleaning up unicode. Right now there is just a list-based sanitize(…) function that tones down anything with high-value code points to the point where it can be safely ascii-ified.

• typology: This is like clu.predicates but with more predicates, many of which are based on typelists. The module is full of typelists and it uses them extensively in its predicates, via isinstance(…), issubclass(…) and a custom version of same called subclasscheck(…) which tries very hard to work with what you give it (instead of just crapping out with a False return value). You will want to explore this one!

• version: This is basically my take on the semver package, only with improvements. I originally developed it for internal use in some of my Python projects, but it stands on its own. You can construct clu.version.VersionInfo instances using semver primitives amongst other things. The (skeletal) git_version subpackage has a couple of Git-related functions, but what you really want is in read_version – therein you’ll find a read_version_file(…) function that uses the ast module to read one of those __version__.py files I know you have lying around. Yes

• The pytest testsuite: CLU has a full set of pytest-compatible unit tests. In addition to copious module-specific CLU inline tests, you can run this test suite using pytest – or, if you’d like to run all the tests, use the fantastic Nox testrunner (which we use) along with our included noxfile.

… AND MORE!!! There really are a ton of useful things in here and one day I will list them (but not today). Have fun with it!! Download CLU today and explore – if you want a full list of everything CLU exports, install it and list them all in your terminal:

$ pip install -U python-clu
$ python -m clu

… which will give you a giant list that looks like this:

† – the original code for some modules in CLU (e.g. clu.fs.appdirectories, clu.repl.columnize, clu.version.read_version) was vendored in from third-party code. This has all been appropriately licensed and credits are inlined where due. Thanks to all CLU contributors, big and small!