allow binary file objects to be passed to load() and dump()

Author: Ken Kundert

doc/conf.py

@@ -3,7 +3,7 @@
 # General
 
 project = u'NestedText'
-copyright = u'2020-2024, Ken and Kale Kundert'
+copyright = u'2020-2025, Ken and Kale Kundert'
 release = '3.7'
 version = '.'.join(release.split('.'))
 

doc/releases.rst

@@ -16,6 +16,8 @@ Latest development version
 | Version: 3.7
 | Released: 2024-04-27
 
+- Allow binary files to be passed to :func:`load()` and :func:`dump()`.
+
 
 v3.7 (2024-04-27)
 -----------------

nestedtext/nestedtext.py

@@ -12,7 +12,7 @@
 """
 
 # MIT License {{{1
-# Copyright (c) 2020-2024 Ken and Kale Kundert
+# Copyright (c) 2020-2025 Ken and Kale Kundert
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -338,6 +338,11 @@ def read_lines(self):
         for lineno, line in enumerate(self.lines):
             key = None
             value = None
+            try:
+                # decode to utf8 if a byte string or binary file is given
+                line = line.decode('utf8')
+            except AttributeError:
+                pass
             line = line.rstrip("\n")
 
             # compute indentation
@@ -2197,16 +2202,21 @@ def dump(obj, dest, **kwargs):
 
     try:
         dest.write(content + "\n")
-    except AttributeError:
+    except (AttributeError, TypeError) as e:
         # Avoid nested try-except blocks, since they lead to chained exceptions
         # (e.g. if the file isn’t found, etc.) that unnecessarily complicate the
         # stack trace.
-        pass
+        exception = e
     else:
         return
 
-    with open(dest, "w", encoding="utf-8") as f:
-        f.write(content + "\n")
+    if isinstance(exception, TypeError):
+        # file may be binary, encode in utf8 and try again
+        dest.write((content + "\n").encode('utf8'))
+    else:
+        # dest is a file name rather than a file pointer
+        with open(dest, "w", encoding="utf-8") as f:
+            f.write(content + "\n")
 
 
 # NestedText Utilities {{{1

tests/test_nestedtext.py

@@ -11,6 +11,7 @@
 from quantiphy import Quantity
 import subprocess
 import json
+import os
 
 test_api = Path(__file__).parent / 'official_tests' / 'api'
 import sys; sys.path.append(str(test_api))
@@ -1232,6 +1233,10 @@ def normalize_key(key, parent_keys):
         except TypeError:
             assert value == expected_value
 
+        with pytest.raises(KeyError) as exception:
+            value = nt.get_value("", normalized_keys)
+        assert exception.value.args == (normalized_keys[0],)
+
         # print(value)
         # try:
         #     assert index == int(value)
@@ -2027,8 +2032,8 @@ def test_dump_dialect():
         list:
     """, strip_nl="b")
 
-# Test round-trip {{{1
-# test_file_descriptors {{{2
+# Misc tests {{{1
+# test_file_descriptors() {{{2
 def test_file_descriptors(tmp_path):
     # program that writes out a simple NT document to stdout
     write_data = dedent("""
@@ -2052,14 +2057,29 @@ def test_file_descriptors(tmp_path):
         f"python {writer!s} | python {reader!s}",
         shell = True,
         capture_output = True,
-        env = {"COVERAGE_PROCESS_START":""},
+        env = {"COVERAGE_PROCESS_START":"", "PATH": os.environ["PATH"]}
     )
-    assert results.stdout == b""
-    assert results.stderr == b""
+    assert results.stdout.decode('utf8') == ""
+    assert results.stderr.decode('utf8') == ""
     assert results.returncode == 0
 
-# test_andyde {{{2
-def test_andyde(tmp_path):
+# test_binary_files() {{{2
+def test_binary_round_trip(tmp_path):
+    orig_data = {"dict": {}, "list": [], "str": "", "mls":"\\n"}
+    nt_path = tmp_path / "test.nt"
+
+    # dump nestedtext to a binary file
+    with nt_path.open('wb') as f:
+        test_nt = nt.dump(orig_data, f)
+
+    # read nestedtext from a binary file
+    with nt_path.open('rb') as f:
+        data_as_read = nt.load(f)
+
+    assert data_as_read == orig_data
+
+# test_round_trip() {{{2
+def test_round_trip(tmp_path):
     data_python = {
         "http://www.kde.org/standards/kcfg/1.0}kcfgfile": None,
         "http://www.kde.org/standards/kcfg/1.0}group": {