Replace the PerfData dataclass with a named tuple.

- Works on Python 3.6.
- The upsides of dataclass don't help in this case.
- Is faster and uses less memory (although in this case it would hard to
  even measure the difference).

.gitlab-ci.yml

@@ -20,7 +20,6 @@ build-executable:
   extends: .python3-build
   before_script:
     - poetry install --no-dev
-    - poetry run pip freeze
   script:
     - poetry run make
   artifacts:

Makefile

@@ -2,7 +2,7 @@
 all: dist/mnpw
 
 dist/mnpw: mnpw/*.py pyproject.toml *.rst LICENSE.txt
-	pyinstaller --noconfirm --onefile "--name=$$(basename $@)" --hidden-import dataclasses  mnpw/__init__.py
+	pyinstaller --noconfirm --onefile "--name=$$(basename $@)" mnpw/__init__.py
 
 .PHONY: clean
 clean:

mnpw/nagios.py

@@ -5,10 +5,10 @@ https://assets.nagios.com/downloads/nagioscore/docs/nagioscore/3/en/pluginapi.ht
 """
 # pylint: disable=logging-fstring-interpolation
 
+import collections
 import enum
 import logging
 import subprocess  # nosec
-from dataclasses import dataclass
 
 DEFAULT_TIMEOUT = 10  # In seconds.
 
@@ -22,67 +22,64 @@ class NagiosCode(enum.IntEnum):
     UNKNOWN = 3
 
 
-@dataclass()
-class PerfData:
-    """Performance data.
-
-    As published by a Nagios plugin.
-    """
+PerfData = collections.namedtuple(
+    "PerfData", ["name", "value", "unit", "warning", "critical", "min", "max"]
+)
+PerfData.__new__.__defaults__ = tuple([None] * 7)
 
-    name: str
-    value: float
-    unit: str = ""
-    warning: float = None
-    critical: float = None
-    min: float = None
-    max: float = None
 
-    def __init__(self, line):  # noqa: MC0001
-        """Initialize using a perf data string output from a plugin."""
+def parse_perf_data(line):  # noqa: MC0001
+    """Convert a single-line string to a DataPerf tuple."""
     if len(line.splitlines()) > 1:
         raise RuntimeError("Can only parse a single line at a time.")
+
     fields = line.split(";")
-        self.name, self.value = fields[0].split("=")
+    name, value = fields[0].split("=")
 
     # Clean the name, handle a quoted name.
-        self.name = self.name.strip()
-        if self.name[0] in ["'", '"']:
-            self.name = self.name[1:]
-        if self.name[-1] in ["'", '"']:
-            self.name = self.name[:-1]
-        self.name = self.name.strip()
+    name = name.strip()
+    if name[0] in ["'", '"']:
+        name = name[1:]
+    if name[-1] in ["'", '"']:
+        name = name[:-1]
+    name = name.strip()
+    pd = {"name": name}  # pylint: disable=invalid-name
 
     # Split the unit and value.
-        if not self.value[-1].isdigit():
-            for i in range(len(self.value) - 1, 0, -1):
-                if self.value[i].isdigit():
+    if not value[-1].isdigit():
+        for i in range(len(value) - 1, 0, -1):
+            if value[i].isdigit():
                 break
-            self.value, self.unit = (
-                float(self.value[: i + 1]),
-                self.value[i + 1 :],  # noqa: E203
+        value, unit = (
+            float(value[: i + 1]),
+            value[i + 1 :],  # noqa: E203
         )
+    pd["value"] = value
+    pd["unit"] = unit
 
     # Get the remaining fields, if available.
     try:
-            self.warning = float(fields[1])
+        pd["warning"] = float(fields[1])
     except Exception as ex:  # pylint: disable=broad-except
         logging.info(str(ex))
 
     try:
-            self.critical = float(fields[2])
+        pd["critical"] = float(fields[2])
     except Exception as ex:  # pylint: disable=broad-except
         logging.info(str(ex))
 
     try:
-            self.min = float(fields[3])
+        pd["min"] = float(fields[3])
     except Exception as ex:  # pylint: disable=broad-except
         logging.info(str(ex))
 
     try:
-            self.max = float(fields[4])
+        pd["max"] = float(fields[4])
     except Exception as ex:  # pylint: disable=broad-except
         logging.info(str(ex))
 
+    return PerfData(**pd)
+
 
 class Check:
     # pylint: disable=invalid-name
@@ -121,7 +118,7 @@ class Check:
         if "|" in lines[0]:
             p1, p2 = lines[0].split("|")
             self.Output = p1.strip()
-            self.PerfData.append(PerfData(p2))
+            self.PerfData.append(parse_perf_data(p2))
         else:
             self.Output = lines[0].strip()
 
@@ -131,12 +128,12 @@ class Check:
         processing_perfdata = False
         for line in lines[1:]:
             if processing_perfdata:
-                self.PerfData.append(PerfData(line))
+                self.PerfData.append(parse_perf_data(line))
             else:
                 if "|" in line:
                     self.AdditionalOutput.append(line.split("|")[0].strip())
                     processing_perfdata = True
-                    self.PerfData.append(PerfData(line.split("|")[1]))
+                    self.PerfData.append(parse_perf_data(line.split("|")[1]))
                 else:
                     self.AdditionalOutput.append(line)
 

pyproject.toml

@@ -28,7 +28,6 @@ exclude = [
 [tool.poetry.dependencies]
 python = "^3.6.1"
 requests = "^2.25.1"
-dataclasses = { version = '^0.8', python = '<3.7'}
 
 [tool.poetry.dev-dependencies]
 pre-commit = "^2.13.0"

tests/test_nagios.py

@@ -114,7 +114,7 @@ def test_output_parsing(output):
 @pytest.mark.parametrize("line", PERF_DATA)
 def test_data_perf(line):
     """Test parsing of perfdata."""
-    pd = nagios.PerfData(line)
+    pd = nagios.parse_perf_data(line)
     assert isinstance(pd.name, str)
     assert len(pd.name) > 0
     assert isinstance(pd.value, float)