NON-BREAKING CHANGE: Lazy initialization has landed!
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Kasper Lund
Sep 14, 2012, 9:34:31 AM9/14/12
to General Dart Discussion
Dartisans,
We now have one of the major new language features of M1 implemented
across the board. That's right -- you can now use lazy initialization
for top-level and static variables (both final and non-final). This
means that the restriction that used to force the initialization
expression for such a variable to be a compile-time constant is no
more. You can now write:
final worklist = new Queue();
var compiler = new Compiler(worklist);
and both worklist and compiler will be initialized on first access.
We've also lifted the restriction for instance fields so the following
code now runs just fine:
class Cache {
final Map table = new Map();
...
}
as long as the initialization expressions do not refer to [this]. Such
expressions are evaluated when the object is created (not lazily on
first access as we do for static and top-level variables), but it cuts
down on the need for lengthy initializer lists in your constructors.
Cheers,
Kasper
We now have one of the major new language features of M1 implemented
across the board. That's right -- you can now use lazy initialization
for top-level and static variables (both final and non-final). This
means that the restriction that used to force the initialization
expression for such a variable to be a compile-time constant is no
more. You can now write:
final worklist = new Queue();
var compiler = new Compiler(worklist);
and both worklist and compiler will be initialized on first access.
We've also lifted the restriction for instance fields so the following
code now runs just fine:
class Cache {
final Map table = new Map();
...
}
as long as the initialization expressions do not refer to [this]. Such
expressions are evaluated when the object is created (not lazily on
first access as we do for static and top-level variables), but it cuts
down on the need for lengthy initializer lists in your constructors.
Cheers,
Kasper
Paul Brauner
Sep 14, 2012, 9:42:06 AM9/14/12
to General Dart Discussion
Awesome! I can now simplify the API of dart-enumerators.
On Fri, Sep 14, 2012 at 3:34 PM, Kasper Lund <kas...@google.com> wrote:
Dartisans,
We now have one of the major new language features of M1 implemented
across the board. That's right -- you can now use lazy initialization
for top-level and static variables (both final and non-final). This
means that the restriction that used to force the initialization
expression for such a variable to be a compile-time constant is no
more. You can now write:
final worklist = new Queue();
var compiler = new Compiler(worklist);
A very random example ;)
and both worklist and compiler will be initialized on first access.
We've also lifted the restriction for instance fields so the following
code now runs just fine:
class Cache {
final Map table = new Map();
...
}
as long as the initialization expressions do not refer to [this]. Such
expressions are evaluated when the object is created (not lazily on
first access as we do for static and top-level variables), but it cuts
down on the need for lengthy initializer lists in your constructors.
Cheers,
Kasper
--
Consider asking HOWTO questions at Stack Overflow: http://stackoverflow.com/tags/dart
John Evans
Sep 14, 2012, 11:12:18 AM9/14/12
to mi...@dartlang.org
Huzzah!! So happy about this! Great work Dart team.
Bob Nystrom
Sep 14, 2012, 12:49:33 PM9/14/12
to mi...@dartlang.org
On Fri, Sep 14, 2012 at 8:12 AM, John Evans <pru...@gmail.com> wrote:
Huzzah!! So happy about this! Great work Dart team.
Me too! :D
- bob
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