Two-Dimensional Expression Layout

[Lawrence D’Oliveiro]

On Sunday, August 21, 2016 at 12:48:46 AM UTC+12, Michael Selik wrote:
>
> On Fri, Aug 19, 2016 at 5:01 AM Lawrence D’Oliveiro wrote:
> 
>> It is handy to be able to keep complex expressions together sometimes,
>> when breaking them up would simply obscure their structure.
> 
>     p0 = (0, 0)
>     p1 = (major_dim, 0)
>     colour_stops = (0, rect_1_colour), (1, complement(rect_1_colour))
>     rect_1_pattern = qah.Pattern.create_linear(p0, p1, colour_stops)

That’s an example of what I mean about obscure structure.

>> 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
>>
> 
> No need for the separate calls to isinstance, nor the check for None.
> 
>     if any(not isinstance(obj, Image) for obj in [src, mask, dest]):
>         ...

Spot the bug in your version...