擅长:python、mysql、java
<p>只需添加一个计数器,就可以限制要在代码中创建的实例数:</p>
<pre><code>class A(object):
ins = 0 # This is a static counter
def __init__(self):
if A.ins >= 1: # Check if the number of instances present are more than one.
del self
print "Failed to create another instance" #if > 1, del self and return.
return
A.ins += 1
print "Success",str(self)
</code></pre>
<p>尝试通过以下方式运行:</p>
^{pr2}$