Add a Python command-line interface (#441)

* In Python, delete the temporary file by default

* Add a Python command-line interface

* Apply style fixes

Signed-off-by: Ian Hunter <ian.hunter@intel.com>

* more style fixes

* fix trailing whitespace

---------

Signed-off-by: Ian Hunter <ian.hunter@intel.com>
Co-authored-by: Ian Hunter <ian.hunter@intel.com>

README.md

@@ -83,6 +83,15 @@ roll("1d20")
 # (return code, final result, dice breakdown (if enabled))
 ```
 
+Or, use the command-line interface (see `--help`):
+```sh
+$ python3 -m gnoll 2d4
+6
+$ function gnoll() { python3 -m gnoll --breakdown "$@" ; }
+$ gnoll 3d6 + 10
+[5, 5, 4] --> 24
+```
+
 ### 🛠️ Installing From Source
 #### Basic Requirements
 ```bash

src/python/code/gnoll/__init__.py

@@ -48,20 +48,18 @@ def roll(s,
          mock=None,
          mock_const=3,
          breakdown=False,
-         builtins=False):
+         builtins=False,
+         keep_temp_file=False):
     """Parse some dice notation with GNOLL.
     @param s the string to parse
     @param verbose whether to enable verbosity (primarily for debug)
     @param mock override the internal random number generator (for testing).
     @param mock_const the seed value for overriding with mocks
     @param breakdown get the details of each dice rolled, not just the final result
+    @param keep_temp_file don't delete the temporary file
     @param force_dll_reload destroy the dll/shared object and reload (inadvisable)
     @return  return code, final result, dice breakdown (None if disabled)
     """
-    temp = tempfile.NamedTemporaryFile(prefix="gnoll_roll_",
-                                       suffix=".die",
-                                       delete=False)
-
     def make_native_type(v):
         """
         Change a string to a more appropriate type if possible.
@@ -87,36 +85,48 @@ def extract_from_dice_file(lines, seperator):
         v = [list(map(make_native_type, x)) for x in v]
         return v
 
-    die_file = temp.name
-    os.remove(die_file)
+    try:
+        temp = tempfile.NamedTemporaryFile(prefix="gnoll_roll_",
+                                           suffix=".die",
+                                           delete=False)
+        temp.close()
+
+        die_file = temp.name
+
+        out_file = str(die_file).encode("ascii")
+        if verbose:
+            print("Rolling: ", s)
+            print("Output in:", out_file)
+
+        s = s.encode("ascii")
 
-    out_file = str(die_file).encode("ascii")
-    if verbose:
-        print("Rolling: ", s)
-        print("Output in:", out_file)
+        return_code = libc.roll_full_options(
+            s,
+            out_file,
+            verbose,  # enable_verbose
+            breakdown,  # enable_introspect
+            mock is not None,  # enable_mock
+            builtins,  # enable_builtins
+            mock,
+            mock_const,
+        )
+        if return_code != 0:
+            raise_gnoll_error(return_code)
 
-    s = s.encode("ascii")
+        with open(out_file, encoding="utf-8") as f:
+            lines = f.readlines()
 
-    return_code = libc.roll_full_options(
-        s,
-        out_file,
-        verbose,  # enable_verbose
-        breakdown,  # enable_introspect
-        mock is not None,  # enable_mock
-        builtins,  # enable_builtins
-        mock,
-        mock_const,
-    )
-    if return_code != 0:
-        raise_gnoll_error(return_code)
+        dice_breakdown = extract_from_dice_file(lines, ",")
+        result = extract_from_dice_file(lines, ";")
 
-    with open(out_file, encoding="utf-8") as f:
-        lines = f.readlines()
+        return int(return_code), result, dice_breakdown
 
-    dice_breakdown = extract_from_dice_file(lines, ",")
-    result = extract_from_dice_file(lines, ";")
+    finally:
+        if not keep_temp_file:
+            if verbose:
+                print("Deleting:", out_file)
 
-    return int(return_code), result, dice_breakdown
+            os.remove(die_file)
 
 
 if __name__ == "__main__":

src/python/code/gnoll/__main__.py

@@ -0,0 +1,92 @@
+"""Roll some dice with GNOLL."""
+
+import sys
+import argparse
+import gnoll
+
+
+def parse_cmdline_args(args):
+    """Extract values from the commandline
+    @param args - the arguments from the commandline (excluding the python3 call)
+    """
+    p = argparse.ArgumentParser(
+        description=__doc__,
+        usage='python3 -m gnoll [options] EXPR',
+        add_help=False)
+
+    p.add_argument(
+        'EXPR',
+        nargs='+',
+        help='a dice expression to evaluate'
+             '(multiple arguments will be joined with spaces)'
+    )
+
+    g = p.add_argument_group('main options')
+    g.add_argument(
+        '-h',
+        '--help',
+        action='help',
+        help='show this help message and exit'
+    )
+    g.add_argument(
+        '-b',
+        '--breakdown',
+        action='store_true',
+        help='show a breakdown into individual dice'
+    )
+    g.add_argument(
+        '--no-builtins',
+        action='store_true',
+        help='disable built-in macros'
+    )
+
+    g = p.add_argument_group('debugging options')
+    g.add_argument(
+        '-v',
+        '--verbose',
+        action='store_true',
+        help='enable verbosity'
+    )
+    g.add_argument(
+        '--keep-temp-file',
+        action='store_true',
+        help="don't delete the created temporary file"
+    )
+    g.add_argument(
+        '--mock',
+        metavar='TYPE',
+        type=int,
+        help='mocking type'
+    )
+    g.add_argument(
+        '--mock-const',
+        metavar='N',
+        type=int,
+        default=3,
+        help='mocking constant'
+    )
+
+    a = p.parse_args(args)
+    a.EXPR = ' '.join(a.EXPR)
+    return a
+
+
+def main(EXPR, no_builtins, **kwargs):
+    """
+    The entry point for gnoll when called via `python -m gnoll`
+    @param EXPR - the expression
+    @param no_builtins - a flag to disable builtins
+    @param **kwargs - other key word arguments to be passed to gnoll.roll
+    """
+    _, [[result]], breakdown = gnoll.roll(
+        EXPR,
+        builtins=not no_builtins,
+        **kwargs)
+    if breakdown:
+        print(breakdown[0], '-->', result)
+    else:
+        print(result)
+
+
+if __name__ == '__main__':
+    main(**vars(parse_cmdline_args(sys.argv[1:])))