On 11/23/20 11:06 AM, Larry Hastings wrote:
> On 11/23/20 8:15 AM, Brian Coleman wrote:
>> def process(root_node: Node):
>> def process_node(node: Node):
>> if isinstance(node, StringNode):
>> return node.value
>> elif isinstance(node, NumberNode):
>> return float(node.value)
>> elif isinstance(node, ListNode):
>> return [process_node(child_node) for child_node in
node.children]
>> elif isinstance(node, DictNode):
>> return {key: process_node(child_node) for key, child_node in
node.children}
>> else:
>> raise Exception('Unexpected node')
>
> You don't need the "else".
Without the "else" errors will pass silently.
> And you can change all your "elif"s into "if"s too.
On average, doubling your comparisons and therefore becoming slower.
> Now your "isinstance" version is 35 lines. Shorter than the pattern matching
version
But without error checking.
> roughly the same speed,
See above comment about becoming slower.
> works in current Python, eminently readable to anybody conversant in current Python. A very reasonable solution to
the problem.
Agreed. But (subjectively, of course) not as elegant as the match version, and deteriorates rapidly as complexity
increases.
> There should be one--and preferably only one--obvious way to do it,
But that is not a hard and fast rule or we wouldn't have decorators (zero lines saved), the "with" statement (two lines
saved), and four different ways spanning three different protocols to write an iterator [1].
--
~Ethan~
[1]
https://stackoverflow.com/questions/19151/build-a-basic-python-iterator/7542261#7542261
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