Python repr()

The Python repr() built-in function returns a string containing a printable, unambiguous representation of an object. It accepts a single parameter, the object whose representation you want to obtain, and returns a string that ideally could be used to recreate the object using eval(). The key distinction between repr() and str() is that repr() is designed for developers and debugging, producing output that clearly shows the type and value of the object, including quotes around strings and escape characters for special characters. For custom classes, repr() calls the object’s __repr__() method, which you can override to provide meaningful debug output. Real-world use cases include logging object states during debugging, generating diagnostic output in error messages, serializing objects to a human-readable format for inspection, and implementing the __repr__() method in custom classes to make them easier to debug in interactive Python sessions and log files.

What does repr() return?

The repr() function returns a string that is an unambiguous, developer-oriented representation of the given object, typically including type information and quotes around string values.

When should you use repr()?

Use repr() when you need an unambiguous string representation of an object for debugging, logging, or diagnostic purposes, especially when str() output would be ambiguous or lose important type information like quotes around strings.

The syntax of repr() is:

repr(object_name)

repr() Parameters

The repr() function only take one parameter as an argument:

• object_name - the name of the object whose information has to be returned.

Let’s check some examples of the python repr() function.

Example 1: How to use the repr() function in python?

object_name = "Python"

print(repr(object_name))

Output:

'Python'

In the above program, we assign a value “Python” to the object_name variable. Then the repr() function returns “Python” or ‘Python’ inside double-quotes.

Common Use Cases

Debugging and logging are the primary applications of repr(). When writing log messages that include variable values, using repr() ensures that strings are shown with quotes, special characters are escaped, and the exact type and content of the object are clear. This is far more informative than str() when diagnosing issues in production logs.

Implementing __repr__() in custom classes is a best practice that repr() supports. By defining a __repr__() method that returns a string like ClassName(arg1, arg2), you make your objects self-documenting in interactive sessions, debuggers, and error tracebacks, which significantly improves development productivity.

Generating test assertions and data snapshots is another practical use. When writing tests, you can use repr() to capture the exact state of an object and compare it against expected values, ensuring that subtle differences in type or formatting are caught.

For user-facing string output, see the Python str() function, which produces a more readable representation. To format strings with more control over layout and precision, the Python format() function is a useful complement.

Rules of repr()

• repr() will return a string representing a given object; if the integer is given, it will return it as a string.