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Date: Thu, 29 Aug 2013 23:17:19 -0700 (PDT)
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Subject: Re: Is there a function that applies list of functions to a value?
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Xref: csiph.com comp.lang.python:53279

On Wednesday, August 28, 2013 8:50:53 PM UTC+2, Josh English wrote:
> Reduce tricks are nice, but I prefer clarity sometimes:
>=20
>=20
>=20
> def double(x):
>=20
>     return x*2
>=20
>=20
>=20
> def add3(x):
>=20
>     return x+3
>=20
>=20
>=20
>=20
>=20
> def compose(*funcs):
>=20
>     for func in funcs:
>=20
>         if not callable(func):
>=20
>             raise ValueError('Must pass callable functions')
>=20
>=20
>=20
>     def inner(value):
>=20
>         for func in funcs:
>=20
>             value =3D func(value)
>=20
>         return value
>=20
>=20
>=20
>     return inner
>=20
>=20
>=20
>=20
>=20
> add_then_double =3D compose(add3, double)
>=20
> double_then_add =3D compose(double, add3)
>=20
>=20
>=20
> print add_then_double(1) # prints 8
>=20
> print double_then_add(1) # prints 5


This is my favourite design, simple, clear, straightforward, very pythonic =
imho.  So great that I actually dod not notice it, and wrote it again after=
 you! Imho still, the ValueError you are raising is not that important in t=
his context, it would raise an Error anyway.