7. Glossary
- base case
- A branch of the conditional statement in a recursive function that does
not give rise to further recursive calls.
- data structure
- An organization of data for the purpose of making it easier to use.
- exception
- An error that occurs at runtime.
- handle an exception
- To prevent an exception from terminating a program by wrapping
the block of code in a
try / except construct.
- immutable data type
- A data type which cannot be modified. Assignments to elements or
slices of immutable types cause a runtime error.
- infinite recursion
- A function that calls itself recursively without ever reaching the base
case. Eventually, an infinite recursion causes a runtime error.
- mutable data type
- A data type which can be modified. All mutable types are compound
types. Lists and dictionaries (see next chapter) are mutable data
types; strings and tuples are not.
- raise
- To cause an exception by using the
raise statement.
- recursion
- The process of calling the function that is already executing.
- recursive call
- The statement that calls an already executing function. Recursion can
even be indirect — function f can call g which calls h,
and h could make a call back to f.
- recursive definition
- A definition which defines something in terms of itself. To be useful
it must include base cases which are not recursive. In this way it
differs from a circular definition. Recursive definitions often
provide an elegant way to express complex data structures.
- tuple
- A data type that contains a sequence of elements of any type, like a
list, but is immutable. Tuples can be used wherever an immutable type
is required, such as a key in a dictionary (see next chapter).
- tuple assignment
- An assignment to all of the elements in a tuple using a single
assignment statement. Tuple assignment occurs in parallel rather than
in sequence, making it useful for swapping values.