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創(chuàng)新互聯(lián)Python教程：venv—-創(chuàng)建虛擬環(huán)境

venv —- 創(chuàng)建虛擬環(huán)境

3.3 新版功能.

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源碼： Lib/venv/

The venv module supports creating lightweight “virtual environments”, each with their own independent set of python packages installed in their site directories. A virtual environment is created on top of an existing Python installation, known as the virtual environment’s “base” Python, and may optionally be isolated from the packages in the base environment, so only those explicitly installed in the virtual environment are available.

When used from within a virtual environment, common installation tools such as pip will install Python packages into a virtual environment without needing to be told to do so explicitly.

See PEP 405 for more background on Python virtual environments.

參見

Python 打包用戶指南：創(chuàng)建和使用虛擬環(huán)境

Availability: not Emscripten, not WASI.

This module does not work or is not available on WebAssembly platforms wasm32-emscripten and wasm32-wasi. See WebAssembly platforms for more information.

創(chuàng)建虛擬環(huán)境

通過執(zhí)行 venv 指令來創(chuàng)建一個虛擬環(huán)境:

 
 
 
 
  
  
  
  Python3 -m venv /path/to/new/virtual/environment

運(yùn)行此命令將創(chuàng)建目標(biāo)目錄（父目錄若不存在也將創(chuàng)建），并放置一個 pyvenv.cfg 文件在其中，文件中有一個 home 鍵，它的值指向運(yùn)行此命令的 Python 安裝（目標(biāo)目錄的常用名稱是 .venv）。它還會創(chuàng)建一個 bin 子目錄（在 Windows 上是 Scripts），其中包含 Python 二進(jìn)制文件的副本或符號鏈接（視創(chuàng)建環(huán)境時使用的平臺或參數(shù)而定）。它還會創(chuàng)建一個（初始為空的） lib/pythonX.Y/site-packages 子目錄（在 Windows 上是 Lib\site-packages）。如果指定了一個現(xiàn)有的目錄，這個目錄就將被重新使用。

3.6 版后已移除: pyvenv was the recommended tool for creating virtual environments for Python 3.3 and 3.4, and is deprecated in Python 3.6.

在 3.5 版更改: 現(xiàn)在推薦使用 venv 來創(chuàng)建虛擬環(huán)境。

在 Windows 上，調(diào)用 venv 命令如下:

 
 
 
 
  
  
  
  c:\>c:\Python35\python -m venv c:\path\to\myenv

或者，如果已經(jīng)為 Python 安裝配置好 PATH 和 PATHEXT 變量:

 
 
 
 
  
  
  
  c:\>python -m venv c:\path\to\myenv

本命令如果以 -h 參數(shù)運(yùn)行，將顯示可用的選項(xiàng):

 
 
 
 
  
  
  
  usage: venv [-h] [--system-site-packages] [--symlinks | --copies] [--clear]  
  
  
   [--upgrade] [--without-pip] [--prompt PROMPT] [--upgrade-deps]  
  
  
   ENV_DIR [ENV_DIR ...]  
  
  
    
  
  
  Creates virtual Python environments in one or more target directories.  
  
  
    
  
  
  positional arguments:  
  
  
   ENV_DIR A directory to create the environment in.  
  
  
    
  
  
  optional arguments:  
  
  
   -h, --help show this help message and exit  
  
  
   --system-site-packages  
  
  
   Give the virtual environment access to the system  
  
  
   site-packages dir.  
  
  
   --symlinks Try to use symlinks rather than copies, when symlinks  
  
  
   are not the default for the platform.  
  
  
   --copies Try to use copies rather than symlinks, even when  
  
  
   symlinks are the default for the platform.  
  
  
   --clear Delete the contents of the environment directory if it  
  
  
   already exists, before environment creation.  
  
  
   --upgrade Upgrade the environment directory to use this version  
  
  
   of Python, assuming Python has been upgraded in-place.  
  
  
   --without-pip Skips installing or upgrading pip in the virtual  
  
  
   environment (pip is bootstrapped by default)  
  
  
   --prompt PROMPT Provides an alternative prompt prefix for this  
  
  
   environment.  
  
  
   --upgrade-deps Upgrade core dependencies: pip setuptools to the  
  
  
   latest version in PyPI  
  
  
    
  
  
  Once an environment has been created, you may wish to activate it, e.g. by  
  
  
  sourcing an activate script in its bin directory.

在 3.9 版更改: 添加 --upgrade-deps 選項(xiàng)，用于將 pip + setuptools 升級到 PyPI 上的最新版本

在 3.4 版更改: 默認(rèn)安裝 pip，并添加 --without-pip 和 --copies 選項(xiàng)

在 3.4 版更改: 在早期版本中，如果目標(biāo)目錄已存在，將引發(fā)錯誤，除非使用了 --clear 或 --upgrade 選項(xiàng)。

備注

雖然 Windows 支持符號鏈接，但不推薦使用它們。特別注意，在文件資源管理器中雙擊 python.exe 將立即解析符號鏈接，并忽略虛擬環(huán)境。

備注

在 Microsoft Windows 上，為了啟用 Activate.ps1 腳本，可能需要修改用戶的執(zhí)行策略?？梢赃\(yùn)行以下 PowerShell 命令來執(zhí)行此操作：

PS C:> Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser

參閱 About Execution Policies 以獲取更多信息。

生成的 pyvenv.cfg 文件還包括 include-system-site-packages 鍵，如果運(yùn)行 venv 時帶有 --system-site-packages 選項(xiàng)，則鍵值為 true，否則為 false。

除非采用 --without-pip 選項(xiàng)，否則將會調(diào)用 ensurepip 將 pip 引導(dǎo)到虛擬環(huán)境中。

可以向 venv 傳入多個路徑，此時將根據(jù)給定的選項(xiàng)，在所給的每個路徑上創(chuàng)建相同的虛擬環(huán)境。

How venvs work

When a Python interpreter is running from a virtual environment, sys.prefix and sys.exec_prefix point to the directories of the virtual environment, whereas sys.base_prefix and sys.base_exec_prefix point to those of the base Python used to create the environment. It is sufficient to check sys.prefix == sys.base_prefix to determine if the current interpreter is running from a virtual environment.

A virtual environment may be “activated” using a script in its binary directory (bin on POSIX; Scripts on Windows). This will prepend that directory to your PATH, so that running !python will invoke the environment’s Python interpreter and you can run installed scripts without having to use their full path. The invocation of the activation script is platform-specific (** must be replaced by the path to the directory containing the virtual environment):

平臺	Shell	用于激活虛擬環(huán)境的命令
POSIX	bash/zsh	`$ source /bin/activate`
	fish	`$ source /bin/activate.fish`
	csh/tcsh	`$ source /bin/activate.csh`
	PowerShell	`$ /bin/Activate.ps1`
Windows	cmd.exe	`C:\> \Scripts\activate.bat`
Windows	PowerShell	`PS C:\> \Scripts\Activate.ps1`

3.4 新版功能: !fish and !csh activation scripts.

3.8 新版功能: 在 POSIX 上安裝 PowerShell 激活腳本，以支持 PowerShell Core。

You don’t specifically need to activate a virtual environment, as you can just specify the full path to that environment’s Python interpreter when invoking Python. Furthermore, all scripts installed in the environment should be runnable without activating it.

In order to achieve this, scripts installed into virtual environments have a “shebang” line which points to the environment’s Python interpreter, i.e. #!/**/bin/python. This means that the script will run with that interpreter regardless of the value of PATH. On Windows, “shebang” line processing is supported if you have the 適用于Windows的Python啟動器 installed. Thus, double-clicking an installed script in a Windows Explorer window should run it with the correct interpreter without the environment needing to be activated or on the PATH.

When a virtual environment has been activated, the VIRTUAL_ENV environment variable is set to the path of the environment. Since explicitly activating a virtual environment is not required to use it, VIRTUAL_ENV cannot be relied upon to determine whether a virtual environment is being used.

警告

Because scripts installed in environments should not expect the environment to be activated, their shebang lines contain the absolute paths to their environment’s interpreters. Because of this, environments are inherently non-portable, in the general case. You should always have a simple means of recreating an environment (for example, if you have a requirements file requirements.txt, you can invoke pip install -r requirements.txt using the environment’s pip to install all of the packages needed by the environment). If for any reason you need to move the environment to a new location, you should recreate it at the desired location and delete the one at the old location. If you move an environment because you moved a parent directory of it, you should recreate the environment in its new location. Otherwise, software installed into the environment may not work as expected.

You can deactivate a virtual environment by typing deactivate in your shell. The exact mechanism is platform-specific and is an internal implementation detail (typically, a script or shell function will be used).

API

上述的高級方法使用了一個簡單的 API，該 API 提供了一種機(jī)制，第三方虛擬環(huán)境創(chuàng)建者可以根據(jù)其需求自定義環(huán)境創(chuàng)建過程，該 API 為 EnvBuilder 類。

class venv.EnvBuilder(system_site_packages=False, clear=False, symlinks=False, upgrade=False, with_pip=False, prompt=None, upgrade_deps=False)

EnvBuilder 類在實(shí)例化時接受以下關(guān)鍵字參數(shù)：

system_site_packages — 一個布爾值，要求系統(tǒng) Python 的 site-packages 對環(huán)境可用（默認(rèn)為 False）。
clear — 一個布爾值，如果為 true，則在創(chuàng)建環(huán)境前將刪除目標(biāo)目錄的現(xiàn)有內(nèi)容。
symlinks — 一個布爾值，指示是否嘗試符號鏈接 Python 二進(jìn)制文件，而不是進(jìn)行復(fù)制。
upgrade — 一個布爾值，如果為 true，則將使用當(dāng)前運(yùn)行的 Python 去升級一個現(xiàn)有的環(huán)境，這主要在原位置的 Python 更新后使用（默認(rèn)為 False）。
with_pip — 一個布爾值，如果為 true，則確保在虛擬環(huán)境中已安裝 pip。這使用的是帶有 --default-pip 選項(xiàng)的 ensurepip。
prompt — 激活虛擬環(huán)境后顯示的提示符（默認(rèn)為 None，表示使用環(huán)境所在的目錄名稱）。如果使用了 "." 這一特殊字符串，則使用當(dāng)前目錄的基本名稱作為提示符。
upgrade_deps — 將基本 venv 模塊更新為 PyPI 上的最新版本。

在 3.4 版更改: 添加 with_pip 參數(shù)

3.6 新版功能: 添加 prompt 參數(shù)

3.9 新版功能: 添加 upgrade_deps 參數(shù)

第三方虛擬環(huán)境工具的創(chuàng)建者可以自由地將此處提供的 EnvBuilder 類作為基類。

返回的 env-builder 是一個對象，包含一個 create 方法：

create(env_dir)

指定要建立虛擬環(huán)境的目標(biāo)目錄（絕對路徑或相對于當(dāng)前路徑）來創(chuàng)建虛擬環(huán)境。create 方法將在指定目錄中創(chuàng)建環(huán)境，或者引發(fā)對應(yīng)的異常。

EnvBuilder 類的 create 方法定義了可用于定制子類的鉤子:

   
   
   
   
    
    
    
    def create(self, env_dir):    
    
    
     """    
    
    
     Create a virtualized Python environment in a directory.    
    
    
     env_dir is the target directory to create an environment in.    
    
    
     """    
    
    
     env_dir = os.path.abspath(env_dir)    
    
    
     context = self.ensure_directories(env_dir)    
    
    
     self.create_configuration(context)    
    
    
     self.setup_python(context)    
    
    
     self.setup_scripts(context)    
    
    
     self.post_setup(context)

每個方法 ensure_directories(), create_configuration(), setup_python(), setup_scripts() 和 post_setup() 都可以被重寫。

ensure_directories(env_dir)
Creates the environment directory and all necessary subdirectories that don’t already exist, and returns a context object. This context object is just a holder for attributes (such as paths) for use by the other methods. If the EnvBuilder is created with the arg clear=True, contents of the environment directory will be cleared and then all necessary subdirectories will be recreated.
The returned context object is a types.SimpleNamespace with the following attributes:
- env_dir - The location of the virtual environment. Used for __VENV_DIR__ in activation scripts (see install_scripts()).
- env_name - The name of the virtual environment. Used for __VENV_NAME__ in activation scripts (see install_scripts()).
- prompt - The prompt to be used by the activation scripts. Used for __VENV_PROMPT__ in activation scripts (see install_scripts()).
- executable - The underlying Python executable used by the virtual environment. This takes into account the case where a virtual environment is created from another virtual environment.
- inc_path - The include path for the virtual environment.
- lib_path - The purelib path for the virtual environment.
- bin_path - The script path for the virtual environment.
- bin_name - The name of the script path relative to the virtual environment location. Used for __VENV_BIN_NAME__ in activation scripts (see install_scripts()).
- env_exe - The name of the Python interpreter in the virtual environment. Used for __VENV_PYTHON__ in activation scripts (see install_scripts()).
- env_exec_cmd - The name of the Python interpreter, taking into account filesystem redirections. This can be used to run Python in the virtual environment.
在 3.12 版更改: The attribute lib_path was added to the context, and the context object was documented.
在 3.11 版更改: The venv sysconfig installation scheme is used to construct the paths of the created directories.
create_configuration(context)
在環(huán)境中創(chuàng)建 pyvenv.cfg 配置文件。
setup_python(context)
在環(huán)境中創(chuàng)建 Python 可執(zhí)行文件的拷貝或符號鏈接。在 POSIX 系統(tǒng)上，如果給定了可執(zhí)行文件 python3.x，將創(chuàng)建指向該可執(zhí)行文件的 python 和 python3 符號鏈接，除非相同名稱的文件已經(jīng)存在。
setup_scripts(context)
將適用于平臺的激活腳本安裝到虛擬環(huán)境中。
upgrade_dependencies(context)
升級環(huán)境中 venv 依賴的核心軟件包（當(dāng)前為 pip 和 setuptools）。通過在環(huán)境中使用 pip 可執(zhí)行文件來完成。
3.9 新版功能.
post_setup(context)
占位方法，可以在第三方實(shí)現(xiàn)中重寫，用于在虛擬環(huán)境中預(yù)安裝軟件包，或是其他創(chuàng)建后要執(zhí)行的步驟。

在 3.7.2 版更改: Windows 現(xiàn)在為 python[w].exe 使用重定向腳本，而不是復(fù)制實(shí)際的二進(jìn)制文件。僅在 3.7.2 中，除非運(yùn)行的是源碼樹中的構(gòu)建，否則 setup_python() 不會執(zhí)行任何操作。

在 3.7.3 版更改: Windows 將重定向腳本復(fù)制為 setup_python() 的一部分而非 setup_scripts()。在 3.7.2 中不是這種情況。使用符號鏈接時，將鏈接至原始可執(zhí)行文件。

此外，EnvBuilder 提供了如下實(shí)用方法，可以從子類的 setup_scripts() 或 post_setup() 調(diào)用，用來將自定義腳本安裝到虛擬環(huán)境中。

install_scripts(context, path)
path 是一個目錄的路徑，該目錄應(yīng)包含子目錄 “common”, “posix”, “nt”，每個子目錄存有發(fā)往對應(yīng)環(huán)境中 bin 目錄的腳本。在下列占位符替換完畢后，將復(fù)制 “common” 的內(nèi)容和與 os.name 對應(yīng)的子目錄：
- __VENV_DIR__ 會被替換為環(huán)境目錄的絕對路徑。
- __VENV_NAME__ 會被替換為環(huán)境名稱（環(huán)境目錄的最后一個字段）。
- __VENV_PROMPT__ 會被替換為提示符（用括號括起來的環(huán)境名稱緊跟著一個空格）。
- __VENV_BIN_NAME__ 會被替換為 bin 目錄的名稱（ bin 或 Scripts ）。
- __VENV_PYTHON__ 會被替換為環(huán)境可執(zhí)行文件的絕對路徑。
允許目錄已存在（用于升級現(xiàn)有環(huán)境時）。

有一個方便實(shí)用的模塊級別的函數(shù):

venv.create(env_dir, system_site_packages=False, clear=False, symlinks=False, with_pip=False, prompt=None, upgrade_deps=False)

通過關(guān)鍵詞參數(shù)來創(chuàng)建一個 EnvBuilder，并且使用 env_dir 參數(shù)來調(diào)用它的 create() 方法。

3.3 新版功能.

在 3.4 版更改: 添加 with_pip 參數(shù)

在 3.6 版更改: 添加 prompt 參數(shù)

在 3.9 版更改: 添加 upgrade_deps 參數(shù)

一個擴(kuò)展 `EnvBuilder` 的例子

下面的腳本展示了如何通過實(shí)現(xiàn)一個子類來擴(kuò)展 EnvBuilder。這個子類會安裝 setuptools 和 pip 到被創(chuàng)建的虛擬環(huán)境中。

 
 
 
 
  
  
  
  import os  
  
  
  import os.path  
  
  
  from subprocess import Popen, PIPE  
  
  
  import sys  
  
  
  from threading import Thread  
  
  
  from urllib.parse import urlparse  
  
  
  from urllib.request import urlretrieve  
  
  
  import venv  
  
  
    
  
  
  class ExtendedEnvBuilder(venv.EnvBuilder):  
  
  
   """  
  
  
   This builder installs setuptools and pip so that you can pip or  
  
  
   easy_install other packages into the created virtual environment.  
  
  
    
  
  
   :param nodist: If true, setuptools and pip are not installed into the  
  
  
   created virtual environment.  
  
  
   :param nopip: If true, pip is not installed into the created  
  
  
   virtual environment.  
  
  
   :param progress: If setuptools or pip are installed, the progress of the  
  
  
   installation can be monitored by passing a progress  
  
  
   callable. If specified, it is called with two  
  
  
   arguments: a string indicating some progress, and a  
  
  
   context indicating where the string is coming from.  
  
  
   The context argument can have one of three values:  
  
  
   'main', indicating that it is called from virtualize()  
  
  
   itself, and 'stdout' and 'stderr', which are obtained  
  
  
   by reading lines from the output streams of a subprocess  
  
  
   which is used to install the app.  
  
  
    
  
  
   If a callable is not specified, default progress  
  
  
   information is output to sys.stderr.  
  
  
   """  
  
  
    
  
  
   def __init__(self, *args, **kwargs):  
  
  
   self.nodist = kwargs.pop('nodist', False)  
  
  
   self.nopip = kwargs.pop('nopip', False)  
  
  
   self.progress = kwargs.pop('progress', None)  
  
  
   self.verbose = kwargs.pop('verbose', False)  
  
  
   super().__init__(*args, **kwargs)  
  
  
    
  
  
   def post_setup(self, context):  
  
  
   """  
  
  
   Set up any packages which need to be pre-installed into the  
  
  
   virtual environment being created.  
  
  
    
  
  
   :param context: The information for the virtual environment  
  
  
   creation request being processed.  
  
  
   """  
  
  
   os.environ['VIRTUAL_ENV'] = context.env_dir  
  
  
   if not self.nodist:  
  
  
   self.install_setuptools(context)  
  
  
   # Can't install pip without setuptools  
  
  
   if not self.nopip and not self.nodist:  
  
  
   self.install_pip(context)  
  
  
    
  
  
   def reader(self, stream, context):  
  
  
   """  
  
  
   Read lines from a subprocess' output stream and either pass to a progress  
  
  
   callable (if specified) or write progress information to sys.stderr.  
  
  
   """  
  
  
   progress = self.progress  
  
  
   while True:  
  
  
   s = stream.readline()  
  
  
   if not s:  
  
  
   break  
  
  
   if progress is not None:  
  
  
   progress(s, context)  
  
  
   else:  
  
  
   if not self.verbose:  
  
  
   sys.stderr.write('.')  
  
  
   else:  
  
  
   sys.stderr.write(s.decode('utf-8'))  
  
  
   sys.stderr.flush()  
  
  
   stream.close()  
  
  
    
  
  
   def install_script(self, context, name, url):  
  
  
   _, _, path, _, _, _ = urlparse(url)  
  
  
   fn = os.path.split(path)[-1]  
  
  
   binpath = context.bin_path  
  
  
   distpath = os.path.join(binpath, fn)  
  
  
   # Download script into the virtual environment's binaries folder  
  
  
   urlretrieve(url, distpath)  
  
  
   progress = self.progress  
  
  
   if self.verbose:  
  
  
   term = '\n'  
  
  
   else:  
  
  
   term = ''  
  
  
   if progress is not None:  
  
  
   progress('Installing %s ...%s' % (name, term), 'main')  
  
  
   else:  
  
  
   sys.stderr.write('Installing %s ...%s' % (name, term))  
  
  
   sys.stderr.flush()  
  
  
   # Install in the virtual environment  
  
  
   args = [context.env_exe, fn]  
  
  
   p = Popen(args, stdout=PIPE, stderr=PIPE, cwd=binpath)  
  
  
   t1 = Thread(target=self.reader, args=(p.stdout, 'stdout'))  
  
  
   t1.start()  
  
  
   t2 = Thread(target=self.reader, args=(p.stderr, 'stderr'))  
  
  
   t2.start()  
  
  
   p.wait()  
  
  
   t1.join()  
  
  
   t2.join()  
  
  
   if progress is not None:  
  
  
   progress('done.', 'main')  
  
  
   else:  
  
  
   sys.stderr.write('done.\n')  
  
  
   # Clean up - no longer needed  
  
  
   os.unlink(distpath)  
  
  
    
  
  
   def install_setuptools(self, context):  
  
  
   """  
  
  
   Install setuptools in the virtual environment.  
  
  
    
  
  
   :param context: The information for the virtual environment  
  
  
   creation request being processed.  
  
  
   """  
  
  
   url = 'https://bitbucket.org/pypa/setuptools/downloads/ez_setup.py'  
  
  
   self.install_script(context, 'setuptools', url)  
  
  
   # clear up the setuptools archive which gets downloaded  
  
  
   pred = lambda o: o.startswith('setuptools-') and o.endswith('.tar.gz')  
  
  
   files = filter(pred, os.listdir(context.bin_path))  
  
  
   for f in files:  
  
  
   f = os.path.join(context.bin_path, f)  
  
  
   os.unlink(f)  
  
  
    
  
  
   def install_pip(self, context):  
  
  
   """  
  
  
   Install pip in the virtual environment.  
  
  
    
  
  
   :param context: The information for the virtual environment  
  
  
   creation request being processed.  
  
  
   """  
  
  
   url = 'https://bootstrap.pypa.io/get-pip.py'  
  
  
   self.install_script(context, 'pip', url)  
  
  
    
  
  
  def main(args=None):  
  
  
   compatible = True  
  
  
   if sys.version_info < (3, 3):  
  
  
   compatible = False  
  
  
   elif not hasattr(sys, 'base_prefix'):  
  
  
   compatible = False  
  
  
   if not compatible:  
  
  
   raise ValueError('This script is only for use with '  
  
  
   'Python 3.3 or later')  
  
  
   else:  
  
  
   import argparse  
  
  
    
  
  
   parser = argparse.ArgumentParser(prog=__name__,  
  
  
   description='Creates virtual Python '  
  
  
   'environments in one or '  
  
  
   'more target '  
  
  
   'directories.')  
  
  
   parser.add_argument('dirs', metavar='ENV_DIR', nargs='+',  
  
  
   help='A directory in which to create the '  
  
  
   'virtual environment.')  
  
  
   parser.add_argument('--no-setuptools', default=False,  
  
  
   action='store_true', dest='nodist',  
  
  
   help="Don't install setuptools or pip in the "  
  
  
   "virtual environment.")  
  
  
   parser.add_argument('--no-pip', default=False,  
  
  
   action='store_true', dest='nopip',  
  
  
   help="Don't install pip in the virtual "  
  
  
   "environment.")  
  
  
   parser.add_argument('--system-site-packages', default=False,  
  
  
   action='store_true', dest='system_site',  
  
  
   help='Give the virtual environment access to the '  
  
  
   'system site-packages dir.')  
  
  
   if os.name == 'nt':  
  
  
   use_symlinks = False  
  
  
   else:  
  
  
   use_symlinks = True  
  
  
   parser.add_argument('--symlinks', default=use_symlinks,  
  
  
   action='store_true', dest='symlinks',  
  
  
   help='Try to use symlinks rather than copies, '  
  
  
   'when symlinks are not the default for '  
  
  
   'the platform.')  
  
  
   parser.add_argument('--clear', default=False, action='store_true',  
  
  
   dest='clear', help='Delete the contents of the '  
  
  
   'virtual environment '  
  
  
   'directory if it already '  
  
  
   'exists, before virtual '  
  
  
   'environment creation.')  
  
  
   parser.add_argument('--upgrade', default=False, action='store_true',  
  
  
   dest='upgrade', help='Upgrade the virtual '  
  
  
   'environment directory to '  
  
  
   'use this version of '  
  
  
   'Python, assuming Python '  
  
  
   'has been upgraded '  
  
  
   'in-place.')  
  
  
   parser.add_argument('--verbose', default=False, action='store_true',  
  
  
   dest='verbose', help='Display the output '  
  
  
   'from the scripts which '  
  
  
   'install setuptools and pip.')  
  
  
   options = parser.parse_args(args)  
  
  
   if options.upgrade and options.clear:  
  
  
   raise ValueError('you cannot supply --upgrade and --clear together.')  
  
  
   builder = ExtendedEnvBuilder(system_site_packages=options.system_site,  
  
  
   clear=options.clear,  
  
  
   symlinks=options.symlinks,  
  
  
   upgrade=options.upgrade,  
  
  
   nodist=options.nodist,  
  
  
   nopip=options.nopip,  
  
  
   verbose=options.verbose)  
  
  
   for d in options.dirs:  
  
  
   builder.create(d)  
  
  
    
  
  
  if __name__ == '__main__':  
  
  
   rc = 1  
  
  
   try:  
  
  
   main()  
  
  
   rc = 0  
  
  
   except Exception as e:  
  
  
   print('Error: %s' % e, file=sys.stderr)  
  
  
   sys.exit(rc)

這個腳本同樣可以在線下載。

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新聞中心

venv —- 創(chuàng)建虛擬環(huán)境

創(chuàng)建虛擬環(huán)境

How venvs work

API

一個擴(kuò)展 `EnvBuilder` 的例子

其他資訊

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新聞中心

venv —- 創(chuàng)建虛擬環(huán)境

創(chuàng)建虛擬環(huán)境

How venvs work

API

一個擴(kuò)展 EnvBuilder 的例子

其他資訊

一個擴(kuò)展 `EnvBuilder` 的例子