exbert-project/exbert

1"""General programming utils, inclined toward functional programming.2 3If ever a function changes its input in place, it is denoted by a trailing `_`4"""5 6import inspect7from itertools import zip_longest8from typing import List, Set, Union, Dict9 10 11def ifnone(*xs):12    """Return the first item in 'x' that is not None"""13    for x in xs: 14        if x is not None: return x15    return None16 17def custom_dir(c, add): return dir(type(c)) + list(c.__dict__.keys()) + add18 19class GetAttr:20    """Base class for attr accesses in `self._xtra` passed down to `self.default`21    22    Taken from article by Jeremy Howard: https://www.fast.ai/2019/08/06/delegation/23 24    Usage:25 26        ```27        class ProductPage(GetAttr):28            def __init__(self, page, price, cost):29                self.page,self.price,self.cost = page,price,cost30                self.default = page31        ```32    """33    @property34    def _xtra(self): return [o for o in dir(self.default) if not o.startswith('_')]35    def __getattr__(self,k):36        if k in self._xtra: return getattr(self.default, k)37        raise AttributeError(k)38    def __dir__(self): return custom_dir(self, self._xtra)39 40# Can i delegate many different functions?41# Can i add a new docstring to the existing docstring of the delgated function? Or at least point to the function delegated?42def delegates(to=None, keep=False):43    """ Decorator: replace `**kwargs` in signature with params from `to`.44    45    Taken from article by Jeremy Howard: https://www.fast.ai/2019/08/06/delegation/46    """47    48    def _f(f):49        if to is None: to_f,from_f = f.__base__.__init__,f.__init__50        else:          to_f,from_f = to,f51        sig = inspect.signature(from_f)52        sigd = dict(sig.parameters)53        k = sigd.pop('kwargs')54        s2 = {k:v for k,v in inspect.signature(to_f).parameters.items()55              if v.default != inspect.Parameter.empty and k not in sigd}56        sigd.update(s2)57        if keep: sigd['kwargs'] = k58        from_f.__signature__ = sig.replace(parameters=sigd.values())59        return f60    return _f61 62def pick(keys:Union[List, Set], obj:Dict) -> Dict:63    """ Return a NEW object containing `keys` from the original `obj` """64    return {k: obj[k] for k in keys}65 66def memoize(f):67    """Memoize a function.68    69    Use lookup table when the same inputs are passed to the function instead of running that function again70    """71    memo = {}72    def helper(*x):73        if x not in memo:            74            memo[x] = f(*x)75        return memo[x]76    return helper77 78def assoc(k, v, orig):79    """Given an original dictionary orig, return a cloned dictionary with `k` set to `v`"""80    out = orig.copy()81    out[k] = v82    return out83 84def make_unique(f):85    """The input function will only run and return if it hasn't seen its argument before. 86    87    Otherwise, it will return `None`.88    """89    s = set()90    def helper(x):91        if x in s:92            return None93        s.add(x)94        return f(x)95 96    return helper97 98def flatten_(items, seqtypes=(list, tuple)):99    """Flattten an arbitrarily nested list IN PLACE"""100    for i, x in enumerate(items):101        while i < len(items) and isinstance(items[i], seqtypes):102            items[i:i+1] = items[i]103    return items