Add "environment" parameter to spawnUri for String.fromEnvironment support.

sdk/lib/isolate/isolate.dart

Index: sdk/lib/isolate/isolate.dart
diff --git a/sdk/lib/isolate/isolate.dart b/sdk/lib/isolate/isolate.dart
index d5534ba71436bc0e4e10d6f12928165e9102b407..ec75fde7872d42b13d6e617f476460f4c35aa5ad 100644
--- a/sdk/lib/isolate/isolate.dart
+++ b/sdk/lib/isolate/isolate.dart
@@ -237,6 +237,15 @@ class Isolate {
    * WARNING: The [packageRoot] and [packages] parameters are not implemented
    * on all platforms yet.
    *
+   * The [environment] is a mapping from strings to strings which the
+   * spawned isolate uses when looking up [String.fromEnvironment] values.

[Siggi Cherem (dart-lang), 2015/09/17 17:06:57]

is this also meant to be used for the other `fromEnvironment` const constructors
(e.g. bool.fromEnvironment, int.fromEnvironment, etc)? Can we call them out too?

For a moment I was wondering if we wanted to switch the type to Map<String,
dynamic>, but I believe we still want to keep it as Map<String, String>, since
we don't know the type of the value until we see the const-constructor. In
particular, a flag like -Dfoo=true could be used in `const
String.fromEnvironment('foo') == 'true'` or in `const
bool.fromEnvironment('foo') == true`.

[floitsch, 2015/09/17 18:23:10]

This Map should be used for all X.fromEnvironment constructors. As you say: the
values are transformed at use site.

[Ivan Posva, 2015/09/17 21:55:20]

We do have a pretty good explanation on how the String is converted into the int
constants, but the description for bool is a bit lacking on that front. Maybe
that would lead to less user confusion and questions about the map being
String->String.

[Lasse Reichstein Nielsen, 2015/09/22 09:05:39]

I didn't write about int/bool.fromEnv because they are defined in terms of
String.fromEnv.

I'll add a "this is how it would be written using String.fromEnvironment" to the
bool.fromEnvironment docs as well, so it should be more clear that this is what
is happening.

+   * The system may add its own entries to environment as well.
+   * If `environment` is omitted, the spawned isolate has the same environment
+   * declarations as the spawning isolate.
+   *
+   * WARNING: The [environment] parameter is not implemented on all
+   * platforms yet.
+   *
    * Returns a future that will complete with an [Isolate] instance if the
    * spawning succeeded. It will complete with an error otherwise.
    */
@@ -250,7 +259,8 @@ class Isolate {
        Map<String, Uri> packages,
        bool errorsAreFatal,
        SendPort onExit,
-       SendPort onError});
+       SendPort onError,
+       Map<String, String> environment});

[Ivan Posva, 2015/09/17 21:55:20]

I find it interesting that the new parameter is added at the end here, but in
the middle of the existing parameters for the implementations. I am fine adding
it at any position that makes sense, but please be consistent.

[Lasse Reichstein Nielsen, 2015/09/22 09:05:39]

I've reordered them everywhere, so that the parameters corresponding to Isolate
methods are first and the ones corresponding to command line parameters are
last.

[Ivan Posva, 2015/09/22 09:56:59]

Thanks!

 
   /**
    * Requests the isolate to pause.