Returning from a multiple stacked call at once

[ast]

Le 12/12/2020 à 09:18, Cameron Simpson a écrit :
> On 12Dec2020 07:39, ast <ast at invalid> wrote:
>> In case a function recursively calls itself many times,
>> is there a way to return a data immediately without
>> unstacking all functions ?
> 
> Not really. Do you have an example where this is inconvenient?
> 
> There are alternatives, for example passing in a Queue and put()ing the
> data onto the queue. It's quite dependent on what you're trying to do
> though.
> 
> Cheers,
> Cameron Simpson <cs at cskk.id.au>
> 

I don't really need it. I was just wondering and guessed it was
not feasible.

Here is a code where it would be useful. This code looks for a
path in a graph.
If the found path is long, say 100 nodes, then path_finder calls
itself recursively 100 times, and has to unstack 100 times to
provide the found path. It could be returned immediately.


def path_finder(graph, start, end, path=[]):	

	if start in path:
		return None
	if start == end:
		return path + [start]   # Found !
	if start not in graph:
		return None
	
	path = path + [start]

	for node in graph[start]:
		found_path = path_finder(graph, node, end, path)
		if found_path:
			return found_path
	return None

graph = {'A': ['B', 'C'],
              'B': ['C', 'D'],
              'C': ['D'],
              'D': ['C'],
              'E': ['F'],
              'F': ['C']}

path_finder(graph, 'A', 'D')