How Does Python's `repr()` Function Work, and Why Are Strings Double-Quoted in Its Output?

Understanding the repr( ) Function in Python

Python's repr( ) function returns an evaluatable string representation of an object. This means that the string can be used to recreate the same object using eval( ).

Why double quotes when using repr( ) on strings?

When repr( ) is applied to a string, it surrounds the string with double quotes. This helps distinguish the string from other types of objects, such as integers or lists.

Why eval("'foo'") returns 'foo' instead of x?

When eval( ) is called with a string, it interprets the string as a Python expression. If the string contains a valid expression, it evaluates it and returns the result. In the case of eval("'foo'"), the expression is a string literal, so it evaluates to the same string. On the other hand, x is a variable that refers to the string 'foo'. When eval( ) is called with x, it attempts to evaluate x as a Python expression, which fails because x is not a valid expression.

The __repr__() method

repr( ) actually calls the __repr__() method of the object. This method returns the evaluatable string representation of the object.

str( ) vs. repr( )

In contrast to repr( ), str( ) returns a string representation of the object suitable for display. It does not surround strings with double quotes and does not contain any special characters to indicate that the string is meant to be evaluated.

Summary:

• repr( ) returns an evaluatable string representation of an object.
• repr( ) surrounds strings with double quotes to distinguish them from other types of objects.
• eval( ) interprets a string as a Python expression and executes it.
• Objects that extend the built-in types can provide custom implementations of __repr__() and __str__().
• repr( ) is useful for debugging and introspection, while str( ) is suitable for user-facing output.

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