# -*- coding: utf-8 -*-

from ..syntax import macros, test, the # noqa: F401

from ..test.fixtures import session, testset

from operator import add

from functools import partial

# `Values` is also tested where function composition utilities that use it are.

from ..funutil import call, callwith, Values, valuify

def runtests():

with testset("@call (def as code block)"):

# def as a code block (function overwritten by return value)

@call

def result():

return "hello"

test[result == "hello"]

# use case 1: make temporaries fall out of scope

@call

def x():

a = 2 # many temporaries that help readability...

b = 3 # ...of this calculation, but would just pollute locals...

c = 5 # ...after the block exits

return a * b * c

test[x == 30]

# use case 2: multi-break out of nested loops

@call

def result():

for x in range(10):

for y in range(10):

if x * y == 42:

return (x, y)

... # more code here # pragma: no cover

test[result == (6, 7)]

# can also be used normally

test[the[call(add, 2, 3)] == the[add(2, 3)]]

with testset("@callwith (argument freezer), and pythonic solutions to avoid it"):

# to pass arguments when used as decorator, use @callwith instead

@callwith(3)

def result(x):

return x**2

test[result == 9]

# specialize for given arguments, choose function later

apply23 = callwith(2, 3)

def myadd(a, b):

return a + b

def mymul(a, b):

return a * b

test[apply23(myadd) == 5]

test[apply23(mymul) == 6]

# callwith is not essential; we can do the same pythonically like this:

a = [2, 3]

test[myadd(*a) == 5]

test[mymul(*a) == 6]

# build up the argument list as we go

# - note curry does not help, must use partial; this is because curry

# will happily call "callwith" (and thus terminate the gathering step)

# as soon as it gets at least one argument.

p1 = partial(callwith, 2)

p2 = partial(p1, 3)

p3 = partial(p2, 4)

apply234 = p3() # terminate gathering step by actually calling callwith

def add3(a, b, c):

return a + b + c

def mul3(a, b, c):

return a * b * c

test[apply234(add3) == 9]

test[apply234(mul3) == 24]

# pythonic solution:

a = [2]

a += [3]

a += [4]

test[add3(*a) == 9]

test[mul3(*a) == 24]

# callwith in map, if we want to vary the function instead of the data

m = map(callwith(3), [lambda x: 2 * x,

lambda x: x**2,

lambda x: x**(1 / 2)])

test[tuple(m) == (6, 9, 3**(1 / 2))]

# pythonic solution - use comprehension notation:

m = (f(3) for f in [lambda x: 2 * x,

lambda x: x**2,

lambda x: x**(1 / 2)])

test[tuple(m) == (6, 9, 3**(1 / 2))]

# The `Values` abstraction is used by various parts of `unpythonic` that

# deal with function composition; particularly `curry`, the `compose` and

# `pipe` families, and the `with continuations` macro.

with testset("Values (multiple-return-values, named return values)"):

def f():

return Values(1, 2, 3)

result = f()

test[isinstance(result, Values)]

test[result.rets == (1, 2, 3)]

test[not result.kwrets]

test[result[0] == 1]

test[result[:-1] == (1, 2)]

a, b, c = result # if no kwrets, can be unpacked like a tuple

a, b, c = f()

def g():

return Values(x=3) # named return value

result = g()

test[isinstance(result, Values)]

test[not result.rets]

test[result.kwrets == {"x": 3}] # actually a `frozendict`

test["x" in result] # `in` looks in the named part

test[result["x"] == 3]

test[result.get("x", None) == 3]

test[result.get("y", None) is None]

test[tuple(result.keys()) == ("x",)] # also `values()`, `items()`

def h():

return Values(1, 2, x=3)

result = h()

test[isinstance(result, Values)]

test[result.rets == (1, 2)]

test[result.kwrets == {"x": 3}]

a, b = result.rets # positionals can always be unpacked explicitly

test[result[0] == 1]

test["x" in result]

test[result["x"] == 3]

def silly_but_legal():

return Values(42)

result = silly_but_legal()

test[result.rets[0] == 42]

test[result.ret == 42] # shorthand for single-value case

with testset("valuify (convert tuple as multiple-return-values into Values)"):

@valuify

def f(x, y, z):

return x, y, z

test[isinstance(f(1, 2, 3), Values)]

test[f(1, 2, 3) == Values(1, 2, 3)]

if __name__ == '__main__': # pragma: no cover

with session(__file__):

runtests()