move from time check to backup as file safety strategy

Author: JohnMount

coverage.txt

@@ -1,5 +1,5 @@
 ============================= test session starts ==============================
-platform darwin -- Python 3.9.7, pytest-6.2.5, py-1.11.0, pluggy-1.0.0
+platform darwin -- Python 3.9.12, pytest-7.1.1, pluggy-1.0.0
 rootdir: /Users/johnmount/Documents/work/wvpy/pkg
 plugins: anyio-3.5.0, cov-3.0.0
 collected 20 items
@@ -19,16 +19,26 @@ tests/test_stats1.py .                                                   [ 90%]
 tests/test_threshold_stats.py .                                          [ 95%]
 tests/test_typs_in_frame.py .                                            [100%]
 
----------- coverage: platform darwin, python 3.9.7-final-0 -----------
+=============================== warnings summary ===============================
+../../../../opt/anaconda3/envs/research_env/lib/python3.9/site-packages/seaborn/rcmod.py:82
+  /Users/johnmount/opt/anaconda3/envs/research_env/lib/python3.9/site-packages/seaborn/rcmod.py:82: DeprecationWarning: distutils Version classes are deprecated. Use packaging.version instead.
+    if LooseVersion(mpl.__version__) >= "3.0":
+
+../../../../opt/anaconda3/envs/research_env/lib/python3.9/site-packages/setuptools/_distutils/version.py:351
+  /Users/johnmount/opt/anaconda3/envs/research_env/lib/python3.9/site-packages/setuptools/_distutils/version.py:351: DeprecationWarning: distutils Version classes are deprecated. Use packaging.version instead.
+    other = LooseVersion(other)
+
+-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
+
+---------- coverage: platform darwin, python 3.9.12-final-0 ----------
 Name                      Stmts   Miss  Cover
 ---------------------------------------------
 wvpy/__init__.py              3      0   100%
 wvpy/jtools.py              146     32    78%
-wvpy/pysheet.py              79     79     0%
+wvpy/pysheet.py              89     89     0%
 wvpy/render_workbook.py      47     47     0%
 wvpy/util.py                321      7    98%
 ---------------------------------------------
-TOTAL                       596    165    72%
-
+TOTAL                       606    175    71%
 
-============================= 20 passed in 14.28s ==============================
+======================= 20 passed, 2 warnings in 16.87s ========================

pkg/build/lib/wvpy/pysheet.py

@@ -5,13 +5,14 @@
 
 import argparse
 import os
+import shutil
 import sys
 import traceback
 from wvpy.jtools import convert_py_file_to_notebook, convert_notebook_file_to_py
 
 
 def main() -> int:
-    parser = argparse.ArgumentParser(description="Convert between .py and .ipynb (can have suffix, or guess suffix)")
+    parser = argparse.ArgumentParser(description="Convert between .py and .ipynb or back (can have suffix, or guess suffix)")
     parser.add_argument('--quiet', action='store_true', help='delete input file')
     parser.add_argument('--delete', action='store_true', help='delete input file')
     parser.add_argument(
@@ -26,67 +27,79 @@ def main() -> int:
     assert len(set(args.infile)) == len(args.infile)
     assert isinstance(args.quiet, bool)
     assert isinstance(args.delete, bool)
+    # set up the work request
+    base_names_seen = set()
     input_suffices_seen = set()
     tasks = []
     other_suffix = {'.py': '.ipynb', '.ipynb': '.py'}
     for input_file_name in args.infile:
         assert isinstance(input_file_name, str)
         assert len(input_file_name) > 0
-        suffix_seen = 'error'  # placeholder
+        suffix_seen = 'error'  # placeholder/sentinel
+        base_name = input_file_name
         if input_file_name.endswith('.py'):
             suffix_seen = '.py'
+            base_name = input_file_name.removesuffix(suffix_seen)
         elif input_file_name.endswith('.ipynb'):
             suffix_seen = '.ipynb'
+            base_name = input_file_name.removesuffix(suffix_seen)
         else:
             py_exists = os.path.exists(input_file_name + '.py')
             ipynb_exists = os.path.exists(input_file_name + '.ipynb')
             if py_exists == ipynb_exists:
-                raise ValueError("if no suffix is specified, then exactly one of the .py or ipynb file forms must be present")
+                raise ValueError(f'{base_name}: if no suffix is specified, then exactly one of the .py or ipynb file forms must be present')
             if py_exists:
                 suffix_seen = '.py'
             else:
                 suffix_seen = '.ipynb'
             input_file_name = input_file_name + suffix_seen
-        assert suffix_seen in other_suffix.keys()
-        input_suffices_seen.add(suffix_seen)
-        if len(input_suffices_seen) != 1:
-            raise ValueError(f"saw more than one input suffix: {input_suffices_seen}")
         assert os.path.exists(input_file_name)
-        output_file_name = input_file_name.removesuffix(suffix_seen) + other_suffix[suffix_seen]
-        if os.path.exists(output_file_name):
-            if os.path.getmtime(output_file_name) > os.path.getmtime(input_file_name):
-                raise ValueError(f"output {output_file_name} is already newer than input f{input_file_name}")
+        assert suffix_seen in other_suffix.keys()  # expected suffix
+        assert base_name not in base_names_seen  # each base file name only used once
+        base_names_seen.add(base_name)
+        input_suffices_seen.add(suffix_seen)
+        if len(input_suffices_seen) != 1:    # only one direction of conversion in batch job
+            raise ValueError(f"conversion job may only have one input suffix: {input_suffices_seen}")
+        output_file_name = base_name + other_suffix[suffix_seen]
         tasks.append((input_file_name, output_file_name))
-    if len(input_suffices_seen) != 1:
-        raise ValueError(f"expected only one input suffix: {input_suffices_seen}")
     # do the work
     for input_file_name, output_file_name in tasks:
+        if not args.quiet:
+            print(f'from "{input_file_name}" to "{output_file_name}"')
+        # back up result target if present
+        if os.path.exists(output_file_name):
+            output_backup_file = f'{output_file_name}~'
+            if not args.quiet:
+                print(f'   copying previous output target "{output_file_name}" to "{output_backup_file}"')
+            shutil.copy2(output_file_name, output_backup_file)
+        # convert
         if input_file_name.endswith('.py'):
             if not args.quiet:
-                print(f"converting {input_file_name} to {output_file_name}")
+                print(f"   converting Python {input_file_name} to Jupyter notebook {output_file_name}")
             convert_py_file_to_notebook(
                 py_file=input_file_name,
                 ipynb_file=output_file_name,
             )
         elif input_file_name.endswith('.ipynb'):
             if not args.quiet:
-                print(f"converting {input_file_name} to {output_file_name}")
+                print(f'   converting Jupyter notebook "{input_file_name}" to Python "{output_file_name}"')
             convert_notebook_file_to_py(
                 ipynb_file=input_file_name,
                 py_file=output_file_name)
         else:
             raise ValueError("input file name must end with .py or .ipynb")
-    # do any deletions
-    if args.delete:
-        for input_file_name, output_file_name in tasks:
+        # do any deletions
+        if args.delete:
             input_backup_file = f'{input_file_name}~'
             if not args.quiet:
-                print(f"moving {input_file_name} to {input_backup_file}")
+                print(f"   moving input {input_file_name} to {input_backup_file}")
             try:
                 os.remove(input_backup_file)
             except FileNotFoundError:
                 pass
             os.rename(input_file_name, input_backup_file)
+        if not args.quiet:
+            print()
     return 0