PlatformServices abstract

abstractclassPlatformServices

Abstract interface for platform-specific services.

This allows LuaDardo to run on both native and web platforms by abstracting away dart:io dependencies.

Implementers

• NativePlatformServices

Constructors

PlatformServices()

PlatformServices()

Properties

hashCode no setter inherited

intgethashCode

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

Implementation

external int get hashCode;

isNative no setter

boolgetisNative

Whether this is running on a native platform.

Implementation

bool get isNative => !isWeb;

isWeb no setter

boolgetisWeb

Whether this is running on a web platform.

Implementation

bool get isWeb;

pathSeparator no setter

StringgetpathSeparator

Get the platform's path separator.

Implementation

String get pathSeparator;

printCallback read / write

voidFunction(String)printCallback

getter:

Custom print callback. Can be overridden to redirect output.

setter:

Custom print callback. Can be overridden to redirect output.

Implementation

void Function(String) printCallback = _defaultPrintCallback;

runtimeType no setter inherited

TypegetruntimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation

external Type get runtimeType;

supportsFileSystem no setter

boolgetsupportsFileSystem

Whether file system operations are supported.

Implementation

bool get supportsFileSystem;

supportsProcess no setter

boolgetsupportsProcess

Whether process operations are supported.

Implementation

bool get supportsProcess;

Methods

defaultPrint()

voiddefaultPrint(Strings)

Print a string using the default mechanism for this platform.

Implementation

void defaultPrint(String s);

deleteFile()

booldeleteFile(Stringpath)

Delete a file at the given path. Returns true if successful, false otherwise.

Implementation

bool deleteFile(String path);

directoryExists()

booldirectoryExists(Stringpath)

Check if a directory exists at the given path.

Implementation

bool directoryExists(String path);

exit()

Neverexit(intcode)

Exit the application with the given code. Throws UnsupportedError on platforms that don't support this.

Implementation

Never exit(int code);

fileExists()

boolfileExists(Stringpath)

Check if a file exists at the given path.

Implementation

bool fileExists(String path);

getEnvironmentVariable()

String?getEnvironmentVariable(Stringname)

Get an environment variable value. Returns null if not available or not supported on this platform.

Implementation

String? getEnvironmentVariable(String name);

noSuchMethod() inherited

dynamicnoSuchMethod(Invocationinvocation)

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

Implementation

@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

println()

voidprintln(Strings)

Print a string followed by a newline.

Implementation

void println(String s) {
  printCallback(s);
  printCallback('\n');
}

readFileAsBytes()

Uint8List?readFileAsBytes(Stringpath)

Read a file as bytes. Returns null if file doesn't exist or reading fails.

Implementation

Uint8List? readFileAsBytes(String path);

readFileAsString()

String?readFileAsString(Stringpath)

Read a file as a string. Returns null if file doesn't exist or reading fails.

Implementation

String? readFileAsString(String path);

renameFile()

boolrenameFile(StringoldPath,StringnewPath)

Rename a file from oldPath to newPath. Returns true if successful, false otherwise.

Implementation

bool renameFile(String oldPath, String newPath);

runProcess()

int?runProcess(Stringcommand,List<String>args)

Run a process synchronously. Returns the exit code, or null if not supported.

Implementation

int? runProcess(String command, List<String> args);

toString() inherited

StringtoString()

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from Object.

Implementation

external String toString();

Operators

operator ==() inherited

booloperator ==(Objectother)

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

• Total: It must return a boolean for all arguments. It should never throw.

• Reflexive: For all objects o, o == o must be true.

• Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

• Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

Implementation

external bool operator ==(Object other);

Static Properties

instance no setter

PlatformServicesgetinstance

Get the singleton instance of platform services. Automatically initializes if not already done.

Implementation

static PlatformServices get instance {
  _instance ??= platform_impl.createPlatformServices();
  // Initialize printCallback to use defaultPrint on first access
  if (_instance!.printCallback == _defaultPrintCallback) {
    _instance!.printCallback = _instance!.defaultPrint;
  }
  return _instance!;
}

Static Methods

init()

voidinit(PlatformServicesservices)

Initialize the platform services with a custom implementation. This is optional - if not called, a default implementation will be used.

Implementation

static void init(PlatformServices services) {
  _instance = services;
}

reset()

voidreset()

Reset the platform services instance (useful for testing).

Implementation

static void reset() {
  _instance = null;
}