time_machine 0.7.0

Date and time library for Flutter, Web, and Server with support for timezones, calendars, cultures, formatting and parsing.

Dart Time Machine

Time Machine is a date and time API for Dart (port of Noda Time). Time Machine is timezone aware and culture sensitive and runs on Flutter, Web, and Server.

Example Code:

// Sets up timezone and culture information
await TimeMachine.initialize();
print('Hello, ${DateTimeZone.local} from the Dart Time Machine!\n');

var tzdb = await DateTimeZoneProviders.tzdb;
var paris = await tzdb["Europe/Paris"];

var now = new Instant.now();

print('Basic');
print('UTC Time: $now');
print('Local Time: ${now.inLocalZone()}');
print('Paris Time: ${now.inZone(paris)}\n');

print('Formatted');
print('UTC Time: ${now.toString('dddd yyyy-MM-dd HH:mm')}');
print('Local Time: ${now.inLocalZone().toString('dddd yyyy-MM-dd HH:mm')}\n');

print('Formatted and French');
var culture = await Cultures.getCulture('fr-FR');
print('UTC Time: ${now.toString('dddd yyyy-MM-dd HH:mm', culture)}');
print('Local Time: ${
  now.inLocalZone().toString('dddd yyyy-MM-dd HH:mm', culture)}\n');

print('Parse French Formatted DateTimeZone');
// without the 'z' parsing will be forced to interpret the timezone as UTC
var localText = now
    .inLocalZone()
    .toString('dddd yyyy-MM-dd HH:mm z', culture);

var localClone = ZonedDateTimePattern
    .createWithCulture('dddd yyyy-MM-dd HH:mm z', culture)
    .parse(localText);
print(localClone.value);

VM

Flutter

Web (Dart2JS and DDC)

All unit tests pass on DartVM and DartWeb (just Chrome at this time). Tests have been run on preview versions of Dart2, but the focus is on DartStable, and they are not run before every pub publish. The public API is stabilizing -- mostly focusing on taking C# idiomatic code and making it Dart idiomatic code, so I wouldn't expect any over zealous changes. This is a preview release -- but, I'd feel comfortable using it. (Author Stamp of Approval!)

Documentation was ported, but some things changed for Dart and the documentation is being slowly updated (and we need an additional automated formatting pass).

Don't use any functions annotated with @internal. As of v0.3 you should not find any, but if you do, let me know.

Todo (before v1):

• Port Noda Time
• Unit tests passing in DartVM
• Dartification of the API
  • First pass style updates
  • Second pass ergonomics updates
  • Synchronous TZDB timezone provider
  • Review all I/O and associated classes and their structure
  • Simplify the API and make the best use of named constructors
• Non-Gregorian/Julian calendar systems
• Text formatting and Parsing
• Remove XML tags from documentation and format them for pub (human second pass still needed)
• Implement Dart4Web features
• Unit tests passing in DartWeb
• Fix DartDoc Formatting
• Create simple website with examples (at minimal a good set of examples under the examples directory)
• Rename Span (correlates to dart:core's Duration and is Duration in Noda Time).
  • Renamed to Time (denotatively correct, and maybe connotatively wrong, vs. all wrong -- it will grow on you)

External data: Timezones (TZDB via Noda Time) and Culture (ICU via BCL) are produced by a C# tool that is not included in this repository. The goal is to port all this functionality to Dart, the initial tool was created for bootstrapping -- and guaranteeing that our data is exactly the same thing that Noda Time would see (to ease porting).

Future Todo:

• Produce our own TSDB files
• Produce our own Culture files
• Benchmarking & Optimizing Library for Dart

Flutter Specific Notes

You'll need this entry in your pubspec.yaml.

# The following section is specific to Flutter.
flutter:
  assets:
    - packages/time_machine/data/cultures/cultures.bin
    - packages/time_machine/data/tzdb/tzdb.bin

Your initialization function will look like this:

import 'package:flutter/services.dart';

await TimeMachine.initialize(rootBundle);

Once flutter gets Isolate.resolvePackageUri functionality, we'll be able to merge VM and the Flutter code paths and no asset entry and no special import will be required. It would look just like the VM example.

DDC Specific Notes

class Foo {
  // Okay in Dart_VM 1.24 -- Okay in DartPad\Dart2JS
  // not Okay in DDC 1.24 -- Okay in DDC 2.0.0-dev63
  @override String toString([int x = 0, int y = 0, int z = 0]) 
    => '${x + y+ x}';
}

void main() {
  var foo = new Foo();
  print(foo.toString());
  print(foo.toString(1, 2, 3));
}

Overriding toString() with optional arguments doesn't work in DDC. We use this technique to provide optional formatting. Instant and ZonedDateTime currently have toStringDDC functions available. Still investigating potential solutions, but looks like waiting might be an okay algorithm, since it works in the newer DDC. I'm hoping Dart 2 stable launches soon.

toStringDDC instead of toStringFormatted to attempt to get a negative contagion coefficient. If you are writing on DartStable today and you need some extra string support because of this bug, let me know.