functions vs methods
ben+python at benfinney.id.au
Sun Jul 22 04:01:40 EDT 2018
Sharan Basappa <sharan.basappa at gmail.com> writes:
> Is there a difference between functions and methods in Python.
Python's documentation includes a useful Glossary. See the terms
Every method is a function; but there are functions that are not
What distinguishes a method is that it is associated with a specific
class. A method is always a method *of* some class or object.
> For example, this is the text from tutorialpoint on Python:
> Python includes the following list functions - cmp, len etc.
The functions ‘cmp’, ‘len’, are not associated with any particular
class. They can be called without being bound to any object.
> Python includes following list methods - append, count
That means the functions it is referring to are each methods of ‘list’.
Any instance of ‘list’ has methods ‘append’ and ‘count’, bound to that
> In the first case, len is a function that python provides to which
> list can be passed and in the second case, append is a method within
> list class?
Yes, that's correct.
> If my interpretation is correct, why not make len also as a part of
> list class itself?
Because ‘len’ works with *any* sequence, not only lists. To implement it
as a method of each sequence type, it would have to be implemented on
each type separately, which is a design that is needlessly more complex.
This is common in Python: it uses so-called “duck typing”, where the way
an object behaves is more important than its type. Because “what is the
length of this object” is a question valid for a broad variety of types,
the design decision was made to allow it to accept any type for which
that query makes sense.
Your particular question is itself a FAQ
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`\ positions.” —Adlai Stevenson |
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