Update imports to use direct namespace imports

WARNING: OLD STYLE IMPORTS DO NOT WORK The old style of importing the
full module and using pb.* prefixes has been replaced with direct
imports of the needed names. This makes the code more explicit about
what is being used and removes the unnecessary pb prefix.

pythonbpf/codegen.py

@@ -6,8 +6,8 @@ from .maps_pass import maps_proc
 from .globals_pass import globals_processing
 import os
 import subprocess
-import pathlib
-import __main__
+import inspect
+from pathlib import Path
 
 def find_bpf_chunks(tree):
     """Find all functions decorated with @bpf in the AST."""
@@ -96,12 +96,14 @@ def compile_to_ir(filename: str, output: str):
     return output
 
 def compile():
-    main_file = pathlib.Path(__main__.__file__).resolve()
+    # Look one level up the stack to the caller of this function
+    caller_frame = inspect.stack()[1]
+    caller_file = Path(caller_frame.filename).resolve()
 
-    ll_file = pathlib.Path("/tmp") / main_file.with_suffix(".ll").name
-    o_file = main_file.with_suffix(".o")
+    ll_file = Path("/tmp") / caller_file.with_suffix(".ll").name
+    o_file = caller_file.with_suffix(".o")
 
-    compile_to_ir(str(main_file), str(ll_file))
+    compile_to_ir(str(caller_file), str(ll_file))
 
     subprocess.run([
         "llc", "-march=bpf", "-filetype=obj", "-O2",