"Python" an Introduction to Interactive programming in Python (week)

This was a note for https://class.coursera.org/interactivepython-005

In Week II, I have learned:

1.event-drvien Programing

4 Event Types:

Input: Button, textbox

Keyborad: Key up, key down

Mouse: Click, drag

Timer

Example

# Example of a simple event-driven program# codeskulptor GUI moduleimport simplegui# event Handlerdef tick ():    print "t ick! " # Register Handlertimer = Simplegui.create_timer (+, tick) # Start Timertimer.start ()

2. Global variables

When you want-to-change the global variables, use global, ifelse-t need global. (No global variables need to be changed, only when you want to use the values of global variables, you don't have to declare global)

3. Simplegui

Program structure with 7 steps:

①globals (state)

②helper functions

③classes

④define Event handlers

⑤create A Frame

⑥register Event handlers

⑦start Frame & Timers

#Simplegui Program Template#Import the moduleImportSimplegui#Define Global Variables ( program state)Counter =0#Define "helper" functionsdefincrement ():GlobalCounter Counter= counter + 1#Define event handler functionsdeftick (): Increment ()PrintcounterdefButtonPress ():GlobalCounter Counter=0#Create A Frameframe = Simplegui.create_frame ("Simplegui Test", 100, 100) Frame.add_button ("Click me!", ButtonPress)#Register Event HandlersTimer = Simplegui.create_timer (1000, tick)#Start frame and timersFrame.start () Timer.start ( )

Simple Calculator

Data

Store

Operand

Operations

Print

Swap

Add

Subtract

Multiple

Divide

Computation

store = store operation operand

#Calculator with all buttonsImportSimplegui#intialize Globalsstore =0operand=0#event handlers for calculator with a store and operanddefoutput ():"""prints contents of store and operand"""    Print "Store =", StorePrint "Operand =", operandPrint ""    defswap ():"""swap contents of store and operand"""    Globalstore, operand store, operand=operand, store output ()defAdd ():"""add operand to store"""    GlobalStore Store= store +operand output ()defSub ():"""subtract operand from store"""    GlobalStore Store= Store-operand output ()defmult ():"""multiply store by operand"""    GlobalStore Store= Store *operand output ()defDiv ():"""divide store by operand"""    GlobalStore Store= store/operand output ()defEnter (t):"""Enter a new operand"""    Globaloperand operand=int (t) output ()#Create framef = simplegui.create_frame ("Calculator", 300,300)#register event handlers and create control elementsF.add_button ("Print", Output, 100) F.add_button ("Swap", swap, 100) F.add_button ("ADD", add, 100) F.add_button ("Sub", Sub, 100) F.add_button ("Mult", Mult, 100) F.add_button ("Div", Div, 100) F.add_input ("Enter", enter, 100)#Get frame rollingF.start ()

"Python" an Introduction to Interactive programming in Python (week)