Programming on the Go Chapters 1and 2

Siddharth Patel1000773753

INSTALLING TOUCHDEVELOP

INSTALLING TOUCHDEVELOP

SCRIPTING LANGUAGESCRIPTING LANGUAGE

IMPORTANT WEBSITESIMPORTANT WEBSITES

Administrator

INTRODUCTIONINTRODUCTION

What Is Touchdevelop-definitionWhat Is Touchdevelop-definitionTouchDevelop is an application development environment which allows users to script and design applications their mobile devices.

• The apps developed using Touchdevelop can use sensors, media, data on mobile, tablets or PC

• The scripts can interacts with cloud services including storage computing and social networks.

What Can Be Done Using Touchdevelop?

Games ,productive apps, personalized phone …

• In future smartphone might me the only computing device.

SMARTPHONE CAPABILITIES

Yes TEXT

Yes TALK

Yes EMAIL

Yes GAMES

Yes NAVIGATION

No PROGRAMMING

Traditional Mobile App Development TechniqueTraditional Mobile App Development Technique

• Use Computer to make mobile App

• Download APIs, SDK or need specific software

• For testing on mobile connect phone to computers

• Share project with teammates using hosting server

Touchdevelop Benefits and ChallengesTouchdevelop Benefits and Challenges

• No specific device need

• No need to install huge SDKs for do specific settings.

• Share project or scripts with teammates on touchdevelop itself

BenefitsBenefits ChallengesChallenges• Mobile Phone

Small Screen

• No Keyboard

• Touch screen interface as input

Installing Touchdevelop on a Windows Phone

1. Tap the Marketplace tile on the Windows phone.2. Press the search icon at the bottom of the screen, and type

the text ‘touchdevelop’ into the Marketplace Search text box. Before you finish typing all the letters, the TouchDevelop app should appear as a choice on the screen.

3. Tap that choice to select it.4. Tap Install.

Installing Touchdevelop on Other Platforms

Touchdevelop runs on web browser on any device

Supported Browsers•IE 10•Chrome(mobile)•Firefox•Safari(mobile)

1. Go to https://www.touchdevelop.com/app/#

2. Log in and that’s it!

The TouchDevelop Ecosystem the script can be shared on cloud

infrastructureA user can share, comment, like

the scriptsUser can find scripts in different

categories like new, top featured, installed.

The Web interface

It’s the same as the phone interface

MouseKeyboardLarger screen

helps to increase productive to user might prefer the web interface but the PC may not have all the sensors like phone (GPS).

Demo

The Scripting Language

• Statement oriented.

• Statements are executed in a sequential manner.

• The language is strongly typed.

• Its not an object oriented language.

Data types

• The Invalid Value: every data type has special value as Invalid value, it is assigned to show that the global variable has not been initialized or the method was unable to return the value. Example

var numUsers := 0…if connection failure detected thennumUsers := invalid → numberelse…if numUsers → is invalid then“Script is terminating” → post to wallelse

The Invalid Type

The Nothing Type

• A method or an operation which does not return a usable result, but which otherwise succeeded, actually returns a value of type Nothing.

• The sole value of type Nothing does not require any storage. Therefore this type is neither a value type nor a reference type. It is a special case.

Data types contd.

Value TypeValue types storages on the stack used for local variables. The storage is automatically deallocated on exit from an action.(Actions is called functions in other langualges ).

Number:• combines the integer and floating-point• IEEE 754 (plus infinity, minus infinity can be computed)

String : • A sequence of zero or more Unicode characters.• Showed as doublequote and backslash are used for special characters.

Boolean:• The type whose constants are true and false.

Data types contd. Value Type

Reference Type

• Global defined variables are stored as Reference Type.• Storage for an instance of a reference type is allocated in a

different place from a variable declared with that type. A local variable with a reference type is implemented as a pointer (a reference) to the actual value which is stored elsewhere.

• If the value represents any entity which exists outside TouchDevelop, then storage is allocated outside the TouchDevelop application.

• Otherwise the storage is allocated within an area of memory controlled by TouchDevelop which is called the heap.

Data types contd.

Reference TypeData types contd.

Reference TypeData types contd.

Reference TypeData types contd.

Collection Types• Touchdevelop provides homogeneous collections.• A collection contains zero or more elements whose type is one of the value

types or one of the reference types• Collections which allow to insert or delete an element is called mutable,

others are immutable .

Data types contd.

Art Items

Some scripts need to display pictures or to produce sounds. These pictures or sounds can be added to the script as global constants and become part of the script. Such items are held in the Art section of the script.

ExpressionsExplicit Constants

Number constants are regular IEEE 754 standard 64 bit floating point numbers.

String constants can be entered using Touchdevelop editor and string is implemented as Sequence of Unicode characters.

Named Constants

Touchdevelop has mechanism to construct constants for color and sounds. Such constants are called name constants.

Demo

VariablesLocal Variables

Local variables follow the usual visibility rules and lifetime rules for block structured languages.

var s1 := “Hello!”

Global Data Variables

The data section of a script contains declarations for variables which are accessible by all actions within the script.If the type is Number, Boolean, String or DateTime, the variable has a neutral initial value. It is 0, false, “” or 1 January 0001 12:00 am respectively. For any other datatype, the initial value is invalid.An access to a global data variable inside a script uses the special symbol ◳ .

◳game := media → create board(480)

Operators

Operators Contd..

StatementsExpression: Any expression may be used as a statement. For example, this is a valid statement.

(“Hello “ || “ there!”) → post to wall

Declaration and Assignment: A declaration of a local variable is combined with an assignment to initialize the variable.

var places := collections → create location collectionIf an action has more than one return parameter.

var street name := “”var street number := 0street name, street number := ▷Get Address Info(“Joanie”)

If Statement: The TouchDevelop editor always generates the if-then-else form for an ifstatement, supplying empty bodies for the then clause and the else clause.

if a < b thenif a < c thenmin := aelse min := celse if b < c thenmin := belsemin := c

Statements Contd..

While Loop: while loop has a controlling expression which must evaluate to a Booleanvalue. The loop body is repeatedly executed as long as the controlling expression evaluates to true.

var long song := invalid → songvar my music := media → songsvar num songs := my music → countvar i := 0while i < num songs and long song → is invalid dovar sng := my music → at(i)if sng→ duration > 10*60 thenlong song := sngelse// nothingi := i + 1

For Loop: The for loop in TouchDevelop is similar to for loops in other programming Languages, but with some added constraints. The index variable must be a Number; it must be initialized to zero for the first iteration and it must be incremented in steps of one.For Each Loop: A for each loop is used for iterating through all the elements of a collection.

ActionsActions are basically the function of other languages.An action can have zero or more input parameters and zero or more result parameters.

For example, consider the action Replicate defined as follows.action Replicate( s: String, n: Number ) returns r: Stringr := “”while n > 0 dor := r || sn := n – 1

The action can be invoked and its resulting value used in a statement like the following.

(“The answer is “ || ▷Replicate(“NO! “, 10) || “forever!”)→ post to wall

When an action is invoked, each result parameter is initialized to an invalid value of the correct type. When control reaches the end of the action, the final values of the result parameters are returned as the results of the call.

Calling a Library ActionAn action can be invoke action in a script which has been declare as library.Each such library script must be added to the library section of the script.

When editing code in the script, the editor provides a button labeled ♻libs.Tapping this key inserts the symbol ♻ into the code and the editor thenprovides a choice between the various names used for the imported libraryscripts. Once a name has been selected, the editor allows any action in thatlibrary script, other than those marked as private, to be called.

There is no direct access to any global data items or art items declared in the script.

Creating Library Scripts

While editing the property of a script tick to the check box option library converts the script in to library.A library script cannot define any entries in its Events or Records sections.

EventsEvents are like actions. They cannot be invoked they must invoke when some external action happens.It might be phone sensors, like shaking the phone or touch to a particular area.An event will interrupt the normal execution of a script.However an event will never interrupt the code for another event while it is still executing.

IMPORTANT WEBSITES• https://www.touchdevelop.com/app/#• http://research.microsoft.com/en-us/projects/touchdevelop/• https://www.touchdevelop.com/slides• https://www.touchdevelop.com/learn

REFERENCESREFERENCES 1. https://www.touchdevelop.com/book2. introduction to touchdevelop presentation at https://www.touchdevelop.com/slides