Two-Dimensional Expression Layout

[Lawrence D’Oliveiro]

It is handy to be able to keep complex expressions together sometimes, when breaking them up would simply obscure their structure. To avoid lines getting long, why not take advantage of the two available screen/page dimensions to make their structure clearer? As a bonus, spacing out parentheses makes them look less of a clutter.

Examples from <https://github.com/ldo/qahirah_examples/blob/master/operators>:

A function call with complex arguments (specifying arguments by keywords is highly recommended here):

    rect_1_pattern = \
        qah.Pattern.create_linear \
          (
            p0 = (0, 0),
            p1 = (major_dim, 0),
            colour_stops =
                (
                    (0, rect_1_colour),
                    (1, complement(rect_1_colour)),
                )
          )

Computing a variable value (using redundant parentheses to avoid backslash-continuations):

    dest_rect = \
        (
            draw_bounds
        +
            Vector(col, row) * draw_bounds.dimensions
        +
            Vector(0, top_extra)
        )

>From <https://github.com/ldo/python_pixman/blob/master/pixman.py>, a complex condition (with redundant parentheses again):

    if (
            not isinstance(src, Image)
        or
            mask != None and not isinstance(mask, Image)
        or
            not isinstance(dest, Image)
    ) :
        raise TypeError("image args must be Image objects")
    #end if