Added option to okBuck to configure rule overrides compatible with skylark

[romanoid]

Now instead of having to define java_library in DEFS one can tell okBuck to load and use my_java_library in //defs/my_defs.bzl like:

okbuck {
    ruleOverrides {
        override {
            nativeRuleName = "java_library"
            importLocation = "//defs/my_defs.bzl"
            newRuleName = "my_java_library"
        }
    }
}

with this config specified, generates files look like this:

load('//defs/my_defs.bzl', 'my_java_library')

my_java_library(
...

Description:

Related issue(s):

[kageiit]

Lets chat about a different api for this. Not a fan of the current verbosity

[raviagarwal7]

should probably be importLocation="//tooling/defs:my_defs.bzl.

nit: we should probably validate the file structure and also that new new rule name is all snake case?

[romanoid]

1. re-written documentation with full example instead of just single section

[raviagarwal7]

nit: can use streams

also, exported file rules append to buck files. Might have to consider creating a singleton which keeps track of all rules and writes them down in the end (similar to how dependencies are managed by DependencyManager)

[romanoid]

ack

[raviagarwal7]

some one off rules/buck files don't respect this rule type.

[romanoid]

thank you for letting me know, will have to identify these and update them in the breaking change.

[raviagarwal7]

nit: can use streams.

[romanoid]

I don't like throwing exceptions from the streams, stack traces tend to look strange.

[raviagarwal7]

might be a good idea to have these extensions implement an interface which initializes the extension. that can then be called by the base extension to validate & setup?

[romanoid]

This is good idea, will not do it yet, since there is only 2 precedents.

[raviagarwal7]

could probably just pass the okbuckExt

[romanoid]

sounds good.

[raviagarwal7]

seems like there is a cleaner way to do this - http://mrhaki.blogspot.com/2016/02/gradle-goodness-create-objects-with-dsl.html