Simplify example to not use translate requirement (#85)

As explained in #84, we think it's valuable for this example repository to be simple. In particular, we are demoing Pants itself, not the underlying code. 

This simplifies the project to use our own hardcoded `translate.json`, rather than the much more robust `translate` requirement. We still demonstrate the same things `translate` was showing for us:

* third-party management
* loading resource files

There's an added benefit that the repository is now much faster to build, especially on Apple Silicon where `lxml` must be compiled from source. Likewise, I no longer have to force Pants to use Py39+ for this to build on my M1! The default of 3.7+ now works.

Author: Eric-Arellano

constraints.txt

@@ -1,19 +1,5 @@
-# Generated by build-support/generate_constraints.sh on Mon Aug  2 21:58:13 UTC 2021
+# Generated by build-support/generate_constraints.sh on Fri Nov 12 13:02:01 MST 2021
 ansicolors==1.1.8
-certifi==2021.5.30
-charset-normalizer==2.0.4
-click==8.0.1
-idna==3.2
-importlib-metadata==4.6.3
-libretranslatepy==2.1.1
-lxml==4.6.3
-pip==21.2.2
-requests==2.26.0
+pip==21.3.1
 setuptools==56.2.0
-six==1.16.0
-translate==3.6.1
-types-futures==0.1.6
-types-setuptools==57.0.0
-typing-extensions==3.10.0.0
-urllib3==1.26.6
-zipp==3.5.0
+types-setuptools==57.4.2

helloworld/BUILD

@@ -2,18 +2,8 @@
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
 # This target sets the metadata for all the Python non-test files in this directory.
-#
-# * `name` defaults to the name of this directory, i.e., `helloworld`.
-# * `sources` defaults to ['*.py', '!*_test.py', '!test_*.py', '!conftest.py'].
-# * Pants cannot infer dependencies on resources targets, so we explicitly add it.
 python_library(
-    dependencies=[":config_file"],
-)
-
-# This target teaches Pants about our JSON file, which allows for other targets to depend on it.
-resources(
-    name="config_file",
-    sources=["config.json"],
+    name="lib",
 )
 
 # This target allows us to bundle our app into a PEX binary file via

helloworld/config.json

@@ -3,13 +3,19 @@
 
 # This target sets the metadata for all the Python non-test files in this directory.
 #
-# * `name` defaults to the name of this directory, i.e., `greet`.
-# * `sources` defaults to ['*.py', '!*_test.py', '!test_*.py', '!conftest.py'].
-# * `dependencies` are inferred.
-python_library()
+# * Pants cannot infer dependencies on `resources` targets, so we explicitly add the dep.
+python_library(
+    name="lib",
+    dependencies=[":translations"],
+)
 
 # This target sets the metadata for all the Python test files in this directory.
-#
-# * `sources` defaults to ['*_test.py', 'test_*.py', 'conftest.py'].
-# * `dependencies` are inferred.
-python_tests(name='tests')
+python_tests(
+    name="tests",
+)
+
+# This target teaches Pants about our JSON file, which allows other targets to depend on it.
+resources(
+    name="translations",
+    sources=["translations.json"],
+)

helloworld/greet/BUILD

@@ -1,21 +1,30 @@
 # Copyright 2020 Pants project contributors.
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
+from __future__ import annotations
+
+import json
 import random
-from typing import List
 
-from helloworld.util.lang import LanguageTranslator
+import pkg_resources
 
+from helloworld.translator.translator import LanguageTranslator
 
-class Greeter:
-    def __init__(self, greetings: List[str], languages: List[str]) -> None:
-        self._greetings = greetings
-        self._language_translator = LanguageTranslator(languages=languages)
 
-    def translated_greeting(self) -> str:
-        random_greeting = random.choice(self._greetings)
-        return self._language_translator.translate_to_random_language(random_greeting)
+class Greeter:
+    def __init__(
+        self, *, translations: dict[str, dict[str, str]] | None = None
+    ) -> None:
+        self._translations = (
+            translations
+            if translations is not None
+            else json.loads(
+                pkg_resources.resource_string(__name__, "translations.json")
+            )
+        )
+        self._translator = LanguageTranslator(self._translations)
 
     def greet(self, name: str) -> str:
-        greeting = self.translated_greeting()
+        random_greeting = random.choice(list(self._translations.keys()))
+        greeting = self._translator.translate_to_random_language(random_greeting)
         return f"{greeting}, {name}!".capitalize()

helloworld/greet/greeting.py

@@ -5,5 +5,5 @@
 
 
 def test_greeter() -> None:
-    greeter = Greeter(languages=["es"], greetings=["good morning"])
-    assert greeter.greet("world") == "Buenos días, world!"
+    greeter = Greeter(translations={"hello": {"es": "hola"}})
+    assert greeter.greet("test") == "Hola, test!"

helloworld/greet/greeting_test.py

@@ -0,0 +1,18 @@
+{
+  "hello": {
+    "es": "hola",
+    "fr": "bonjour",
+    "af": "hallo",
+    "ch": "你好",
+    "ru": "Привет",
+    "cs": "ahoj"
+  },
+  "good night": {
+    "es": "buenas noches",
+    "fr": "bonne nuit",
+    "af": "Goeie nag",
+    "ch": "晚安",
+    "ru": "спокойной ночи",
+    "cs": "dobrou noc"
+  }
+}

helloworld/greet/translations.json

@@ -4,14 +4,11 @@
 from colors import green
 
 from helloworld.greet.greeting import Greeter
-from helloworld.util.config import Config
 
 
 def say_hello() -> None:
-    config = Config.load_from_json_resource(__name__, "config.json")
-    greeter = Greeter(languages=config.languages, greetings=config.greetings)
-    sentence = greeter.greet("world")
-    print(green(sentence))
+    greeting = Greeter().greet("Pantsbuild")
+    print(green(greeting))
 
 
 if __name__ == "__main__":

helloworld/main.py

@@ -2,36 +2,24 @@
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
 # This target sets the metadata for all the Python non-test files in this directory.
-#
-# * `name` defaults to the name of this directory, i.e., `util`.
-# * `sources` defaults to ['*.py', '!*_test.py', '!test_*.py', '!conftest.py'].
-# * `dependencies` are inferred.
-python_library()
+python_library(
+    name="lib",
+)
 
 # This target sets the metadata for all the Python test files in this directory.
-#
-# * `sources` defaults to ['*_test.py', 'test_*.py', 'conftest.py'].
-# * Pants cannot infer dependencies on `resources` targets, so we explicitly add the dep.
 python_tests(
-    name='tests',
-    dependencies=[":test_data"],
-)
-
-# This target teaches Pants about our JSON file, which allows for other targets to depend on it.
-resources(
-    name='test_data',
-    sources=['*_test_data.json'],
+    name="tests",
 )
 
 # This target allows us to build a `.whl` bdist and a `.tar.gz` sdist by auto-generating
 #  `setup.py`. See https://www.pantsbuild.org/docs/python-distributions.
 #
-# Because this target has no source code, Pants cannot infer dependencies. We depend on `:util`,
+# Because this target has no source code, Pants cannot infer dependencies. We depend on `:lib`,
 #  which means we'll include all the non-test Python files in this directory, and any of
 #  their dependencies.
 python_distribution(
     name="dist",
-    dependencies=[":util"],
+    dependencies=[":lib"],
     setup_py_commands=["bdist_wheel", "sdist"],
     provides=setup_py(
         name='helloworld.util',

helloworld/util/BUILD renamed to helloworld/translator/BUILD

@@ -0,0 +1,46 @@
+# Copyright 2020 Pants project contributors.
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+from __future__ import annotations
+
+import random
+from dataclasses import dataclass
+
+
+class UnknownLanguage(Exception):
+    pass
+
+
+class UnknownPhrase(Exception):
+    pass
+
+
+@dataclass
+class LanguageTranslator:
+    """A mapping of phrases (in English) to ISO 639 language codes (like `es`,
+    `fr`) and their translation.
+
+    Assumes that every phrase is translated into the same languages.
+    """
+
+    phrases_to_translations: dict[str, dict[str, str]]
+
+    @property
+    def all_languages(self) -> set[str]:
+        return {
+            lang
+            for translations in self.phrases_to_translations.values()
+            for lang in translations.keys()
+        }
+
+    def translate(self, lang: str, phrase: str) -> str:
+        if phrase not in self.phrases_to_translations:
+            raise UnknownPhrase(phrase)
+        translations = self.phrases_to_translations[phrase]
+        if lang not in translations:
+            raise UnknownLanguage(lang)
+        return translations[lang]
+
+    def translate_to_random_language(self, phrase: str) -> str:
+        lang = random.choice(sorted(self.all_languages))
+        return self.translate(lang, phrase)

helloworld/util/__init__.py renamed to helloworld/translator/__init__.py

@@ -0,0 +1,34 @@
+# Copyright 2020 Pants project contributors.
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+import pytest
+
+from helloworld.translator.translator import (
+    LanguageTranslator,
+    UnknownLanguage,
+    UnknownPhrase,
+)
+
+
+def test_language_translator() -> None:
+    translator = LanguageTranslator(
+        {
+            "hello": {"es": "hola", "ar": "مرحبًا"},
+            "computer": {"es": "computadora", "ar": "حاسوب"},
+        }
+    )
+    assert translator.translate("es", "hello") == "hola"
+    assert translator.translate("ar", "hello") == "مرحبًا"
+    assert translator.translate("es", "computer") == "computadora"
+
+
+def test_unknown_phrase() -> None:
+    translator = LanguageTranslator({"hello": {"es": "hola"}})
+    with pytest.raises(UnknownPhrase):
+        translator.translate("es", "good morning")
+
+
+def test_unknown_language() -> None:
+    translator = LanguageTranslator({"hello": {"es": "hola"}})
+    with pytest.raises(UnknownLanguage):
+        translator.translate("ch", "hello")

helloworld/translator/translator.py

@@ -27,8 +27,5 @@ error_summary = True
 [mypy-colors]
 ignore_missing_imports = True
 
-[mypy-translate]
-ignore_missing_imports = True
-
 [mypy-pytest]
 ignore_missing_imports = True