问环境变量中的Python环境变量

EN

>>> import os
>>> print os.path.expandvars("My home directory is $HOME")
My home director is /home/Majaha
>>> 

os.environ["myRoot"] = "/home/myName"
os.environ["subDir"] = os.path.expandvars("$myRoot/subDir")

os.environ["myRoot"]="/home/myName" 
os.environ["subDir"] = os.path.join(os.environ['myRoot'], "subDir")

def fix_text(txt,data):
    '''txt is the string to fix, data is the dictionary with the variable names/values'''
    def fixer(m): #takes a regex match 
         match = m.groups()[0] #since theres only one thats all we worry about
         #return a replacement or the variable name if its not in the dictionary
         return data.get(match,"$%s"%match) 
    return re.sub("$([a-zA-Z]+)",fixer,txt) #regular expression to match a "$" followed by 1 or more letters

with open("some.json") as f: #open the json file to read
    file_text= f.read()
data = json.loads(file_text) #load it into a json object
#try to ensure you evaluate them in the order you found them
keys = sorted(data.keys() ,key=file_text.index) 
#create a new dictionary by mapping our ordered keys above to "fixed" strings that support simple variables
data2= dict(map(lambda k:(k,fixer(data[k],data)),keys)
#sanity check
print data2