Python Language Reference Manual by Guido van Rossum and Fred L. Drake, Jr. Paperback (6"x9"), 120 pages ISBN 0954161785 RRP £12.95 ($19.95) Sales of this book support the Python Software Foundation! Get a printed copy>>>

Python Language Reference Manual Buy the book here! >>> only $19.95

5.2.7 String conversions

A string conversion is an expression list enclosed in reverse (a.k.a. backward) quotes:

string_conversion "`" expression_list "`"

A string conversion evaluates the contained expression list and converts the resulting object into a string according to rules specific to its type.

If the object is a string, a number, None, or a tuple, list or dictionary containing only objects whose type is one of these, the resulting string is a valid Python expression which can be passed to the built-in function eval() to yield an expression with the same value (or an approximation, if floating point numbers are involved).

(In particular, converting a string adds quotes around it and converts "funny" characters to escape sequences that are safe to print.)

Recursive objects (for example, lists or dictionaries that contain a reference to themselves, directly or indirectly) use ‘...’ to indicate a recursive reference, and the result cannot be passed to eval() to get an equal value (SyntaxError will be raised instead).

The built-in function repr() performs exactly the same conversion in its argument as enclosing it in parentheses and reverse quotes does. The built-in function str() performs a similar but more user-friendly conversion.