Kami mempersembahkan kepada Anda terjemahan dari artikel yang mengumumkan rilis Dart 2.12. Ya, kami tahu bahwa kami sangat terlambat dengan publikasi: aslinya dirilis pada 3 Maret. Namun, Dart 2.12 adalah rilis penting dan kami memutuskan untuk mempostingnya.
Dart 2.12 dirilis. Ini berisi versi stabil dari keamanan nol suara dan Dart FFI .
Keamanan nol adalah fitur skala besar terbaru kami. Tujuannya adalah untuk meningkatkan kinerja: untuk membantu Anda menghindari kesalahan nol. Masalah yang disebabkan oleh kesalahan ini seringkali sulit ditemukan dalam kode Anda. Kami membicarakan hal ini secara mendetail di video pengantar .
FFI adalah mekanisme interoperabilitas yang memungkinkan Anda memanggil kode C. Misalnya, mengakses Windows Win32 API . Dart 2.12 sudah tersedia.
Fungsionalitas unik dari platform tempat Dart dijalankan
sound null safety FFI, , Dart. . , web. .
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hot reload
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. :
final int major = version?.major;
final int minor = version?.minor;
if (globals.platform.isMacOS) {
// plugin path of Android Studio changed after version 4.1.
if (major >= 4 && minor >= 1) {
...
final int major = version?.major; final int minor = version?.minor; if (globals.platform.isMacOS) { // plugin path of Android Studio changed after version 4.1. if (major >= 4 && minor >= 1) { ... ? version
null, major
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// In null-safe Dart, none of these can ever be null.
var i = 42; // Inferred to be an int.
String name = getFileName();
final b = Foo();
, null, , ? :
// aNullableInt can hold either an integer or null.
int? aNullableInt = null;
Null safety : nullable . , null, Dart nullable non-nullable:
int definitelyInt(int? aNullableInt) {
if (aNullableInt == null) {
return 0;
}
// aNullableInt has now promoted to a non-null int.
return aNullableInt;
}
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Dart FFI Dart C
Dart FFI C , C , . Dart 2.12, Dart FFI - . , (struct) .
C , . FFI , Dart 2.12 . C, , :
struct Link {
double value;
Link* next;
};
void MoveByReference(Link* link) {
link->value = link->value + 10.0;
}
Coord MoveByValue(Link link) {
link.value = link.value + 10.0;
return link;
}
C API . . :
struct Wheel {
int spokes;
};
struct Bike {
struct Wheel front;
struct Wheel rear;
int buildYear;
};
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// Allocate a pointer to an Utf8 array, fill it from a Dart string,
// pass it to a C function, convert the result, and free the arg.
//
// Before API change:
final pointer = allocate<Int8>(count: 10);
free(pointer);
final arg = Utf8.toUtf8('Michael');
var result = helloWorldInC(arg);
print(Utf8.fromUtf8(result);
free(arg);
// After API change:
final pointer = calloc<Int8>(10);
calloc.free(pointer);
final arg = 'Michael'.toNativeUtf8();
var result = helloWorldInC(arg);
print(result.toDartString);
calloc.free(arg);
FFI
API , Dart , C. , , FFI C. , : package:ffigen.
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, FFI , FFI , . :
FFI
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open_file API, . FFI API (Windows, macOS Linux).
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Dart 2.12
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, pub.dev, , sound null safety. null safety, , .
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sound null safety FFI. , : @dart_lang.