[PyQt] QScintilla code-completion bizarre behavior

[Brian Kelley]

I have spent some time making an example code-completion application,  
mostly to educate myself.  This simple application

(1) reads a raw .api file,
(2) prepares the file for loading into a lexer
(3) finally loads it and creates a new QScintilla object using the  
prepared API and turns code-completion on.

Sadly, the code-completion didn't work.  It didn't work until the  
"finished" function that loads the prepared API raised an exception at  
the end, then code completion works!

If the exception is not raised, then code-completion doesn't work.

I'm using
Qt-4.4.0
PyQt 4.4.2
QScintilla-commercial-2.2

Here is the application:

# begin sample application #
from PyQt4.QtGui import *
from PyQt4.QtCore import *
from PyQt4.Qsci import *
import sys

# Examle API
TESTAPI= """Constant1
Constant2
unknownFunction(??)
knownFunction(name, directory)
knownFunction2(number,string)
module.function(??)
"""

class Main(QMainWindow):
     def __init__(self):
         QMainWindow.__init__(self, None)
         b = QPushButton("Start", self)
         b.connect(b, SIGNAL("clicked()"), self.start)

     def start(self):
         lexer =  self.lexer = QsciLexerPython()
         api = QsciAPIs(lexer)

         # write the API to a file
         self.api = api
         test = open('test.api','w')
         test.write(TESTAPI)
         test.close()

         # load the api into
         assert api.load("test.api")
         api.connect(api, SIGNAL("apiPreparationStarted()"),   
self.started)
         api.connect(api, SIGNAL("apiPreparationFinished()"),  
self.finished)

         # prepare the binary version of the API, suitable for loading
         api.prepare()

     def started(self):
         pass#QMessageBox.information(self, "Started", "Started")

     def finished(self):
         # save the api to a binary file
         self.api.savePrepared("test.prepared")

         # Shows how to use the prepared API inside Scintilla with a  
prettier
         #  Python Mode
         editor = self.editor = QsciScintilla()
         editor.show()
         lexer =  QsciLexerPython()
         api = QsciAPIs(lexer)

         # load the api into the lexer so code-completion should
         #  work
         assert api.loadPrepared("test.prepared")
         lexer.setAPIs(api)
         editor.setAutoCompletionSource(editor.AcsAPIs)
         editor.setAutoCompletionThreshold(3)
         editor.setLexer(lexer)

         # set up the editor the prettier Python editing
         editor.setIndentationsUseTabs(False)
         font = QFont()
         fm = QFontMetrics(font)
         editor.setIndentationWidth(4)
         editor.setTabWidth(4)
         editor.show()
         if sys.platform != "win32":
             editor.zoomIn(3)
         editor.setIndentationsUseTabs(False)
         editor.setIndentationWidth(4)
         editor.setTabWidth(4)
           # conventionnaly, margin 0 is for line numbers
         editor.setMarginWidth(0, fm.width( "00000" ) + 5)
         editor.setMarginLineNumbers(0, True)

         ## Edge Mode shows a red vetical bar at 80 chars
         editor.setEdgeMode(QsciScintilla.EdgeLine)
         editor.setEdgeColor(QColor("#FF0000"))

         ## Folding visual : we will use boxes
         editor.setFolding(QsciScintilla.BoxedTreeFoldStyle)

         ## Braces matching
         editor.setBraceMatching(QsciScintilla.SloppyBraceMatch)

         ## Editing line color
         editor.setCaretLineVisible(True)
         editor.setCaretLineBackgroundColor(QColor("#CDA869"))

         ## Margins colors
         # line numbers margin
         editor.setMarginsBackgroundColor(QColor("#333333"))
         editor.setMarginsForegroundColor(QColor("#CCCCCC"))

         # folding margin colors (foreground,background)
         editor.setFoldMarginColors(QColor("#99CC66"),QColor("#333300"))

         # uncommenting this exception causes code-completion not to  
work.
         raise Exception("Why does this exception make code-completion  
work?")


app = QApplication(sys.argv)
mw = Main()
mw.show()
app.exec_()