Question

In the below code, the compiler is giving me the error “Local variable shouldStoreData” referenced before assignment. But I am assigning it first.

class MyHTMLParser(HTMLParser):
    shouldStoreData = False
    textPartDoc = ""
    def handle_starttag(self, tag, attrs):
        print "Encountered a start tag:", tag
        if(tag == "title" or tag == "body"):
            shouldStoreData = True
    def handle_endtag(self, tag):
        print "Encountered an end tag :", tag        
    def handle_data(self, data):
        #print "Data is",data
        #print "valus of storeData is:",shouldStoreData
        if(shouldStoreData == True):
            textPartDoc  = textPartDoc + " " + data
            shouldStoreData = False

What I am trying to do here is that I want to store the data only when the tag is title or any tag within body.

Answer 1

The first shouldStoreData is a class attribute. The ones inside handle_starttag and handle_data are local variables. In handle_data, you test the variable before you assign it. Code inside the method doesn’t know that the class attribute exists unless you explictly access it as a class/instance attribute (e.g., self.shouldStoreData or MyHTMLParser.shouldStoreData).

If you want shouldStoreData to be an instance attribute, then you need to write an __init__ method and create it as an instance attribute:

def __init__(self):
    self.shouldStoreData = False

and then later refer to it as self.shouldStoreData in your other methods.

You should read the Python tutorial to get a grasp of the basics of classes, attributes, and methods in Python.