Do CLI import in __main__, not __init__

Importing the CLI code doubles the import time for httpx altogether. By
importing in httpx/__main__.py instead of in httpx/__init__.py, the
additional time only happens when running the httpx CLI, and not on
every "import httpx".

Author: natehardison

httpx/__init__.py

@@ -11,21 +11,6 @@
 from ._types import *
 from ._urls import *
 
-try:
-    from ._main import main
-except ImportError:  # pragma: no cover
-
-    def main() -> None:  # type: ignore
-        import sys
-
-        print(
-            "The httpx command line client could not run because the required "
-            "dependencies were not installed.\nMake sure you've installed "
-            "everything with: pip install 'httpx[cli]'"
-        )
-        sys.exit(1)
-
-
 __all__ = [
     "__description__",
     "__title__",
@@ -59,7 +44,6 @@ def main() -> None:  # type: ignore
     "InvalidURL",
     "Limits",
     "LocalProtocolError",
-    "main",
     "MockTransport",
     "NetRCAuth",
     "NetworkError",

httpx/__main__.py

@@ -0,0 +1,20 @@
+try:
+    from ._main import main
+except ImportError:  # pragma: no cover
+
+    def main() -> None:  # type: ignore
+        import sys
+
+        print(
+            "The httpx command line client could not run because the required "
+            "dependencies were not installed.\nMake sure you've installed "
+            "everything with: pip install 'httpx[cli]'"
+        )
+        sys.exit(1)
+
+
+__all__ = ["main"]
+
+
+if __name__ == "__main__":  # pragma: no cover
+    main()

pyproject.toml

@@ -57,7 +57,7 @@ zstd = [
 ]
 
 [project.scripts]
-httpx = "httpx:main"
+httpx = "httpx.__main__:main"
 
 [project.urls]
 Changelog = "https://github.com/encode/httpx/blob/master/CHANGELOG.md"

tests/test_main.py

@@ -3,7 +3,7 @@
 
 from click.testing import CliRunner
 
-import httpx
+import httpx.__main__
 
 
 def splitlines(output: str) -> typing.Iterable[str]:
@@ -16,15 +16,15 @@ def remove_date_header(lines: typing.Iterable[str]) -> typing.Iterable[str]:
 
 def test_help():
     runner = CliRunner()
-    result = runner.invoke(httpx.main, ["--help"])
+    result = runner.invoke(httpx.__main__.main, ["--help"])
     assert result.exit_code == 0
     assert "A next generation HTTP client." in result.output
 
 
 def test_get(server):
     url = str(server.url)
     runner = CliRunner()
-    result = runner.invoke(httpx.main, [url])
+    result = runner.invoke(httpx.__main__.main, [url])
     assert result.exit_code == 0
     assert remove_date_header(splitlines(result.output)) == [
         "HTTP/1.1 200 OK",
@@ -39,7 +39,7 @@ def test_get(server):
 def test_json(server):
     url = str(server.url.copy_with(path="/json"))
     runner = CliRunner()
-    result = runner.invoke(httpx.main, [url])
+    result = runner.invoke(httpx.__main__.main, [url])
     assert result.exit_code == 0
     assert remove_date_header(splitlines(result.output)) == [
         "HTTP/1.1 200 OK",
@@ -57,7 +57,7 @@ def test_binary(server):
     url = str(server.url.copy_with(path="/echo_binary"))
     runner = CliRunner()
     content = "Hello, world!"
-    result = runner.invoke(httpx.main, [url, "-c", content])
+    result = runner.invoke(httpx.__main__.main, [url, "-c", content])
     assert result.exit_code == 0
     assert remove_date_header(splitlines(result.output)) == [
         "HTTP/1.1 200 OK",
@@ -72,7 +72,7 @@ def test_binary(server):
 def test_redirects(server):
     url = str(server.url.copy_with(path="/redirect_301"))
     runner = CliRunner()
-    result = runner.invoke(httpx.main, [url])
+    result = runner.invoke(httpx.__main__.main, [url])
     assert result.exit_code == 1
     assert remove_date_header(splitlines(result.output)) == [
         "HTTP/1.1 301 Moved Permanently",
@@ -86,7 +86,7 @@ def test_redirects(server):
 def test_follow_redirects(server):
     url = str(server.url.copy_with(path="/redirect_301"))
     runner = CliRunner()
-    result = runner.invoke(httpx.main, [url, "--follow-redirects"])
+    result = runner.invoke(httpx.__main__.main, [url, "--follow-redirects"])
     assert result.exit_code == 0
     assert remove_date_header(splitlines(result.output)) == [
         "HTTP/1.1 301 Moved Permanently",
@@ -106,7 +106,9 @@ def test_follow_redirects(server):
 def test_post(server):
     url = str(server.url.copy_with(path="/echo_body"))
     runner = CliRunner()
-    result = runner.invoke(httpx.main, [url, "-m", "POST", "-j", '{"hello": "world"}'])
+    result = runner.invoke(
+        httpx.__main__.main, [url, "-m", "POST", "-j", '{"hello": "world"}']
+    )
     assert result.exit_code == 0
     assert remove_date_header(splitlines(result.output)) == [
         "HTTP/1.1 200 OK",
@@ -121,7 +123,7 @@ def test_post(server):
 def test_verbose(server):
     url = str(server.url)
     runner = CliRunner()
-    result = runner.invoke(httpx.main, [url, "-v"])
+    result = runner.invoke(httpx.__main__.main, [url, "-v"])
     assert result.exit_code == 0
     assert remove_date_header(splitlines(result.output)) == [
         "* Connecting to '127.0.0.1'",
@@ -145,7 +147,9 @@ def test_verbose(server):
 def test_auth(server):
     url = str(server.url)
     runner = CliRunner()
-    result = runner.invoke(httpx.main, [url, "-v", "--auth", "username", "password"])
+    result = runner.invoke(
+        httpx.__main__.main, [url, "-v", "--auth", "username", "password"]
+    )
     print(result.output)
     assert result.exit_code == 0
     assert remove_date_header(splitlines(result.output)) == [
@@ -172,15 +176,15 @@ def test_download(server):
     url = str(server.url)
     runner = CliRunner()
     with runner.isolated_filesystem():
-        runner.invoke(httpx.main, [url, "--download", "index.txt"])
+        runner.invoke(httpx.__main__.main, [url, "--download", "index.txt"])
         assert os.path.exists("index.txt")
         with open("index.txt", "r") as input_file:
             assert input_file.read() == "Hello, world!"
 
 
 def test_errors():
     runner = CliRunner()
-    result = runner.invoke(httpx.main, ["invalid://example.org"])
+    result = runner.invoke(httpx.__main__.main, ["invalid://example.org"])
     assert result.exit_code == 1
     assert splitlines(result.output) == [
         "UnsupportedProtocol: Request URL has an unsupported protocol 'invalid://'.",