- Implement a first cut for const String.env in the VM to allow

sdk/lib/core/int.dart

Index: sdk/lib/core/int.dart
===================================================================
--- sdk/lib/core/int.dart	(revision 28427)
+++ sdk/lib/core/int.dart	(working copy)
@@ -252,4 +252,12 @@
   external static int parse(String source,
                             { int radix,
                               int onError(String source) });
+
+  /**
+   * Returns the integer value for the given environment variable [name] or [defaultValue]

[Lasse Reichstein Nielsen, 2013/10/10 07:45:03]

Long lines.

[Ivan Posva, 2013/10/11 16:22:11]

You are commenting on a revision that was only uploaded as a checkpoint to move
between machines. Thanks for you suggestions nonetheless.

-Ivan

+   * if [name] is not present. If the value of the environment variable is not a valid

[Lasse Reichstein Nielsen, 2013/10/10 07:45:03]

I'd prefer to use defaultValue if the environment variable exists, but is not a
valid integer? Seems more consistent, since it's the way to avoid a
formatException that you can't check for.

It's not unprecedented that at const constructor throws (q.v. Symbol), but it's
still a little iffy (then it's a *compile time error* to do 'const int("x")' if
the env contains a value for "x" that isn't an integer).

Try making the first sentence shorter (base operation, no exceptions), and
elaborate in a second paragraph. Something like:

/**
 * Returns the integer value with the name [name] in the system
 * environment.
 *
 * If the environment does not contain an entry called [name],
 * the [defaultValue] is returned instead.
 * 
 * Throws a [FormatException] if the environment contains an entry
 * called `name` with a value that isn't an integer value.
 */

+   * integer literal a [FormatException] is thrown.
+   */
+  external const factory int.fromEnvironment(String name,
+                                             {int defaultValue: 0});
 }