jymchng · December 16, 2024 07:05 · Dec 16, 2024 · Dec 16, 2024 · Dec 16, 2024 · Dec 16, 2024
diff --git a/readme.md b/readme.md
@@ -2,4 +2,4 @@
 
 In the file, `env_variant.py`, the plan is to have `RollYourOwnNewTypeEnum` with variants that are only in this allowed set (`__VALID_MEMBERS__ = ["LOCAL", "DEV", "SIT", "UAT", "PREPROD", "PROD"]`).
 
-However, there seems to be no way to read `ENVVariant.my_replace(..)`?
+However, there seems to be no way to write `ENVVariant.my_replace(..)`?
diff --git a/requirements.txt b/requirements.txt
@@ -0,0 +1 @@
+pytest
diff --git a/readme.md b/readme.md
@@ -0,0 +1,5 @@
+# Challenge
+
+In the file, `env_variant.py`, the plan is to have `RollYourOwnNewTypeEnum` with variants that are only in this allowed set (`__VALID_MEMBERS__ = ["LOCAL", "DEV", "SIT", "UAT", "PREPROD", "PROD"]`).
+
+However, there seems to be no way to read `ENVVariant.my_replace(..)`?
diff --git a/env_variant.py b/env_variant.py
@@ -0,0 +1,68 @@
+import pytest
+from enum import Enum
+
+class ENVVariant(str):
+
+    __VALID_MEMBERS__ = ["LOCAL", "DEV", "SIT", "UAT", "PREPROD", "PROD"]
+
+    def __new__(cls, value: str):
+        members = ENVVariant.__VALID_MEMBERS__
+        if isinstance(value, RollYourOwnNewTypeEnum):
+            value_as_str = str(value.value)
+        else:
+            value_as_str = str(value)
+        if value_as_str not in members:
+            raise ValueError(f"`value` = {value} must be one of `{members}`; `value_as_str` = {value_as_str}")
+        return super().__new__(cls, value_as_str)
+
+    # why not i write my own `.replace(..)`
+    # yes, you can but how?
+    def my_replace(self, old: "ENVVariant", new: "ENVVariant", count: int=-1):
+        return ENVVariant(str(self).replace(str(old), str(new), count))
+
+class RollYourOwnNewTypeEnum(ENVVariant, Enum):
+
+    LOCAL = "LOCAL"
+    DEV = "DEV"
+    SIT = "SIT"
+    UAT = "UAT"
+    PREPROD = "PREPROD"
+    PROD = "PROD"
+
+def test_ryont_env_replace():
+
+    env = RollYourOwnNewTypeEnum.LOCAL
+
+    # expected outcomes
+    assert env is RollYourOwnNewTypeEnum.LOCAL # pass
+    assert env is not RollYourOwnNewTypeEnum.DEV # pass
+    assert isinstance(env, RollYourOwnNewTypeEnum) # pass
+
+    # now we try to replace
+    env = env.replace(RollYourOwnNewTypeEnum.LOCAL, RollYourOwnNewTypeEnum.DEV)
+
+    # we are hoping that it will continue to be a `RollYourOwnNewTypeEnum.DEV` but it is not
+    assert env is not RollYourOwnNewTypeEnum.DEV # pass, no longer a `RollYourOwnNewTypeEnum`
+    assert env is not RollYourOwnNewTypeEnum.LOCAL # pass, no longer a `RollYourOwnNewTypeEnum`
+    assert not isinstance(env, RollYourOwnNewTypeEnum)
+    assert isinstance(env, str) # 'downcast' (?) to `str`
+
+    with pytest.raises(AssertionError):
+        assert env is RollYourOwnNewTypeEnum.DEV
+
+    with pytest.raises(AssertionError):
+        assert env is RollYourOwnNewTypeEnum.DEV
+
+    with pytest.raises(AssertionError):
+        assert isinstance(env, RollYourOwnNewTypeEnum)
+
+    env = env.replace("DEV", "NotAnEnv")
+    assert env == "NotAnEnv" # this 'shouldn't' pass but it does
+
+    env = RollYourOwnNewTypeEnum.LOCAL
+
+    env = env.my_replace(RollYourOwnNewTypeEnum.LOCAL, RollYourOwnNewTypeEnum.PREPROD)
+
+    assert isinstance(env, str)
+    assert env is RollYourOwnNewTypeEnum.PREPROD
+    assert isinstance(env, RollYourOwnNewTypeEnum)
diff --git a/newtype_enum.py b/newtype_enum.py
@@ -0,0 +1,134 @@
+from newtype import NewType, newtype_exclude
+from enum import Enum
+import pytest
+
+class ENV(NewType(str), Enum):
+
+    LOCAL = "LOCAL"
+    DEV = "DEV"
+    SIT = "SIT"
+    UAT = "UAT"
+    PREPROD = "PREPROD"
+    PROD = "PROD"
+
+class RegularENV(str, Enum):
+
+    LOCAL = "LOCAL"
+    DEV = "DEV"
+    SIT = "SIT"
+    UAT = "UAT"
+    PREPROD = "PREPROD"
+    PROD = "PROD"
+
+class ENVVariant(str):
+
+    __VALID_MEMBERS__ = ["LOCAL", "DEV", "SIT", "UAT", "PREPROD", "PROD"]
+
+    def __new__(cls, value: str):
+        members = ENVVariant.__VALID_MEMBERS__
+        if isinstance(value, RollYourOwnNewTypeEnum):
+            value_as_str = str(value.value)
+        else:
+            value_as_str = str(value)
+        if value_as_str not in members:
+            raise ValueError(f"`value` = {value} must be one of `{members}`; `value_as_str` = {value_as_str}")
+        return super().__new__(cls, value_as_str)
+
+    # why not i write my own `.replace(..)`
+    # yes, you can but how?
+    def my_replace(self, old: "ENVVariant", new: "ENVVariant", count: int=-1):
+        return ENVVariant(str(self).replace(str(old), str(new), count))
+
+class RollYourOwnNewTypeEnum(ENVVariant, Enum):
+
+    LOCAL = "LOCAL"
+    DEV = "DEV"
+    SIT = "SIT"
+    UAT = "UAT"
+    PREPROD = "PREPROD"
+    PROD = "PROD"
+
+
+def test_nt_env_replace():
+
+    env = ENV.LOCAL
+
+    assert env is ENV.LOCAL
+    assert env is not ENV.DEV
+    assert isinstance(env, ENV)
+
+    # let's say now we want to replace the environment
+    # nevermind about the reason why we want to do so
+    env = env.replace(ENV.LOCAL, ENV.DEV)
+
+    # replacement is successful
+    assert env is ENV.DEV
+    assert env is not ENV.LOCAL
+
+    # still an `ENV`
+    assert isinstance(env, ENV)
+    assert isinstance(env, str)
+
+    with pytest.raises(ValueError):
+        # cannot replace with something that is not a `ENV`
+        env = env.replace(ENV.DEV, "NotAnEnv")
+
+    with pytest.raises(ValueError):
+        # cannot even make 'DEV' -> 'dev'
+        env = env.lower()
+
+def test_reg_env_replace():
+
+    env = RegularENV.LOCAL
+
+    # expected outcomes
+    assert env is RegularENV.LOCAL # pass
+    assert env is not RegularENV.DEV # pass
+    assert isinstance(env, RegularENV) # pass
+
+    # now we try to replace
+    env = env.replace(RegularENV.LOCAL, RegularENV.DEV)
+
+    # we are hoping that it will continue to be a `RegularENV.DEV` but it is not
+    assert env is not RegularENV.DEV # pass, no longer a `RegularENV`
+    assert env is not RegularENV.LOCAL # pass, no longer a `RegularENV`
+    assert not isinstance(env, RegularENV)
+    assert isinstance(env, str) # 'downcast' (?) to `str`
+
+def test_ryont_env_replace():
+
+    env = RollYourOwnNewTypeEnum.LOCAL
+
+    # expected outcomes
+    assert env is RollYourOwnNewTypeEnum.LOCAL # pass
+    assert env is not RollYourOwnNewTypeEnum.DEV # pass
+    assert isinstance(env, RollYourOwnNewTypeEnum) # pass
+
+    # now we try to replace
+    env = env.replace(RollYourOwnNewTypeEnum.LOCAL, RollYourOwnNewTypeEnum.DEV)
+
+    # we are hoping that it will continue to be a `RollYourOwnNewTypeEnum.DEV` but it is not
+    assert env is not RollYourOwnNewTypeEnum.DEV # pass, no longer a `RollYourOwnNewTypeEnum`
+    assert env is not RollYourOwnNewTypeEnum.LOCAL # pass, no longer a `RollYourOwnNewTypeEnum`
+    assert not isinstance(env, RollYourOwnNewTypeEnum)
+    assert isinstance(env, str) # 'downcast' (?) to `str`
+
+    with pytest.raises(AssertionError):
+        assert env is RollYourOwnNewTypeEnum.DEV
+
+    with pytest.raises(AssertionError):
+        assert env is RollYourOwnNewTypeEnum.DEV
+
+    with pytest.raises(AssertionError):
+        assert isinstance(env, RollYourOwnNewTypeEnum)
+
+    env = env.replace("DEV", "NotAnEnv")
+    assert env == "NotAnEnv" # this 'shouldn't' pass but it does
+
+    env = RollYourOwnNewTypeEnum.LOCAL
+
+    env = env.my_replace(RollYourOwnNewTypeEnum.LOCAL, RollYourOwnNewTypeEnum.PREPROD)
+
+    assert isinstance(env, str)
+    assert env is RollYourOwnNewTypeEnum.PREPROD
+    assert isinstance(env, RollYourOwnNewTypeEnum)