[Tutor] Can anyone help answer this?

[Peter Otten]

Alan Gauld via Tutor wrote:

> On 10/06/2020 03:29, Christine Mason wrote:
>> Given the following class definition:
>> 
>>  class Food:
>> 
>>      def __init__(self, name, taste):
>>         self.name = name
>>         self.taste = taste
>> 
>>  Write a function *createFood()* that takes a list of food items as
>> argument and creates an instance of class Food for each of them.  It then
>> returns the list of instances that it has created.
>> 
>>  Each food item in the list that is passed as argument to *createFood()
>>  *is
>> a tuple of the form ('name', 'taste'), so the list of food items might
>> look like this:
>> 
>>  [('curry', 'spicy'), ('pavlova', 'sweet'), ('chips', 'salty')]
>> 
>>  The function *createFood() *takes the two elements of each tuple and
>> passes them to the initialiser of Food.  It then collects the objects
>> returned by the initialiser and adds them to the list that is returned by
>> createFood().
> 
> I really hate when students (and I assume is is a homework/tutorial
> exercise) get asked to write bad code. This function should be
> entirely unnecessary. 

It were unnecessary if it should create a single instance. For a whole list 
I think it's fine -- except that the name is misleading.

> The function for creating instances is the
> constructor - it's already written. We don't need another.
> 
> And the Pythonic way of building lists is a list comprehension.
> So this whole exercise should be reduced to:
> 
> food_list = [Food(t) for t in tuple_list]

You forgot the * which I think is an advanced and even somewhat questionable 
feature. 

To go to the other end of the spectrum of possible solutions, the teacher 
may well see attempts like

def create_food_list(pairs):
    for i in range(len(pairs)):
        name = pairs[i][0]
        taste = pairs[i][1]
        food = Food(name, taste)
        pairs[i] = food
    return pairs

which gives opportunities to show

- idiomatic iteration
- tuple unpacking
- good ways for a function to communicate with its caller.

You may argue that this should have been taught before starting with custom 
objects...
 
> If we are going to teach objects lets use the objects!