fmt.Printf("%q\n", strings.Split("a,b,c", ","))
fmt.Printf("%q\n", strings.Split("a man a plan a canal panama", "a "))
fmt.Printf("%q\n", strings.Split(" xyz ", ""))
fmt.Printf("%q\n", strings.Split("", "Bernardo O'Higgins"))
在看《build web application with golang》地址：https://github.com/astaxie/build-web-application-with-golang
看到Panic和Recover这一节，对Panic和Recover有了了解。
Go没有例如像Java那样的异常机制：不能抛出一个异常。作为代替，它使用了panic和recover机制。一定要记得，这应当作为最后的手段被使用，你的代码中应当没有，或者很少的令人恐慌的东西。这是个强大的工具，明智的使用它。那么，应该如何使用它。
Panic
package main
import(
"fmt"
//"os"
)
var user = ""
func inita() {
defer func(){
fmt.Print("defer##\n")
}()
if user == "" {
fmt.Print("@@@before panic\n")
panic("no value for user\n")
fmt.Print("!!after panic\n")
}
}
func throwsPanic (f func()) (b bool){
defer func(){
if x:= recover(); x != nil{
fmt.Print(x)
b = true
}
}()
f()
fmt.Print("after the func run")
return
}
func main(){
throwsPanic(inita)
}
执行结果：
D:\go>go run b.go
@@@before panic
defer##
no value for user
如上面所说的：
panic在user=""时，打断了函数的执行，fmt.Print("!!after panic\n")没有执行。
但函数中的延迟函数会正常执行，打印了 ”defer##“。然后返回到调用该函数的地方，继续上面的过程。
直到执行完所有函数的defer，退出程序。
Recover可以捕获到panic的值，上面的打印“no value for user”。并且恢复正常的执行。
Welcome To PyCrust 0.7.2 - The Flakiest Python Shell
Sponsored by Orbtech - Your source for Python programming expertise.
Python 2.2.1 (#1, Aug 27 2002, 10:22:32)
[GCC 3.2 (Mandrake Linux 9.0 3.2-1mdk)] on linux-i386
Type "copyright", "credits" or "license" for more information.
>>> import cPickle as pickle
>>> t1 = ('this is a string', 42, [1, 2, 3], None)
>>> t1
('this is a string', 42, [1, 2, 3], None)
>>> p1 = pickle.dumps(t1)
>>> p1
"(S'this is a string'\nI42\n(lp1\nI1\naI2\naI3\naNtp2\n."
>>> print p1
(S'this is a string'
I42
(lp1
I1
aI2
aI3
aNtp2
.
>>> t2 = pickle.loads(p1)
>>> t2
('this is a string', 42, [1, 2, 3], None)
>>> p2 = pickle.dumps(t1, True)
>>> p2
'(U\x10this is a stringK*]q\x01(K\x01K\x02K\x03eNtq\x02.'
>>> t3 = pickle.loads(p2)
>>> t3
('this is a string', 42, [1, 2, 3], None)
>>> j = [1, 2, 3]
>>> k = j
>>> k is j
1
>>> x = pickle.dumps(k)
>>> y = pickle.loads(x)
>>> y
[1, 2, 3]
>>> y == k
1
>>> y is k
0
>>> y is j
0
>>> k is j
1
class Foo(object):
def __init__(self, value):
self.value = value
现在可以 pickle Foo 实例，并看一下它的表示：
清单 12. pickle Foo 实例
>>> import cPickle as pickle
>>> from Orbtech.examples.persist import Foo
>>> foo = Foo('What is a Foo?')
>>> p = pickle.dumps(foo)
>>> print p
ccopy_reg
_reconstructor
p1
(cOrbtech.examples.persist
Foo
p2
c__builtin__
object
p3
NtRp4
(dp5
S'value'
p6
S'What is a Foo?'
sb.
>>>
>>> import cPickle as pickle
>>> f = file('temp.pkl', 'r')
>>> foo = pickle.load(f)
Traceback (most recent call last):
File "", line 1, in ?
ImportError: No module named persist
class Foo(object):
def __init__(self, value, filename):
self.value = value
self.logfile = file(filename, 'w')
def __getstate__(self):
"""Return state values to be pickled."""
f = self.logfile
return (self.value, f.name, f.tell())
def __setstate__(self, state):
"""Restore state from the unpickled state values."""
self.value, name, position = state
f = file(name, 'w')
f.seek(position)
self.logfile = f
假定已经创建并 pickle 了 Person 的实例，现在我们决定真的只想存储一个名称属性，而不是分别存储姓和名。这里有一种方式可以更改类的定义，它将先前经过 pickle 的实例迁移到新的定义：
清单 18. 新的类定义
class Person(object):
def __init__(self, fullname):
self.fullname = fullname
def __setstate__(self, state):
if 'fullname' not in state:
first = ''
last = ''
if 'firstname' in state:
first = state['firstname']
del state['firstname']
if 'lastname' in state:
last = state['lastname']
del state['lastname']
self.fullname = " ".join([first, last]).strip()
self.__dict__.update(state)