getattr的使用. 一个hackerrank的列表题

https://www.hackerrank.com/challenges/python-lists

主要是涉及到 getattr和eval, exec的应用

Task 
You have to initialize your list L = [] and follow the NN commands given in NN lines.

Each command will be 11 of the 88 commands given above. The method extend(L) will not be used. Each command will have its own value(s) separated by a space.

For example:

Sample Input

12
insert 0 5
insert 1 10
insert 0 6
print 
remove 6
append 9
append 1
sort 
print
pop
reverse
print

Sample Output

[6, 5, 10]
[1, 5, 9, 10]
[9, 5, 1]

几种解法:

T = int(input().strip())
L = []
for t in range(T):
    args = raw_input().strip().split(" ")
    if args[0] == "print":
        print L
    elif len(args) == 3:
        getattr(L, args[0])(int(args[1]), int(args[2]))
    elif len(args) == 2:
        getattr(L, args[0])(int(args[1]))
    else:
        getattr(L, args[0])()

L = []
for _ in range(int(input())):
    command, *args = input().split()
    try:
        getattr(L, command)(*(int(x) for x in args))
    except AttributeError:
        print(L)

n = input()
L = []
for _ in range(n):
    s = input().split()
    cmd = s[0]
    args = s[1:]
    if cmd !="print":
        cmd += "("+ ",".join(args) +")"
        eval("L."+cmd)
    else:
        print (L)

或:

T = int(input())
L = []
for i in range(T):
    commands = input().strip().split()
    if commands[0] == 'print':
        print(L)
    else:
        fullcommand = 'L.' + commands[0] + '(' + ','.join(commands[1:]) + ')'
        exec (fullcommand)