CFSS Week 2 Terminology Recap
function
def my_function(a, b):!
! print “hello world”!
! return a+b
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Coined by Leibniz (C17)
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Euler (C18): “f(x)=x2"
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functions in programming languages: black boxes
that:
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take input
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perform some action
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return some output
“synonyms”: procedure, method, subroutine
call
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To call a function is to invoke it
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When you call a function, the sequence of
operations stored in its black box take place
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“synonyms”: invoke
In[1]: ! my_function(3, 4)!
!
Out[1]: ! “Hello World”!
! ! ! 7
argument / parameter
def my_function(a, b):!
! print “hello world”!
! return a+b
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In the function f(y) = x2:
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The function is named “y”
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The argument (Frege late C19) is named
“x” (also called an input parameter)
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The result is to take a number and return
that number times itself
return value
def my_function(a, b):!
! print “hello world”!
! return a + b
variable / value
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x = 3!
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x = foo()!
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“The variable named x takes on the
value 3”
“The variable x takes on the return
value of the function named foo()!
x == 3!
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“Is the variable x equal to 3?”
operator
def my_function(a, b):!
! print “hello world”!
! return a + b
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a.k.a. an infix function
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as opposed to prefix:
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+34
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plus(3,4)
or postfix (sometimes “Reverse Polish
Notation” or RPN):
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34+
type
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In Python, a variable has one and only one type:
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int: integer
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float: digital approximation of a real number
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str: a “string” or sequence of characters
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list: an ordered sequence of things
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tuple: an unmodifiable ordered sequence of things
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dict: a mapping of things to other things
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…and more
object
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In Python, you can define your own types
using the keyword class
class MyClass:!
"""A simple example class"""!
i = 12345!
def f(self):!
return 'hello world'
keyword
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A keyword is a special word that should
only be used in certain situations in Python,
and not used as the name of a variable.
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Examples:
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def
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and
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if
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while
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int
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break
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elif
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print
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str
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in
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else
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return
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float
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for
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not
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continue
module / import
In [1]: import math!
!
In [2]: math.sin(math.pi/2)!
Out[2]: 1.0
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A bunch of code somewhere else
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Specifically:
In [3]: math!
Out[3]: <module 'math' from '/usr/local/Cellar/python/
2.7.9/Frameworks/Python.framework/Versions/2.7/lib/
python2.7/lib-dynload/math.so'>
method (vs. function)
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A method is a function which is
“owned and operated by” an object
In[1]: !my_string = “hello world”!
! ! ! print my_string.split()!
Out[1]:!['Hello', 'World']
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As opposed to “global” functions:
In[1]: !my_string = “hello world”!
! ! ! print len(my_string)!
Out[1]:!11
expression
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An expression is basically any minimally
syntactically valid chunk of code
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x == 3!
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x = 3!
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x and y
… and more
!
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algorithm
element
index
reference
key-value pair
implementation
hash
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lookup
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scope
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exception
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parse
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syntax
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condition
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sequence
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slice