Connect IQ/Monkey C/変数 - api_programming @ ウィキ

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Content

http://developer.garmin.com/connect-iq/programmers-guide/monkey-c/

基本型

• Integers - 32-bit signed integers
• Floats - 32-bit floating point numbers
• Long – 64-bit signed integers
• Double – 64-bit floating point numbers
• Booleans - true and false
• Strings - strings of characters
• Objects – Instantiated objects (defined with the class keyword)
• Arrays - Allocated with the syntax new [X] where ‘X’ is an expression computing the size of the array
• Dictionaries - Associative arrays, allocated with the syntax {}

変数の宣言

varで宣言し、全ての値はオブジェクトとなる。

var n = null;               // Null reference
var x = 5;                  // 32-bit signed integers
var y = 6.0;                // 32-bit floating point
var l = 5l;                 // 64-bit signed integers
var d = 4.0d;               // 64-bit floating point
var bool = true;            // Boolean (true or false)
var arr = new [20 + 30];    // Array of size 50
var str = "Hello";          // String
var dict = { x=>y };        // Dictionary: key is 5, value is 6.0
var z = arr[2] + x;         // Null pointer waiting to happen

配列

宣言する用法は２つ
サイズを宣言

var array = new [size];

初期化をする

var array = [1, 2, 3, 4, 5];

多次元配列も可能

var array = [ [1,2], [3,4] ];

但し、空の２次元配列を直接宣言する方法がない。

// Shout out to all the Java programmers in the house
var array = new [first_dimension_size];

// Initialize the sub-arrays
for( var i = 0; i < first_dimension_size; i += 1 ) {
    array[i] = new [second_dimension_size];
}

辞書配列（連想配列）

var dict = { "a" => 1, "b" => 2 };  // Creates a dictionary

System.println( dict["a"] );        // Prints "1"
System.println( dict["b"] );        // Prints "2"
System.println( dict["c"] );        // Prints "null"

To initialize an empty dictionary, use the following syntax:

var x = {};                         // Empty dictionary

By default, objects hash on their reference value. Classes should override the hashCode() method in Toybox.Lang.Object to change the hashing function for their type:

class Person
{

   // Return a number as the hash code. Remember that the hash code must be
   // the same for two objects that are equal.
   // @return Hash code value
   function hashCode() {
       // Using the unique person id for the hash code
       return mPersonId;
   }

}

Dictionaries automatically resize and rehash as the contents grow or shrink. This makes them extremely flexible, but it comes at a cost. Insertion and removal of the contents can cause performance problems if there is accidental or excessive resizing and rehashing. Also, because hash tables require extra space for allocation, they are not as space-efficient as either objects or arrays.

シンボル(Symbols)

シンボル(Symbols)は軽量な定数識別子である。
Monkey Cではコンパイラが新たなシンボルを見つけたら、シンボルに固有の値を割り当てる。
これによりシンボルを、const or enumを宣言すること無く、キーや定数として使うことができる。

var a = :symbol_1;
var b = :symbol_1;
var c = :symbol_2;
Sys.println( a == b );  // Prints true
Sys.println( a == c );  // Prints false

enumを宣言せずにキーを作成したい時に便利

var person = { :firstName=>"Bob", :lastName=>"Jones" };

定数

Constants are named, immutable values declared with the const keyword. These are useful for storing unchanging values that may be used repeatedly throughout code. Constants must be declared at the module or class level; they cannot be declared within a function.

constで宣言する

Constants support the same types as listed for variables.

const PI = 3.14;
const EAT_BANANAS = true;
const BANANA_YELLOW = "#FFE135";

列挙型(Enumerations, enum)

列挙型は自動で1ずつ増加する値がマッピングされる。
Unless explicity set (see the second example), each proceeding symbol is automatically assigned the value of its predecessor plus one, starting with 0.
下記の例のように最初のシンボル(Monday)には0,次のシンボル(Tuesday)は1,となる。
These symbols can be used just like constant variables (which is essentially what they are). Enums must be declared at the module or class level; they cannot be declared within a function.

enum {
    Monday,   // Monday = 0
    Tuesday,  // Tuesday = 1
    Wednesday // Wednesday = 2
    // ...and so on
}

enum {
    x = 1337, // x = 1337
    y,        // y = 1338
    z,        // z = 1339
    a = 0,    // a = 0
    b,        // b = 1
    c         // c = 2
}

Note that assigning anything other than an integer will cause an error.
Calling Methods and Functions

To call a method within your own class or module, simply use the function call syntax:

function foo( a ) {

   //Assume foo does something really impressive

}

function bar() {

   foo( "hello" );

}

If calling on an instance of an object, precede the call with the object and a ‘.’.