simplify design a bit

Author: philsc

python/bin/BUILD.bazel

@@ -27,7 +27,7 @@ label_flag(
 
 generate_repl_main(
     name = "repl_py",
-    src = "repl_stub.py",
+    src = "repl_stub",
     out = "repl.py",
 )
 
@@ -50,9 +50,13 @@ py_binary(
     name = "repl",
     srcs = [":repl.py"],
     visibility = ["//visibility:public"],
+    data = [
+        ":repl_stub",
+    ],
     deps = [
         ":repl_dep",
         ":repl_stub_dep",
+        "//python/runfiles",
     ],
 )
 

python/private/repl.bzl

@@ -1,19 +1,13 @@
 def _generate_repl_main_impl(ctx):
-    args = ctx.actions.args()
-    args.add_all([
-        ctx.file._template,
-        ctx.file.src,
-        ctx.outputs.out,
-    ])
+    stub_repo = ctx.attr.src.label.repo_name or ctx.workspace_name
+    stub_path = "/".join([stub_repo, ctx.file.src.short_path])
 
-    ctx.actions.run(
-        executable = ctx.executable._generator,
-        inputs = [
-            ctx.file._template,
-            ctx.file.src,
-        ],
-        outputs = [ctx.outputs.out],
-        arguments = [args],
+    ctx.actions.expand_template(
+        template = ctx.file._template,
+        output = ctx.outputs.out,
+        substitutions = {
+            "%stub_path%": stub_path,
+        },
     )
 
 generate_repl_main = rule(

python/private/repl_main_generator.py

@@ -1,9 +1,11 @@
 import os
+import runpy
 from pathlib import Path
 
+from python.runfiles import runfiles
 
-def repl_stub():
-    pass  # %REPLACE_WHOLE_LINE_WITH_STUB%
+
+STUB_PATH = "%stub_path%"
 
 
 def start_repl():
@@ -19,7 +21,8 @@ def start_repl():
             compiled_code = compile(source_code, filename=startup_file, mode="exec")
             eval(compiled_code, {})
 
-    repl_stub()
+    bazel_runfiles = runfiles.Create()
+    runpy.run_path(bazel_runfiles.Rlocation(STUB_PATH), run_name="__main__")
 
 
 if __name__ == "__main__":