Environment

JRuby, all versions.

Expected Behavior

In MRI, ENV is not a Hash but a pseudo-Hash-like singleton object with all of its own methods. This is done so that all Hash-y operations actually go directly to and from the system environment via getenv and setenv.

Actual Behavior

In JRuby, we have the following differences:

• ENV is a subclass of Hash
• ENV overrides a few Hash methods to handle case-insensitivity, ArgumentError: string contains null byte #3907 PATH encoding, and so on.
• ENV is populated at boot by first creating a Map of RubyString, and then by inserting that Map's contents into ENV itself.

This allows us to delegate some of ENV's logic to Hash, but also results in a lot of needless complexity and a visible difference from MRI.

In the case of ENV_JAVA, we do basically the same process, when we really could just go directly to/from System.getProperty/setProperty.

I propose that we fix this in a 9k release by making ENV truly just be a proxy as in MRI.

There is one possible side effect of following MRI's course: We would not cache the Ruby String instances that ENV produces, and would have to transcode to/from Java String to interact with env and property APIs.