CODEWITHSUNDEEP
pythonstringclass
kroneckersdelta
kroneckersdelta

Reputation: 55

returning a string from a class object with __str__

Im having trouble with this fifo-queue program, i've worked out most of the code, which looks like this:

class fifoQueue:

    __L = []
        def __init__(self):
        self.__L = []


    def __len__(self):
        return len(self.__L)


    def empty(self):
        if len(q) == 0:
            return True
        else:
            return False


    def enqueue(self, e):
        self.__L.insert(0, e)
            return self.__L


    def dequeue(self):
        if self.empty():
            self.__L = [e]
        else:
            return self.__L.pop()

    def __str__(self):
        return "'" + str(self.__L) + "'"

the problem I have is with the __ str __(self) function, what I want it to do is to return my list self.__L with "'" if I call print(str(q)), but if I only call print(q) I want it to return the list. Right now I get the same output for both print(q) and print(str(q)).

(print(str(q)) returns '[31.0]'
print(q) returns '[31.0]'

whereas I would like it to return

str(q) returns '[31.0]' or print(str(q)) returns '[31.0]'
print(q) returns [31.0]

I come from a background in mathematics and this is one of the first languages im learning so I apologize if this is very basic. This is an assignment where I have to only use __ str __ to accomplish this, no additional functions can be created. Any directions are greatly appreciated.

Upvotes: 1

Views: 3882

Answers (1)

Matt Eding
Matt Eding

Reputation: 1002

The __str__ method should be as follows:

 def __str__(self):
      return str(self.__L)    # delegate to built-in function (no concatenation with quote)

Or:

def __str__(self):
    return '{self.__L !s}'.format(self.__L)    # string formatting

Upvotes: 1

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