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From: Michael Selik <michael.selik@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: Method Chaining
Date: Fri, 17 Jun 2016 04:23:57 +0000
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Xref: csiph.com comp.lang.python:110046

On Thu, Jun 16, 2016 at 10:53 PM Lawrence D=E2=80=99Oliveiro <lawrencedo99@=
gmail.com>
wrote:

> Example from <http://default-cube.deviantart.com/art/Truchet-612095093>,
> concisely expressing a complex drawing sequence:
>
>     (g
>         .move_to((p1 + p2a) / 2)
>         .line_to(p1 + (p2 - p1) * frac)
>         .line_to((p1 + p1a) / 2)
>         .stroke()
>         .move_to((p2 + p2a) / 2)
>         .line_to(p2 + (p1 - p2) * frac)
>         .line_to((p2 + p1a) / 2)
>         .stroke()
>     )
>

Wouldn't that look nicer with the ``g`` repeated on every line, no extra
indentation, and no extraneous parentheses?

    g.move_to((p1 + p2a) / 2)
    g.line_to(p1 + (p2 - p1) * frac)
    g.line_to((p1 + p1a) / 2)
    g.stroke()
    g.move_to((p2 + p2a) / 2)
    g.line_to(p2 + (p1 - p2) * frac)
    g.line_to((p2 + p1a) / 2)
    g.stroke()

Sometimes it's hard to know when a function has a side-effect. I appreciate
that these impure functions tend to return None.