Convert over to use attr

Make the class a bit easier to use, with built-in generated methods from
attr

cli.py

@@ -39,7 +39,7 @@ def build(files, lib):
 
         with open(f"{name}.yaml", "w") as template:
             click.echo(f'{head} Saving to "{name}.yaml"')
-            template.write(ct.yaml)
+            template.write(ct.yaml())
 
 
 cli.add_command(build)

policytool/models.py

@@ -1,5 +1,6 @@
 from typing import List
 
+import attr
 import yaml
 
 
@@ -9,15 +10,27 @@ def str_presenter(dumper, data):
     return dumper.represent_scalar("tag:yaml.org,2002:str", data)
 
 
+@attr.s(auto_attribs=True)
 class ConstraintTemplate(object):
-    def __init__(self, kind: str, rego: str, libs: List[str] = []):
-        self.name = kind.lower()
-        self.kind = kind
-        self.list_kind = f"{kind}List"
-        self.plural = self.name
-        self.singular = self.name.rstrip("s")
-        self.rego = rego
-        self.libs = libs
+    kind: str
+    rego: str
+    libs: List[str] = attr.Factory(list)
+
+    @property
+    def name(self):
+        return self.kind.lower()
+
+    @property
+    def plural(self):
+        return self.name
+
+    @property
+    def singular(self):
+        return self.name.rstrip("s")
+
+    @property
+    def list_kind(self):
+        return f"{self.kind}List"
 
     @property
     def _template(self):
@@ -45,7 +58,6 @@ def _template(self):
             temp["spec"]["targets"][0]["libs"] = self.libs
         return temp
 
-    @property
     def yaml(self):
         yaml.add_representer(str, str_presenter)
         return yaml.dump(self._template)

policytool/test_models.py

@@ -44,7 +44,7 @@ def test_default_libs(self, template):
 
     def test_yaml(self, template):
         assert (
-            template.yaml
+            template.yaml()
             == """apiVersion: templates.gatekeeper.sh/v1beta1
 kind: ConstraintTemplate
 metadata:

pyproject.toml

@@ -5,13 +5,14 @@ license = "Apache-2.0"
 description = "A set of utilities and classes for working with Open Policy Agent based tools, including Gatekeeper and Conftest"
 authors = ["Gareth Rushgrove <gareth@morethanseven.net>"]
 readme = "README.md"
-repository = "https://github.com/garethr/policytool
+repository = "https://github.com/garethr/policytool"
 
 [tool.poetry.dependencies]
 python = "^3.7"
 PyYAML = "^5.1"
 click = "^7.0"
 colorama = "^0.4.1"
+attr = "^0.3.1"
 
 [tool.poetry.scripts]
 policytool = "cli:cli"