Add experimental exec command (#4)

BUILD.bazel

@@ -36,6 +36,7 @@ go_library(
         "//command/release:go_default_library",
         "//command/targets:go_default_library",
         "//command/use:go_default_library",
+        "//command/exec:go_default_library",
         "@com_github_urfave_cli//:go_default_library",
     ],
 )

Makefile

@@ -10,7 +10,7 @@ release: install
 	bazel release \
 	--owner bzl-io \
 	--repo bzl \
-	--tag v0.1.6 \
+	--tag v0.1.7 \
 	--notes RELEASE.md \
 	--commit $(HEAD) \
 	//:bzl

README.md

@@ -218,3 +218,16 @@ Print linting issues in build files (buildifier).
 ### `$ bazel fmt`
 
 Fix formatting issues in build files (buildifier).
+
+### `$ bazel exec`
+
+Similar to `bazel run` but without running in the sandbox, useful when you don't
+want to use `bazel run` and may not be able to easily predict the name of the
+output binary.
+
+For example, the following are largely equivalent:
+
+```
+$ bazel build //:bzl && ./bazel-bin/linux_amd64_stripped/bzl
+$ bazel exec //:bzl
+```

app.go

@@ -8,6 +8,7 @@ import (
 	"github.com/urfave/cli"
 
 	"github.com/bzl-io/bzl/bazelutil"
+	"github.com/bzl-io/bzl/command/exec"
 	fmtcmd "github.com/bzl-io/bzl/command/fmt"
 	"github.com/bzl-io/bzl/command/install"
 	"github.com/bzl-io/bzl/command/release"
@@ -54,6 +55,7 @@ func NewApp() *App {
 
 	// Add commands
 	app.Commands = []cli.Command{
+		*exec.Command,
 		*install.Command,
 		*release.Command,
 		*use.Command,

command/use/use.go

@@ -241,6 +241,8 @@ func execute(c *cli.Context) error {
 	switch rule {
 	case "http_archive":
 		printHttpArchive(wsName, owner, repo, tag, sha256, archiveType)
+	case "go_repository":
+		printGoRepository(wsName, owner, repo, tag, sha256)
 	default:
 		return fmt.Errorf("Unknown --rule=%q", rule)
 	}
@@ -292,3 +294,19 @@ http_archive(
 
 `, wsName, owner, repo, tag, archiveType, stripPrefix, sha256)
 }
+
+func printGoRepository(wsName, owner, repo, tag, sha256 string) {
+	attr := "tag"
+	if len(tag) == 40 {
+		attr = "commit"
+	}
+	fmt.Printf(`
+go_repository(
+    name = %q,
+    importpath = "github.com/%s/%s",
+    %s = %q,
+    sha256 = %q,
+)
+
+`, wsName, owner, repo, attr, tag, sha256)
+}