Python實現簡單的緩存和緩存decorator

一個簡單的緩存實現，將緩存數據保存在單例的對象中。

使用方法：

 # Initialize
    SimpleCache({'data':{'example':'example data'}})


# Getting instance
c = SimpleCache.getInstance()

c.set('re.reg_exp_compiled',re.compile(r'\W*'))
reg_exp = c.get('re.reg_exp_compiled',default=re.compile(r'\W*'))

# --------------------------------------------------------------

c = SimpleCache.getInstance()
reg_exp = c.getset('re.reg_exp_compiled',re.compile(r'\W*'))

# --------------------------------------------------------------    

@scache
def func1():
    return 'OK'</pre> 


 實現
author = "Andrey Nikishaev"
copyright = "Copyright 2010, http://creotiv.in.ua&quot;
license = "GPL"
version = "0.3"
maintainer = "Andrey Nikishaev"
email = "creotiv@gmail.com"
status = "Production"

"""
Simple local cache.
It saves local data in singleton dictionary with convenient interface
Examples of use:

# Initialize
SimpleCache({'data':{'example':'example data'}})
# Getting instance
c = SimpleCache.getInstance()

c.set('re.reg_exp_compiled',re.compile(r'\W*'))
reg_exp = c.get('re.reg_exp_compiled',default=re.compile(r'\W*'))


or

c = SimpleCache.getInstance()
reg_exp = c.getset('re.reg_exp_compiled',re.compile(r'\W*'))


or
    @scache
    def func1():
        return 'OK'
"""
class SimpleCache(dict):

def __new__(cls,*args):
    if not hasattr(cls,'_instance'):
        cls._instance = dict.__new__(cls)
    else:
        raise Exception('SimpleCache already initialized')
    return cls._instance

@classmethod
def getInstance(cls):
    if not hasattr(cls,'_instance'):
        cls._instance = dict.__new__(cls)
    return cls._instance

def get(self,name,default=None):
    """Multilevel get function.
    Code:        
    Config().get('opt.opt_level2.key','default_value')
    """
    if not name: 
        return default
    levels = name.split('.')
    data = self            
    for level in levels:
        try:            
            data = data[level]
        except:
            return default

    return data

def set(self,name,value):
    """Multilevel set function
    Code:        
    Config().set('opt.opt_level2.key','default_value')
    """
    levels = name.split('.')
    arr = self        
    for name in levels[:-1]:
        if not arr.has_key(name):         
            arr[name] = {}   
        arr = arr[name]
    arr[levels[-1]] = value

def getset(self,name,value):
    """Get cache, if not exists set it and return set value
    Code:        
    Config().getset('opt.opt_level2.key','default_value')
    """
    g = self.get(name)
    if not g:
        g = value
        self.set(name,g)
    return g


def scache(func):
    def wrapper(args, **kwargs):
        cache = SimpleCache.getInstance()
        fn = "scache." + func.module + func.class.name + \
             func.name + str(args) + str(kwargs)

        val = cache.get(fn)
        if not val:
            res = func(args, **kwargs)
            cache.set(fn,res)
            return res
        return val
    return wrapper
</pre>