创建虚拟环境时，传递给venv.create（）的参数无效

Question

I'm working on a PyQt5 wizard to create Python virtual environments. Creating the environment works. The arguments (for example, with or without pip , ...) are passed from a QCheckBox() to the create() function of the venv module that comes with Python.

The problem is that the arguments passed to venv.create() have no effect on the creation of the virtual environment. It is always created with the default settings (for example, pip is installed by default).

But if I pass with_pip=False directly, pip will not be installed. That means, for some reason, the arguments passed from args have no effect on the creation. I tried converting the values into bool() , but that didn't work.

It is not clear to me why, because print(args) outputs True or False (as strings), depending on the isChecked() status of the corresponding QCheckBox() .

Further, I'm using location and name (in args ) to build the path to where the virtual environment will be installed, and this works fine.

Can somebody explain why venv.create() doesn't accept the arguments comming from isChecked() of the QCheckBox() ? Or am I missing something?

---

Code to reproduce:

from subprocess import Popen, PIPE, CalledProcessError
from functools import partial
import venv
import os

from PyQt5 import QtWidgets, QtGui, QtCore
from PyQt5.QtGui import QIcon
from PyQt5.QtCore import Qt, QObject, QTimer, QThread, pyqtSignal, pyqtSlot
from PyQt5.QtWidgets import (QApplication, QFileDialog, QGridLayout, QLabel,
                             QVBoxLayout, QWizard, QWizardPage, QProgressBar,
                             QCheckBox, QLineEdit, QGroupBox, QToolButton,
                             QComboBox, QDialog, QHBoxLayout)



#]===========================================================================[#
#] FIND INSTALLED INTERPRETERS [#============================================[#
#]===========================================================================[#

# look for installed Python 3 versions
versions = ['3.9', '3.8', '3.7', '3.6', '3.5', '3.4', '3.3', '3']

notFound = []
versFound = []
pathFound = []

for i, v in enumerate(versions):
    try:
        # get installed python3 versions
        getVers = Popen(["python" + v, "-V"],
                            stdout=PIPE, universal_newlines=True)
        version = getVers.communicate()[0].strip()

        # get paths of the python executables
        getPath = Popen(["which", "python" + v],
                            stdout=PIPE, universal_newlines=True)
        path = getPath.communicate()[0].strip()

        versFound.append(version)
        pathFound.append(path)

    except (CalledProcessError, FileNotFoundError):
        notFound.append(i)


#]===========================================================================[#
#] PROGRESS BAR [#===========================================================[#
#]===========================================================================[#

class ProgBarWidget(QDialog):
    """
    The dialog that shows a progress bar during the create process.
    """
    def __init__(self):
        super().__init__()
        self.initMe()

    def initMe(self):
        self.setGeometry(690, 365, 325, 80)
        self.setFixedSize(325, 80)
        self.setWindowTitle("Creating")
        self.setWindowFlag(Qt.WindowCloseButtonHint, False)
        self.setWindowFlag(Qt.WindowMinimizeButtonHint, False)

        horizontalLayout = QHBoxLayout(self)
        verticalLayout = QVBoxLayout()

        statusLabel = QLabel(self)
        statusLabel.setText("Creating virtual environment...")

        self.progressBar = QProgressBar(self)
        self.progressBar.setFixedSize(300, 23)
        self.progressBar.setRange(0, 0)

        verticalLayout.addWidget(statusLabel)
        verticalLayout.addWidget(self.progressBar)

        horizontalLayout.addLayout(verticalLayout)
        self.setLayout(horizontalLayout)

---

#]===========================================================================[#
#] VENV WIZARD [#============================================================[#
#]===========================================================================[#

class VenvWizard(QWizard):
    """
    Wizard for creating and setting up virtual environments.
    """
    def __init__(self):
        super().__init__()

        self.setWindowTitle("Venv Wizard")
        self.resize(535, 430)
        self.move(578, 183)

        self.setStyleSheet(
            """
            QToolTip {
                background-color: rgb(47, 52, 63);
                border: rgb(47, 52, 63);
                color: rgb(210, 210, 210);
                padding: 2px;
                opacity: 325
            }
            """
        )

        self.addPage(BasicSettings())
        self.addPage(InstallPackages())
        self.addPage(Summary())


class BasicSettings(QWizardPage):
    """
    Basic settings of the virtual environment being created.
    """
    def __init__(self):
        super().__init__()

        folder_icon = QIcon.fromTheme("folder")

        self.setTitle("Basic Settings")
        self.setSubTitle("This wizard will help you to create and set up "
                         "a virtual environment for Python 3. ")


        #]===================================================================[#
        #] PAGE CONTENT [#===================================================[#
        #]===================================================================[#

        interpreterLabel = QLabel("&Interpreter:")
        self.interprComboBox = QComboBox()
        interpreterLabel.setBuddy(self.interprComboBox)

        # add items from versFound to combobox
        self.interprComboBox.addItem("---")
        for i in range(len(versFound)):
            self.interprComboBox.addItem(versFound[i], pathFound[i])

        venvNameLabel = QLabel("Venv &name:")
        self.venvNameLineEdit = QLineEdit()
        venvNameLabel.setBuddy(self.venvNameLineEdit)

        venvLocationLabel = QLabel("&Location:")
        self.venvLocationLineEdit = QLineEdit()
        venvLocationLabel.setBuddy(self.venvLocationLineEdit)

        selectFolderToolButton = QToolButton()
        selectFolderToolButton.setFixedSize(26, 27)
        selectFolderToolButton.setIcon(folder_icon)
        selectFolderToolButton.setToolTip("Browse")

        placeHolder = QLabel()

        # the 'options' groupbox
        groupBox = QGroupBox("Options")

        self.withPipCBox = QCheckBox("Install and update &Pip")
        self.sitePackagesCBox = QCheckBox(
            "&Make system (global) site-packages dir available to venv")
        self.launchVenvCBox = QCheckBox(
            "Launch a terminal with activated &venv after installation")
        self.symlinksCBox = QCheckBox(
            "Attempt to &symlink rather than copy files into venv")

        # events
        self.withPipCBox.toggled.connect(self.collectData)
        self.sitePackagesCBox.toggled.connect(self.collectData)
        self.launchVenvCBox.toggled.connect(self.collectData)
        self.venvNameLineEdit.textChanged.connect(self.collectData)
        self.venvLocationLineEdit.textChanged.connect(self.collectData)
        self.interprComboBox.currentIndexChanged.connect(self.collectData)
        self.symlinksCBox.toggled.connect(self.collectData)
        selectFolderToolButton.clicked.connect(self.selectDir)

        # store the collected data in line edits
        self.interprVers = QLineEdit()
        self.interprPath = QLineEdit()
        self.venvName = QLineEdit()
        self.venvLocation = QLineEdit()
        self.withPip = QLineEdit()
        self.sitePackages = QLineEdit()
        self.launchVenv = QLineEdit()
        self.symlinks = QLineEdit()

        # register fields
        self.registerField("interprComboBox*", self.interprComboBox)
        self.registerField("venvNameLineEdit*", self.venvNameLineEdit)
        self.registerField("venvLocationLineEdit*", self.venvLocationLineEdit)
        self.registerField("interprVers", self.interprVers)
        self.registerField("interprPath", self.interprPath)
        self.registerField("venvName", self.venvName)
        self.registerField("venvLocation", self.venvLocation)
        self.registerField("withPip", self.withPip)
        self.registerField("sitePackages", self.sitePackages)
        self.registerField("launchVenv", self.launchVenv)
        self.registerField("symlinks", self.symlinks)

        # grid layout
        gridLayout = QGridLayout()
        gridLayout.addWidget(interpreterLabel, 0, 0, 1, 1)
        gridLayout.addWidget(self.interprComboBox, 0, 1, 1, 2)
        gridLayout.addWidget(venvNameLabel, 1, 0, 1, 1)
        gridLayout.addWidget(self.venvNameLineEdit, 1, 1, 1, 2)
        gridLayout.addWidget(venvLocationLabel, 2, 0, 1, 1)
        gridLayout.addWidget(self.venvLocationLineEdit, 2, 1, 1, 1)
        gridLayout.addWidget(selectFolderToolButton, 2, 2, 1, 1)
        gridLayout.addWidget(placeHolder, 3, 0, 1, 2)
        gridLayout.addWidget(groupBox, 4, 0, 1, 3)
        self.setLayout(gridLayout)

        # 'options' groupbox
        groupBoxLayout = QVBoxLayout()
        groupBoxLayout.addWidget(self.withPipCBox)
        groupBoxLayout.addWidget(self.sitePackagesCBox)
        groupBoxLayout.addWidget(self.launchVenvCBox)
        groupBoxLayout.addWidget(self.symlinksCBox)
        groupBox.setLayout(groupBoxLayout)


    #]=======================================================================[#
    #] SELECTIONS [#=========================================================[#
    #]=======================================================================[#

    def selectDir(self):
        """
        Specify path where to create venv.
        """
        folderName = QFileDialog.getExistingDirectory()
        self.venvLocationLineEdit.setText(folderName)

    def collectData(self, i):
        """
        Collect all input data and create the virtual environment.
        """
        self.interprVers.setText(self.interprComboBox.currentText())
        self.interprPath.setText(self.interprComboBox.currentData())
        self.venvName.setText(self.venvNameLineEdit.text())
        self.venvLocation.setText(self.venvLocationLineEdit.text())

        # the 'options'
        self.withPip.setText(str(self.withPipCBox.isChecked()))
        self.sitePackages.setText(str(self.sitePackagesCBox.isChecked()))
        self.launchVenv.setText(str(self.launchVenvCBox.isChecked()))
        self.symlinks.setText(str(self.symlinksCBox.isChecked()))

---

#]===========================================================================[#
#] WORKER  [#================================================================[#
#]===========================================================================[#

class InstallWorker(QObject):
    """
    Worker informing about start and finish of the create process.
    """
    started = pyqtSignal()
    finished = pyqtSignal()

    @pyqtSlot(tuple)
    def install(self, args):
        self.started.emit()

        name, location, with_pip, site_packages, symlinks = args
        # outputs as excpected
        #print(args)
        #print("pip:", args[2], "\nsite-pkgs:", args[3], "\nsymlinks:", args[4])

        venv.create(
            os.path.join(location, name),  # 'location' and 'name' works
            with_pip=with_pip,  # installs pip always (the default)
            system_site_packages=site_packages,  # not tested yet
            symlinks=symlinks,  # never symlinking
        )

        self.finished.emit()

---

class InstallPackages(QWizardPage):
    """
    Install packages via `pip` into the created virtual environment.
    """
    def __init__(self):
        super().__init__()

        self.setTitle("Install Packages")
        self.setSubTitle("Specify the packages which you want Pip to "
                         "install into the virtual environment.")

        self.progressBar = ProgBarWidget()


        #]===================================================================[#
        #] THREAD  [#========================================================[#
        #]===================================================================[#

        thread = QThread(self)
        thread.start()

        self.m_install_worker = InstallWorker()
        self.m_install_worker.moveToThread(thread)

        self.m_install_worker.started.connect(self.progressBar.exec_)
        self.m_install_worker.finished.connect(self.progressBar.close)
        self.m_install_worker.finished.connect(self.reEnablePage)


        #]===================================================================[#
        #] PAGE CONTENT [#===================================================[#
        #]===================================================================[#

        # just some test content (page is still in development)
        TestLabel = QLabel("This is a test label:", self)
        TestLineEdit = QLineEdit(self)
        TestLabel.setBuddy(TestLineEdit)

        TestLabel2 = QLabel("This is a test label:", self)
        TestLineEdit2 = QLineEdit(self)
        TestLabel2.setBuddy(TestLineEdit2)

        v_layout = QVBoxLayout(self)
        v_layout.addWidget(TestLabel)
        v_layout.addWidget(TestLineEdit)
        v_layout.addWidget(TestLabel2)
        v_layout.addWidget(TestLineEdit2)
        self.setLayout(v_layout)


    def initializePage(self):
        #interprVers = self.field("interprVers")
        self.interprPath = self.field("interprPath")
        self.venvName = self.field("venvName")
        self.venvLocation = self.field("venvLocation")
        self.withPip = self.field("withPip")
        self.sitePackages = self.field("sitePackages")
        #launchVenv = self.field("launchVenv")
        self.symlinks = self.field("symlinks")

        # set the selected interpreter
        sys.executable = self.interprPath

        # run the create process
        self.createProcess()

        # disable the page as long as the progress bar is up
        self.setEnabled(False)


    def reEnablePage(self):
        """
        Re-enable page after the create process has finished.
        """
        self.setEnabled(True)


    def createProcess(self):
        """
        Create the virtual environment.
        """
        args = (
            self.venvName,
            self.venvLocation,
            self.withPip,
            self.sitePackages,
            self.symlinks,
        )

        wrapper = partial(self.m_install_worker.install, args)
        QTimer.singleShot(0, wrapper)



class Summary(QWizardPage):
    def __init__(self):
        super().__init__()

        self.setTitle("Summary")
        self.setSubTitle("...............")



if __name__ == "__main__":
    import sys

    app = QApplication(sys.argv)

    wizard = VenvWizard()
    wizard.show()

    sys.exit(app.exec_())

Answer 1

You are creating QLineEdit just to save data that is unnecessary since you can register widget properties as the status of the checkbox. You are also converting the Boolean True or False to the string "True" or "False", respectively, which you then pass to the function venv.create() that will convert it to boolean but any string not empty is truly.

The solution is to register the QCheckBox directly, in addition to the other widgets.

class BasicSettings(QWizardPage):
    """
    Basic settings of the virtual environment being created.
    """

    def __init__(self):
        super().__init__()

        # ...
        groupBox.setLayout(groupBoxLayout)

        selectFolderToolButton.clicked.connect(self.selectDir)

        self.registerField("interprVers", self.interprComboBox, "currentText")
        self.registerField("interprPath", self.interprComboBox, "currentData")
        self.registerField("venvName", self.venvNameLineEdit)
        self.registerField("venvLocation", self.venvLocationLineEdit)

        self.registerField("withPip", self.withPipCBox)
        self.registerField("sitePackages", self.sitePackagesCBox)
        self.registerField("launchVenv", self.launchVenvCBox)
        self.registerField("symlinks", self.symlinksCBox)

    # ...