copy.py 文件源码

def _deepcopy_tuple(x, memo):
    y = []
    for a in x:
        y.append(deepcopy(a, memo))
    d = id(x)
    try:
        return memo[d]
    except KeyError:
        pass
    for i in range(len(x)):
        if x[i] is not y[i]:
            y = tuple(y)
            break
    else:
        y = x
    memo[d] = y
    return y