How to embed a Python interpreter in a PyQT widget
I want to be able to bring up an interactive python terminal from my python application. Some, but not all, variables in my program needs to be exposed to the interpreter.
Currently I use a sub-classed and modified QPlainTextEdit and route all "commands" there to eval or exec, and keep track of a separate namespace in a dict. However there got to be a more elegant and robust way! How?
Here is an example doing just what I want, but it is with IPython and pyGTK... http://ipython.scipy.org/moin/Cookbook/EmbeddingInGTK
Below is what I currently have. But there are so many corner cases that I probably missed some. It is very slow, try a large print loop... It got to be a simpler and less bug prone way, ...I hope!!
It is the def runCommand(self) function that is the key to understanding my problem. I ideally don't want to improve it, I rather want to replace its content with something simpler and smarter.
The functionality of the console.updateNamespace({'myVar1' : app, 'myVar2' : 1234}) statement in "main" is also important.
import sys, os
import traceback
from PyQt4 import QtCore
from PyQt4 import QtGui
class Console(QtGui.QPlainTextEdit):
def __init__(self, prompt='$> ', startup_message='', parent=None):
QtGui.QPlainTextEdit.__init__(self, parent)
self.prompt = prompt
self.history = []
self.namespace = {}
self.construct = []
self.setGeometry(50, 75, 600, 400)
self.setWordWrapMode(QtGui.QTextOption.WrapAnywhere)
self.setUndoRedoEnabled(False)
self.document().setDefaultFont(QtGui.QFont("monospace", 10, QtGui.QFont.Normal))
self.showMessage(startup_message)
def updateNamespace(self, namespace):
self.namespace.update(namespace)
def showMessage(self, message):
self.appendPlainText(message)
self.newPrompt()
def newPrompt(self):
if self.construct:
prompt = '.' * len(self.prompt)
else:
prompt = self.prompt
self.appendPlainText(prompt)
self.moveCursor(QtGui.QTextCursor.End)
def getCommand(self):
doc = self.document()
curr_line = unicode(doc.findBlockByLineNumber(doc.lineCount() - 1).text())
curr_line = curr_line.rstrip()
curr_line = curr_line[len(self.prompt):]
return curr_line
def setCommand(self, command):
if self.getCommand() == command:
return
self.moveCursor(QtGui.QTextCursor.End)
self.moveCursor(QtGui.QTextCursor.StartOfLine, QtGui.QTextCursor.KeepAnchor)
for i in range(len(self.prompt)):
self.moveCursor(QtGui.QTextCursor.Right, QtGui.QTextCursor.KeepAnchor)
self.textCursor().removeSelectedText()
self.textCursor().insertText(command)
self.moveCursor(QtGui.QTextCursor.End)
def getConstruct(self, command):
if self.construct:
prev_command = self.construct[-1]
self.construct.append(command)
if not prev_command and not command:
ret_val = '\n'.join(self.construct)
self.construct = []
return ret_val
else:
return ''
else:
if command and command[-1] == (':'):
self.construct.append(command)
return ''
else:
return command
def getHistory(self):
return self.history
def setHisory(self, history):
self.history = history
def addToHistory(self, command):
if command and (not self.history or self.history[-1] != command):
self.history.append(command)
self.history_index = len(self.history)
def getPrevHistoryEntry(self):
if self.history:
self.history_index = max(0, self.history_index - 1)
return self.history[self.history_index]
return ''
def getNextHistoryEntry(self):
if self.history:
hist_len = len(self.history)
self.history_index = min(hist_len, self.history_index + 1)
if self.history_index < hist_len:
return self.history[self.history_index]
return ''
def getCursorPosition(self):
return self.textCursor().columnNumber() - len(self.prompt)
def setCursorPosition(self, position):
self.moveCursor(QtGui.QTextCursor.StartOfLine)
for i in range(len(self.prompt) + position):
self.moveCursor(QtGui.QTextCursor.Right)
def runCommand(self):
command = self.getCommand()
self.addToHistory(command)
command = self.getConstruct(command)
if command:
tmp_stdout = sys.stdout
class stdoutProxy():
def __init__(self, write_func):
self.write_func = write_func
self.skip = False
def write(self, text):
if not self.skip:
stripped_text = text.rstrip('\n')
self.write_func(stripped_text)
QtCore.QCoreApplication.processEvents()
self.skip = not self.skip
sys.stdout = stdoutProxy(self.appendPlainText)
try:
try:
result = eval(command, self.namespace, self.namespace)
if result != None:
self.appendPlainText(repr(result))
except SyntaxError:
exec command in self.namespace
except SystemExit:
self.close()
except:
traceback_lines = traceback.format_exc().split('\n')
# Remove traceback mentioning this file, and a linebreak
for i in (3,2,1,-1):
traceback_lines.pop(i)
self.appendPlainText('\n'.join(traceback_lines))
sys.stdout = tmp_stdout
self.newPrompt()
def keyPressEvent(self, event):
if event.key() in (QtCore.Qt.Key_Enter, QtCore.Qt.Key_Return):
self.runCommand()
return
if event.key() == QtCore.Qt.Key_Home:
self.setCursorPosition(0)
return
if event.key() == QtCore.Qt.Key_PageUp:
return
elif event.key() in (QtCore.Qt.Key_Left, QtCore.Qt.Key_Backspace):
if self.getCursorPosition() == 0:
return
elif event.key() == QtCore.Qt.Key_Up:
self.setCommand(self.getPrevHistoryEntry())
return
elif event.key() == QtCore.Qt.Key_Down:
self.setCommand(self.getNextHistoryEntry())
return
elif event.key() == QtCore.Qt.Key_D and event.modifiers() == QtCore.Qt.ControlModifier:
self.close()
super(Console, self).keyPressEvent(event)
welcome_message = '''
---------------------------------------------------------------
Welcome to a primitive Python interpreter.
---------------------------------------------------------------
'''
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
console = Console(startup_message=welcome_message)
console.updateNamespace({'myVar1' : app, 'myVar2' : 1234})
console.show();
sys.exit(app.exec_())
Answer
Bit late I know, but I recommend the code.InteractiveConsole class: http://docs.python.org/py3k/library/code.html#code.InteractiveConsole