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28.8.4: Objects and Values

  • Page ID
    103199
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    If we execute these assignment statements:

    a = 'banana'
    b = 'banana'

    we know that a and b both refer to a string, but we don't know whether they refer to the same string. There are two possible states:

    Variables and Objects

    Variables and Objects

    In one case, a and b refer to two different objects that have the same value. In the second case, they refer to the same object.

    To check whether two variables refer to the same object, you can use the is operator.

    >>> a = 'banana'
    >>> b = 'banana'
    >>> a is b
    True

    In this example, Python only created one string object, and both a and b refer to it.

    But when you create two lists, you get two objects:

    >>> a = [1, 2, 3]
    >>> b = [1, 2, 3]
    >>> a is b
    False

    In this case we would say that the two lists are equivalent, because they have the same elements, but not identical, because they are not the same object. If two objects are identical, they are also equivalent, but if they are equivalent, they are not necessarily identical.

    Until now, we have been using "object" and "value" interchangeably, but it is more precise to say that an object has a value. If you execute a = [1,2,3], a refers to a list object whose value is a particular sequence of elements. If another list has the same elements, we would say it has the same value.


    This page titled 28.8.4: Objects and Values is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Chuck Severance via source content that was edited to the style and standards of the LibreTexts platform.

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