CODEWITHSUNDEEP
python
Zeynel
Zeynel

Reputation: 13515

How to initialize empty list?

Every time the input s comes from the form; the list is initialized again. How do I change the code to append each new s to the list?

Thank you.

class Test(webapp.RequestHandler):
    def get(self):

        s = self.request.get('sentence')
        list = []                                   
        list.append(s)                      
        htmlcode1 = HTML.table(list)

Upvotes: 12

Views: 54271

Answers (2)

dln385
dln385

Reputation: 12090

I'm not sure what the context of your code is, but this should work:

class Test(webapp.RequestHandler):
    def get(self):
        s = self.request.get('sentence')
        try:
            self.myList.append(s)
        except NameError:
            self.myList= [s]
        htmlcode1 = HTML.table(self.myList)

This makes list an instance variable so it'll stick around. The problem is that list might not exist the first time we try to use it, so in this case we need to initialize it.

Actually, looking at this post, this might be cleaner code:

class Test(webapp.RequestHandler):
    def get(self):
        s = self.request.get('sentence')
        if not hasattr(self, 'myList'):
            self.myList = []
        self.myList.append(s)
        htmlcode1 = HTML.table(self.myList)

[Edit:] The above isn't working for some reason, so try this:

class Test(webapp.RequestHandler):
    myList = []
    def get(self):
        s = self.request.get('sentence')
        self.myList.append(s)
        htmlcode1 = HTML.table(self.myList)

Upvotes: 6

sth
sth

Reputation: 229593

You could make the list a member variable of the object and then only update it when get() is called:

class Test(webapp.RequestHandler):
    def __init__(self, *p, **kw): # or whatever parameters this takes
        webapp.RequestHandler.__init__(self, *p, **kw)
        self.list = []

    def get(self):
        s = self.request.get('sentence')
        self.list.append(s)                      
        htmlcode1 = HTML.table(self.list)

Upvotes: 5

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