Add bin/python that mimics Python CLI

.gitignore

@@ -1,3 +1,4 @@
 deps/deps.jl
 deps/PYTHON
 deps/build.log
+*.pyc

bin/python

@@ -0,0 +1,28 @@
+#!/usr/bin/env julia
+
+description = """
+Python interpreter inside a Julia process.
+
+This command line interface mimics a basic subset of Python program so that
+Python program involving calls to Julia functions can be run without setting
+up PyJulia (which is currently hard for some platforms).
+
+Although this script has -i option and it can do a basic REPL, contrl-c may
+crash the whole process.  Consider using IPython >= 7 which can be launched by:
+
+    python -m IPython
+"""
+
+using PyCall
+
+# Initialize julia.Julia once so that subsequent calls of julia.Julia()
+# uses pre-configured DLL.
+pyimport("julia")[:Julia](init_julia=false)
+
+pushfirst!(PyVector(pyimport("sys")["path"]),
+           joinpath(dirname(dirname(pathof(PyCall))), "lib"))
+
+code = pyimport("pseudo_python_cli")[:main](ARGS, description)
+if code isa Integer
+    exit(code)
+end

lib/pseudo_python_cli.py

@@ -0,0 +1,132 @@
+'''
+Pseudo Python command line interface.
+
+It tries to mimic a subset of Python CLI:
+https://docs.python.org/3/using/cmdline.html
+'''
+
+import argparse
+import code
+import runpy
+import sys
+import traceback
+
+
+def python(module, command, script, script_args, interactive):
+    if command:
+        sys.argv[0] = "-c"
+    elif script:
+        sys.argv[0] = script
+    sys.argv[1:] = script_args
+
+    banner = ""
+    try:
+        if command:
+            scope = {}
+            exec(command, scope)
+        elif module:
+            scope = runpy.run_module(
+                module,
+                run_name="__main__",
+                alter_sys=True)
+        elif script == "-":
+            source = sys.stdin.read()
+            exec(compile(source, "<stdin>", "exec"), scope)
+        elif script:
+            scope = runpy.run_path(
+                script,
+                run_name="__main__")
+        else:
+            interactive = True
+            scope = None
+            banner = None  # show banner
+    except Exception:
+        if not interactive:
+            raise
+        traceback.print_exc()
+
+    if interactive:
+        code.interact(banner=banner, local=scope)
+
+
+class CustomFormatter(argparse.RawDescriptionHelpFormatter,
+                      argparse.ArgumentDefaultsHelpFormatter):
+    pass
+
+
+def make_parser(description=__doc__):
+    parser = argparse.ArgumentParser(
+        prog=None if sys.argv[0] else "python",
+        usage="%(prog)s [option] ... [-c cmd | -m mod | script | -] [args]",
+        formatter_class=CustomFormatter,
+        description=description)
+
+    parser.add_argument(
+        "-i", dest="interactive", action="store_true",
+        help='''
+        inspect interactively after running script.
+        ''')
+
+    group = parser.add_mutually_exclusive_group()
+    group.add_argument(
+        "-c", dest="command",
+        help='''
+        Execute the Python code in COMMAND.
+        ''')
+    group.add_argument(
+        "-m", dest="module",
+        help='''
+        Search sys.path for the named MODULE and execute its contents
+        as the __main__ module.
+        ''')
+
+    parser.add_argument(
+        "script", nargs="?",
+        help="path to file")
+
+    return parser
+
+
+def split_args(args):
+    '''
+    Split arguments to Python and `sys.argv[1:]`.
+    '''
+    it = iter(args)
+    py_args = []
+    for a in it:
+        if a in ("-c", "-m"):
+            py_args.append(a)
+            try:
+                a = next(it)
+            except StopIteration:
+                break
+            py_args.append(a)
+            break
+        elif a == "-":
+            py_args.append(a)
+            break
+        elif a.startswith("-"):
+            py_args.append(a)
+        else:  # script
+            py_args.append(a)
+            break
+    return py_args, list(it)
+
+
+def main(args=None, description=__doc__):
+    if args is None:
+        args = sys.argv[1:]
+    parser = make_parser(description=description)
+    py_args, script_args = split_args(args)
+    try:
+        ns = parser.parse_args(py_args)
+        python(script_args=script_args, **vars(ns))
+    except SystemExit as err:
+        return err.code
+    except Exception:
+        traceback.print_exc()
+        return 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())