Avoid ResourceWarning: unclosed file (#395)

A number of such warnings showed up when running e.g.
PYTHONWARNINGS=always python build_examples.py
PYTHONWARNINGS=always wireviz ../../examples/demo0?.yml
See #309 (comment)

Fix: All open() calls should be in a "with open() as x" statement
to ensure closing the file when exiting the block in any way.
Otherwise, use the new file_read_text() or file_write_text() functions
to read or write the whole utf-8 text file and closing it.

Co-authored-by: kvid <kvid@users.noreply.github.com>

Author: 17o2

src/wireviz/wireviz.py

@@ -16,9 +16,9 @@
 from wireviz.wv_harness import Harness
 from wireviz.wv_utils import (
     expand,
+    file_read_text,
     get_single_key_and_value,
     is_arrow,
-    open_file_read,
     smart_file_resolve,
 )
 
@@ -419,7 +419,7 @@ def _get_yaml_data_and_path(inp: Union[str, Path, Dict]) -> Tuple[Dict, Path]:
         try:
             yaml_path = Path(inp).expanduser().resolve(strict=True)
             # if no FileNotFoundError exception happens, get file contents
-            yaml_str = open_file_read(yaml_path).read()
+            yaml_str = file_read_text(yaml_path)
         except (FileNotFoundError, OSError, ValueError) as e:
             # if inp is a long YAML string, Pathlib will normally raise
             # FileNotFoundError or OSError(errno = ENAMETOOLONG) when

src/wireviz/wv_cli.py

@@ -11,7 +11,7 @@
 
 import wireviz.wireviz as wv
 from wireviz import APP_NAME, __version__
-from wireviz.wv_utils import open_file_read
+from wireviz.wv_utils import file_read_text
 
 format_codes = {
     # "c": "csv",  # TODO: support CSV
@@ -119,7 +119,7 @@ def wireviz(file, format, prepend, output_dir, output_name, version):
                 raise Exception(f"Path is not a file:\n{prepend_file}")
             print("Prepend file:", prepend_file)
 
-            prepend_input += open_file_read(prepend_file).read() + "\n"
+            prepend_input += file_read_text(prepend_file) + "\n"
     else:
         prepend_input = ""
 
@@ -140,7 +140,7 @@ def wireviz(file, format, prepend, output_dir, output_name, version):
             "Output file: ", f"{Path(_output_dir / _output_name)}.{output_formats_str}"
         )
 
-        yaml_input = open_file_read(file).read()
+        yaml_input = file_read_text(file)
         file_dir = file.parent
 
         yaml_input = prepend_input + yaml_input

src/wireviz/wv_harness.py

@@ -40,7 +40,7 @@
     embed_svg_images_file,
     generate_html_output,
 )
-from wireviz.wv_utils import OLD_CONNECTOR_ATTR, bom2tsv, check_old, open_file_write
+from wireviz.wv_utils import OLD_CONNECTOR_ATTR, bom2tsv, check_old, file_write_text
 
 
 @dataclass
@@ -424,7 +424,8 @@ def output(
         # bomlist = [[]]
         if "tsv" in fmt:
             tsv = bom2tsv(bomlist)
-            open_file_write(f"{filename}.tsv").write(tsv)
+            file_write_text(f"{filename}.bom.tsv", tsv)
+
         if "csv" in fmt:
             # TODO: implement CSV output (preferrably using CSV library)
             print("CSV output is not yet supported")

src/wireviz/wv_output.py

@@ -9,9 +9,9 @@
 from wireviz import APP_NAME, APP_URL, __version__
 from wireviz.wv_dataclasses import Metadata, Options
 from wireviz.wv_utils import (
+    file_read_text,
+    file_write_text,
     html_line_breaks,
-    open_file_read,
-    open_file_write,
     smart_file_resolve,
 )
 
@@ -95,14 +95,14 @@ def generate_html_output(
         # fall back to built-in simple template if no template was provided
         templatefile = Path(wireviz.__file__).parent / "templates/simple.html"
 
-    html = open_file_read(templatefile).read()
+    html = file_read_text(templatefile)
 
     # embed SVG diagram (only if used)
     def svgdata() -> str:
         return re.sub(
             "^<[?]xml [^?>]*[?]>[^<]*<!DOCTYPE [^>]*>",
             "<!-- XML and DOCTYPE declarations from SVG file removed -->",
-            open_file_read(f"{filename}.tmp.svg").read(),
+            file_read_text(f"{filename}.tmp.svg"),
             1,
         )
 
@@ -186,4 +186,4 @@ def replacement_if_used(key: str, func: Callable[[], str]) -> None:
     pattern = re.compile("|".join(replacements_escaped))
     html = pattern.sub(lambda match: replacements[match.group(0)], html)
 
-    open_file_write(f"{filename}.html").write(html)
+    file_write_text(f"{filename}.html", html)

src/wireviz/wv_utils.py

@@ -151,18 +151,31 @@ def clean_whitespace(inp):
 
 
 def open_file_read(filename):
+    """Open utf-8 encoded text file for reading - remember closing it when finished"""
     # TODO: Intelligently determine encoding
     return open(filename, "r", encoding="UTF-8")
 
 
 def open_file_write(filename):
+    """Open utf-8 encoded text file for writing - remember closing it when finished"""
     return open(filename, "w", encoding="UTF-8")
 
 
 def open_file_append(filename):
+    """Open utf-8 encoded text file for appending - remember closing it when finished"""
     return open(filename, "a", encoding="UTF-8")
 
 
+def file_read_text(filename: str) -> str:
+    """Read utf-8 encoded text file, close it, and return the text"""
+    return Path(filename).read_text(encoding="utf-8")
+
+
+def file_write_text(filename: str, text: str) -> int:
+    """Write utf-8 encoded text file, close it, and return the number of characters written"""
+    return Path(filename).write_text(text, encoding="utf-8")
+
+
 def is_arrow(inp):
     """
     Matches strings of one or multiple `-` or `=` (but not mixed)