Multiton: Difference between revisions
Added Python
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=={{header|Python}}==
{{works with|Python|3.x}}
<syntaxhighlight lang="python">#!/usr/bin/python
import threading
class Multiton:
def __init__(self, registry, refnum, data=None):
with registry.lock:
if 0 < refnum <= registry.max_instances and registry.instances[refnum] is None:
self.data = data
registry.instances[refnum] = self
elif data is None and 0 < refnum <= registry.max_instances and isinstance(registry.instances[refnum], Multiton):
self.data = registry.instances[refnum].data
else:
raise Exception("Cannot create or find instance with instance reference number {}".format(refnum))
class Registry:
def __init__(self, maxnum):
self.lock = threading.Lock()
self.max_instances = maxnum
self.instances = [None] * maxnum
reg = Registry(3)
m0 = Multiton(reg, 1, "zero")
m1 = Multiton(reg, 2, 1.0)
m2 = Multiton(reg, 1)
m3 = Multiton(reg, 2)
for m in [m0, m1, m2, m3]:
print("Multiton is {}".format(m.data))
# produce error
#m2 = Multiton(reg, 3, [2])
# produce error
# m3 = Multiton(reg, 4, "three")
# produce error
# m5 = Multiton(reg, 5)</syntaxhighlight>
=={{header|Raku}}==
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