If I am using the python module queue.Queue, I want to be able to print out the contents using a method that does not pop the original queue or create a new queue object.
I have tried looking into doing a get and then putting the contents back but this is too high cost.
# Ideally it would look like the following
from queue import Queue
q = Queue()
q.print()
q.put(1)
q.print()
>> [] # Or something like this
>> [1] # Or something like this
>>> print(list(q.queue))
Does this work for you?
Assuming you are using python 2. You can use something like this:
from queue import Queue
q = Queue.Queue()
q.put(1)
q.put(2)
q.put(3)
print q.queue
You can also loop on it :
for q_item in q.queue:
print q_item
But unless you are dealing with threads, I would use a normal list as a Queue implementation.
Sorry, I am a bit late to answer this question, but going by this comment, I extended the Queue in the multiprocessing package as per your requirements. Hopefully it will help someone in the future.
import multiprocessing as mp
from multiprocessing import queues
class IterQueue(queues.Queue):
def __init__(self, *args, **kwargs):
ctx = mp.get_context()
kwargs['ctx'] = ctx
super().__init__(*args, **kwargs)
# <---- Iter Protocol ------>
def __iter__(self):
return self
def __next__(self):
try:
if not self.empty():
return self.get() # block=True | default
else:
raise StopIteration
except ValueError: # the Queue is closed
raise StopIteration
Given below is a sample usage of this IterQueue I wrote:
def sample_func(queue_ref):
for i in range(10):
queue_ref.put(i)
IQ = IterQueue()
p = mp.Process(target=sample_func, args=(IQ,))
p.start()
p.join()
print(list(IQ)) # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
I have tested this IterQueue for even a few more complex scenarios, and it seems to be working fine. Let me know if you think this works, or it could fail in some situation.
not sure if this is still a question, but using the name.queue (i.e. q.queue here) works for me. This works also for the other types of queues in the module.
import queue
q = queue.Queue()
print(list(q.queue))
q.put(1)
print(list(q.queue))
The most common way to print the content of the queue if you are not using the queue then use this code snippet:
class Queue:
def __init__(self):
self.items = []
def push(self, e):
self.items.append(e)
def pop(self):
head = self.items[0]
self.items = self.item[1:]
return head
def print(self):
for e in self.items:
print(e)
q = Queue()
q.push(1)
q.push(23)
q.print()
OUTPUT
1
23
