Add '--hook' option (#2)

.devcontainer/post_create.sh

@@ -28,4 +28,3 @@ if [ ! -f "$SRC_CONDA_SPAWN/pyproject.toml" ]; then
     echo "https://github.com/conda-incubator/conda-spawn not found! Please clone or mount to $SRC_CONDA_SPAWN"
     exit 1
 fi
-

.github/workflows/test.yml

@@ -51,7 +51,7 @@ jobs:
           pixi run --environment ${{ env.PIXI_ENV_NAME }} conda info
       - name: Run tests
         run: pixi run --environment ${{ env.PIXI_ENV_NAME }} test --basetemp=${{ runner.os == 'Windows' && 'D:\\temp' || runner.temp }}
-  
+
   build-conda:
     name: Build conda package (${{ matrix.os }})
     runs-on: ${{ matrix.os }}
@@ -73,4 +73,3 @@ jobs:
           pixi run --environment build dev
       - name: Build recipe
         run: pixi run --environment build build
-

README.md

@@ -52,13 +52,13 @@ For in-script usage, please consider these replacements for `conda activate`:
 For Unix shell scripts:
 
 ```bash
-eval "$(conda shell.posix activate <ENV-NAME>)"
+eval "$(conda spawn --hook --shell posix -n <ENV-NAME>)"
 ```
 
 For Windows CMD scripts:
 
 ```cmd
-FOR /F "tokens=*" %%g IN ('conda shell.cmd.exe activate <ENV-NAME>') do @CALL %%g
+FOR /F "tokens=*" %%g IN ('conda spawn --hook --shell cmd -n <ENV-NAME>') do @CALL %%g
 ```
 
 For Windows Powershell scripts:
@@ -72,7 +72,7 @@ For example, if you want to create a new environment and activate it, it would l
 ```bash
 # Assumes `conda` is in PATH
 conda create -n new-env python numpy
-eval "$(conda shell.posix activate new-env)"
+eval "$(conda spawn --hook --shell powershell -n new-env)"
 python -c "import numpy"
 ```
 

conda_spawn/__init__.py

@@ -1,4 +1,5 @@
 """
 conda go: activate conda environments in new shell processes.
 """
-from .main import spawn
+
+from .main import spawn, hook  # noqa

conda_spawn/cli.py

@@ -5,34 +5,69 @@
 from __future__ import annotations
 
 import argparse
+from textwrap import dedent
 
+from conda.exceptions import ArgumentError
 from conda.cli.conda_argparse import (
     add_parser_help,
     add_parser_prefix,
 )
 
 
 def configure_parser(parser: argparse.ArgumentParser):
+    from .shell import SHELLS
+
     add_parser_help(parser)
     add_parser_prefix(parser, prefix_required=True)
 
     parser.add_argument(
         "command",
+        metavar="COMMAND [args]",
         nargs="*",
-        help="Optional program and arguments to run after starting the shell.",
+        help="Optional program to run after starting the shell. "
+        "Use -- before the program if providing arguments.",
     )
     shell_group = parser.add_argument_group("Shell options")
     shell_group.add_argument(
-        "-s",
+        "--hook",
+        action="store_true",
+        help=(
+            "Print the shell activation logic so it can be sourced in-process. "
+            "This is meant to be used in scripts only."
+        ),
+    )
+    shell_group.add_argument(
         "--shell",
-        help="Shell to use for the new session. "
-        "If not specified, autodetect shell in use.",
+        choices=SHELLS,
+        help="Shell to use for the new session. If not specified, autodetect shell in use.",
     )
 
+    parser.prog = "conda spawn"
+    parser.epilog = dedent(
+        """
+        Examples for --hook usage in different shells:
+          POSIX:
+            source "$(conda spawn --hook -n ENV-NAME)"
+          CMD:
+            FOR /F "tokens=*" %%g IN ('conda spawn --hook -n ENV-NAME') do @CALL %%g
+          Powershell:
+            conda spawn --hook -n ENV-NAME | Out-String | Invoke-Expression
+        """
+    ).lstrip()
+
 
 def execute(args: argparse.Namespace) -> int:
-    from .main import spawn, environment_speficier_to_path, shell_specifier_to_shell
+    from .main import (
+        hook,
+        spawn,
+        environment_speficier_to_path,
+        shell_specifier_to_shell,
+    )
 
     prefix = environment_speficier_to_path(args.name, args.prefix)
     shell = shell_specifier_to_shell(args.shell)
+    if args.hook:
+        if args.command:
+            raise ArgumentError("COMMAND cannot be provided with --hook.")
+        return hook(prefix, shell)
     return spawn(prefix, shell, command=args.command)

conda_spawn/exceptions.py

@@ -1,5 +1,4 @@
-"""
-"""
+""" """
 
 from conda.base.constants import COMPATIBLE_SHELLS
 from conda.common.io import dashlist
@@ -14,4 +13,3 @@ def __init__(self, name: str):
             f"{dashlist(COMPATIBLE_SHELLS)}"
         )
         super().__init__(message)
-

conda_spawn/main.py

@@ -18,7 +18,17 @@ def spawn(
 ) -> int:
     if shell_cls is None:
         shell_cls = detect_shell_class()
-    return shell_cls().spawn(prefix, command=command)
+    return shell_cls(prefix).spawn(command=command)
+
+
+def hook(prefix: Path, shell_cls: Shell | None = None) -> int:
+    if shell_cls is None:
+        shell_cls = detect_shell_class()
+    script = shell_cls(prefix).script()
+    prompt = shell_cls(prefix).prompt()
+    print(script)
+    print(prompt)
+    return 0
 
 
 def environment_speficier_to_path(

conda_spawn/plugin.py

@@ -9,7 +9,7 @@
 def conda_subcommands():
     yield plugins.CondaSubcommand(
         name="spawn",
-        summary="activate conda environments in new shell processes",
+        summary="Activate conda environments in new shell processes.",
         action=cli.execute,
         configure_parser=cli.configure_parser,
     )