08 · 环境、依赖和 import

# whereis.py —— import 失败时，把「解释器到底在哪找过」打出来
import importlib.util
import sys

for name in ("json", "yaml", "pyyaml", "pandas"):
    spec = importlib.util.find_spec(name)
    print(f"{name:8s} → {spec.origin if spec else '（没找到）'}")

print("\n它按这个顺序找（sys.path）：")
for i, p in enumerate(sys.path):
    print(f"  [{i}] {p or '（空串 = 当前目录）'}")

# modcache.py —— import 两次，模块体只跑一次
import os
import subprocess
import sys
import tempfile

d = tempfile.mkdtemp()
with open(os.path.join(d, "heavy.py"), "w", encoding="utf-8") as fh:
    fh.write("print('  [heavy.py 的模块体在跑]')\nX = 1\n")
with open(os.path.join(d, "main.py"), "w", encoding="utf-8") as fh:
    fh.write("import importlib, sys\n"
             "print('第一次 import：')\n"
             "import heavy\n"
             "print('第二次 import：')\n"
             "import heavy\n"
             "print('  heavy in sys.modules ->', 'heavy' in sys.modules)\n"
             "print('reload：')\n"
             "importlib.reload(heavy)\n")
r = subprocess.run([sys.executable, "main.py"], cwd=d,
                   capture_output=True, text=True, encoding="utf-8")
print((r.stdout + r.stderr).strip())

# shadow.py —— 自己写的 random.py 会顶掉标准库
import os
import subprocess
import sys
import tempfile

d = tempfile.mkdtemp()
with open(os.path.join(d, "random.py"), "w", encoding="utf-8") as fh:
    fh.write("MY_OWN = 1\n")                       # 我自己的小工具
with open(os.path.join(d, "main.py"), "w", encoding="utf-8") as fh:
    fh.write("import random\n"
             "print('random.__file__ =', random.__file__)\n"
             "print(random.randint(1, 6))\n")

r = subprocess.run([sys.executable, "main.py"], cwd=d,
                   capture_output=True, text=True, encoding="utf-8")
print((r.stdout + r.stderr).strip())
print("退出码 =", r.returncode)

# circular.py —— 循环 import 的报错长什么样，以及为什么换个写法就好了
import os
import subprocess
import sys
import tempfile

d = tempfile.mkdtemp()
files = {
    "models.py":  "from db import save\n\nclass User:\n    pass\n",
    "db.py":      "from models import User\n\ndef save(u):\n    return isinstance(u, User)\n",
    "main.py":    "import models\nprint('导入成功')\n",
    # ⭐ 换个写法：把 import 挪进函数体
    "models2.py": "from db2 import save\n\nclass User:\n    pass\n",
    "db2.py":     "def save(u):\n    from models2 import User\n    return isinstance(u, User)\n",
    "main2.py":   "import models2\nprint('导入成功')\n",
}
for name, body in files.items():
    with open(os.path.join(d, name), "w", encoding="utf-8") as fh:
        fh.write(body)

for entry in ("main.py", "main2.py"):
    r = subprocess.run([sys.executable, entry], cwd=d,
                       capture_output=True, text=True, encoding="utf-8")
    print(f"--- python {entry}")
    print((r.stdout + r.stderr).strip().replace(d, "<tmp>"))

# dashm.py —— python pkg/tool.py 和 python -m pkg.tool 不是一回事
import os
import subprocess
import sys
import tempfile

root = tempfile.mkdtemp()
pkg = os.path.join(root, "pkg")
os.makedirs(pkg)
open(os.path.join(pkg, "__init__.py"), "w").close()
with open(os.path.join(pkg, "conf.py"), "w", encoding="utf-8") as fh:
    fh.write("NAME = 'prod'\n")
with open(os.path.join(pkg, "tool.py"), "w", encoding="utf-8") as fh:
    fh.write("import sys\n"
             "print('  sys.path[0] =', sys.path[0])\n"
             "from pkg.conf import NAME\n"          # ⭐ 就是这一行的成败不同
             "print('  NAME =', NAME)\n")

for argv in (["pkg/tool.py"], ["-m", "pkg.tool"]):
    r = subprocess.run([sys.executable, *argv], cwd=root,
                       capture_output=True, text=True, encoding="utf-8")
    print(f"--- python {' '.join(argv)}   (cwd = 项目根)")
    print((r.stdout + r.stderr).strip().replace(root, "<root>"))

# venv_probe.py —— venv 到底改了什么：建一个，然后拿它和外面的解释器对比
import os
import subprocess
import sys
import tempfile
import venv

root = tempfile.mkdtemp()
env_dir = os.path.join(root, ".venv")
venv.EnvBuilder(with_pip=False).create(env_dir)          # ⭐ 不装 pip，快很多

py = os.path.join(env_dir, "Scripts", "python.exe")      # Windows
if not os.path.exists(py):
    py = os.path.join(env_dir, "bin", "python")          # Linux / macOS

CODE = ("import sys, site;"
        "print('  sys.prefix      =', sys.prefix);"
        "print('  sys.base_prefix =', sys.base_prefix);"
        "print('  site-packages   =', site.getsitepackages()[-1])")

for label, exe in (("外面的解释器", sys.executable), ("venv 里的解释器", py)):
    r = subprocess.run([exe, "-c", CODE], capture_output=True, text=True,
                       encoding="utf-8")
    print(label)
    print(r.stdout.rstrip().replace(root, "<tmp>"))

print("\n.venv/pyvenv.cfg 的内容：")
with open(os.path.join(env_dir, "pyvenv.cfg"), encoding="utf-8") as fh:
    print(fh.read().strip())

# in_venv.py —— 两行判断当前解释器属于哪个环境
import sys

print("解释器：", sys.executable)
print("在 venv 里吗：", sys.prefix != sys.base_prefix)

# deps.py —— 你写了 1 行 requirements，实际装进来几个包
import importlib.metadata as md


def closure(name, seen=None):
    seen = seen if seen is not None else set()
    key = name.lower().replace("_", "-")
    if key in seen:
        return seen
    seen.add(key)
    try:
        reqs = md.requires(key) or []
    except md.PackageNotFoundError:
        return seen
    for r in reqs:
        if ";" in r and "extra ==" in r:          # ⭐ 可选依赖，默认不装
            continue
        dep = r.split(";")[0].split("[")[0].strip()
        for sep in ("==", ">=", "<=", "~=", "!=", ">", "<", " ", "("):
            dep = dep.split(sep)[0]
        if dep:
            closure(dep, seen)
    return seen


for top in ("requests", "torch"):
    got = closure(top)
    print(f"requirements.txt 只写了 `{top}` →  实际拉进来 {len(got)} 个包")
    print("   ", ", ".join(sorted(got)))

# editable.py —— pip install -e . 装进去的到底是什么
import os
import subprocess
import sys
import tempfile
import venv

root = tempfile.mkdtemp()
src = os.path.join(root, "proj", "mypkg")
os.makedirs(src)
with open(os.path.join(src, "__init__.py"), "w", encoding="utf-8") as fh:
    fh.write("VERSION = 'v1'\n")
with open(os.path.join(root, "proj", "pyproject.toml"), "w", encoding="utf-8") as fh:
    fh.write('[project]\nname = "mypkg"\nversion = "0.1.0"\n'
             '[build-system]\nrequires = ["setuptools"]\n'
             'build-backend = "setuptools.build_meta"\n')

env_dir = os.path.join(root, ".venv")
venv.EnvBuilder(with_pip=True).create(env_dir)
py = os.path.join(env_dir, "Scripts", "python.exe")
if not os.path.exists(py):
    py = os.path.join(env_dir, "bin", "python")

subprocess.run([py, "-m", "pip", "install", "-q", "-e", "."],
               cwd=os.path.join(root, "proj"), capture_output=True, text=True)

r = subprocess.run([py, "-c", "import mypkg; print(mypkg.__file__); print(mypkg.VERSION)"],
                   capture_output=True, text=True, encoding="utf-8")
print("装完之后 import 到的是：")
print(" ", r.stdout.strip().replace(root, "<tmp>"))

sp = [p for p in (os.path.join(env_dir, "Lib", "site-packages"),
                  os.path.join(env_dir, "lib")) if os.path.isdir(p)][0]
print("\nsite-packages 里和 mypkg 有关的条目：")
for n in sorted(os.listdir(sp)):
    if "mypkg" in n or "editable" in n.lower():
        print("  ", n)

with open(os.path.join(src, "__init__.py"), "w", encoding="utf-8") as fh:
    fh.write("VERSION = 'v2-改过没重装'\n")          # ⭐ 改源码，不重装
r = subprocess.run([py, "-c", "import mypkg; print(mypkg.VERSION)"],
                   capture_output=True, text=True, encoding="utf-8")
print("\n改完源码不重装，再 import：", r.stdout.strip())

# pycache.py —— .pyc 失效认的是「源文件 mtime（秒）+ 字节数」，不认内容
import os
import subprocess
import sys
import tempfile
import time

d = tempfile.mkdtemp()
mod, main = os.path.join(d, "conf.py"), os.path.join(d, "main.py")
with open(main, "w", encoding="utf-8") as fh:
    fh.write("import conf\nprint('VALUE =', conf.VALUE)\n")


def write(text):
    with open(mod, "w", encoding="utf-8") as fh:
        fh.write(text)


def run(tag):
    r = subprocess.run([sys.executable, "main.py"], cwd=d,
                       capture_output=True, text=True, encoding="utf-8")
    print(f"{tag} → {r.stdout.strip()}")


write("VALUE = 1\n")
run("① 首次导入            ")
print("   __pycache__ 里有：", os.listdir(os.path.join(d, "__pycache__")))
st = os.stat(mod)

write("VALUE = 2\n")                                  # 内容改了，字节数没变
os.utime(mod, (st.st_atime, st.st_mtime))             # ⭐ mtime 也还原
run("② 改内容 + 还原 mtime")

time.sleep(1.2)                                       # ⭐ 让 mtime 真的走过一秒
write("VALUE = 2\n")
run("③ 重写一次（mtime 变新）")

# 🧩 骨架：`os` 来自你自己的代码，这一段只看写法
ROOT    = r"C:\desktop\claude"                          # ← 硬编码，指向【老位置】
SCRATCH = os.path.dirname(os.path.abspath(__file__))    # ← 跟着脚本走，指向【新位置】

# roots.py —— 同一个脚本，从两个不同目录启动，两种路径写法的差别
import os
import subprocess
import sys
import tempfile

root = tempfile.mkdtemp()
tools = os.path.join(root, "tools")
elsewhere = os.path.join(root, "elsewhere")
os.makedirs(tools)
os.makedirs(elsewhere)
with open(os.path.join(tools, "build.py"), "w", encoding="utf-8") as fh:
    fh.write("import os\n"
             "print('  cwd                    =', os.getcwd())\n"
             "print('  abspath(\"out\")   [cwd] =', os.path.abspath('out'))\n"
             "here = os.path.dirname(os.path.abspath(__file__))\n"
             "print('  __file__ 推出来  [脚本] =', os.path.join(here, 'out'))\n")

for cwd in (tools, elsewhere):
    r = subprocess.run([sys.executable, os.path.join(tools, "build.py")],
                       cwd=cwd, capture_output=True, text=True, encoding="utf-8")
    print(f"--- 在 {os.path.basename(cwd)}/ 下启动")
    print(r.stdout.rstrip().replace(root, "<root>"))

import os

ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))   # ⭐ 「我上一级的上一级」
print("ROOT =", ROOT)