Using PythonTidy in pydev as code formatter.

My favorite python ide is Eclipse + Pydev. Pydev is a good eclipse plugin to make develop with python efficiently. But you will find its Autoformat (code format) feature is too simple to make things work.

I worked with some python newbie, they are just learning python and don’t know what is PEP08 (Style Guide for Python Code). Usually, they are experts in some other languages like C++, Java or C# with powerful IDE. They rely on code completion and code format feature too much. When they use Eclipse + Pydev, the source code they written is terrible…

I searched python code formatter (beautifier) for a long time. Unfortunately, there is no good product or tool to do that. Finally, the tool which is the closest to what I want is PythonTidy. This script format your code to fulfill PEP08 and it can be customized to satisfy the coding standard in your team.

The problem is PythonTidy is a standalone script to run it. This is not very convenient for us to use it. We must make pydev to integrated with PythonTidy to enhance its code format feature.

Basically, the pydev is a extensible tool to make us integrated PythonTidy easily. You can write some Jython script to extend pydev if you familiar with Java and Eclipse also. I wrote a simple script to make PythonTidy work while we press Ctrl+Shift+F.

If you want to use it, save the code below in somewhere you want as pyedit_pythontidy.py (pyedit_ is required).

"""
This code is public domain.
The original author is Bear Huang (https://bear330.wordpress.com/).
"""
if False:
    from org.python.pydev.editor import PyEdit #@UnresolvedImport
    cmd = 'command string'
    editor = PyEdit

assert cmd is not None
assert editor is not None

if cmd == 'onCreateActions':
    # from org.eclipse.jface.action import Action
    from org.python.pydev.editor.actions import PyAction
    from org.python.pydev.core.docutils import PySelection
    from java.lang import Runnable
    from org.eclipse.swt.widgets import Display
    from org.eclipse.jface.text import IDocument
    from org.eclipse.jface.text import TextSelection

    from java.io import FileWriter
    import java.lang.Exception

    FORMAT_ACTION_DEFINITION_ID = "org.python.pydev.editor.actions.pyFormatStd"
    FORMAT_ACTION_ID = "org.python.pydev.editor.actions.navigation.pyFormatStd"

    class PythonTidyAction(PyAction):

        def __init__(self, *args, **kws):
            PyAction.__init__(self, *args, **kws)

        def run(self):
            import tempfile
            import os

            try:
                ps = PySelection(editor)
                doc = ps.getDoc()
                startLine = ps.getStartLineIndex()

                p1 = tempfile.mktemp()
                p2 = tempfile.mktemp()
                f1 = FileWriter(p1)

                formatAll = False
                if ps.getTextSelection().getLength() == 0:
                    # format all.
                    c = doc.get()
                    f1.write(c)
                    formatAll = True
                else:
                    # format selection.
                    #c = ps.getSelectedText()
                    #f1.write(ps.getSelectedText())
                    print "Format selected text is not supported yet."
                    f1.write("")
                    # A kind of solution is to insert a special comment in
                    # front and end of selection text, pythontidy it, and
                    # extract text according that comment. 

                f1.close()
                os.system('PythonTidy.py "%s" "%s"' % (p1, p2))
                f2 = open(p2, "r")
                result = f2.read()
                f2.close()

                os.remove(p1)
                os.remove(p2)

                if startLine >= doc.getNumberOfLines():
                    startLine = doc.getNumberOfLines() - 1

                if formatAll:
                    doc.set(result)
                else:
                    #doc.replace(doc.getLineOffset(startLine), 0, result)
                    pass

                sel = TextSelection(doc, doc.getLineOffset(startLine), 0)
                self.getTextEditor().getSelectionProvider().setSelection(sel)
            except java.lang.Exception, e:
                self.beep(e)

    def bindInInterface():
        act = PythonTidyAction()

        act.setActionDefinitionId(FORMAT_ACTION_DEFINITION_ID)
        act.setId(FORMAT_ACTION_ID)
        try:
            editor.setAction(FORMAT_ACTION_ID, act)
        except:
            pass

    class RunInUi(Runnable):
        '''Helper class that implements a Runnable (just so that we
        can pass it to the Java side). It simply calls some callable.
        '''

        def __init__(self, c):
            self.callable = c
        def run(self):
            self.callable ()

    def runInUi(callable):
        '''
        @param callable: the callable that will be run in the UI
        '''
        Display.getDefault().asyncExec(RunInUi(callable))

    runInUi(bindInInterface)

Next, go to eclipse pydev preferences page to specify the script location:

Now, you can simply press Ctrl+Shift+F while edit python code.

(Format selected text is not supported yet, this is because I am too lazy to implement it in this time. If I have time and wish to do that, I will publish it as soon as posible.)

Any contributions are appreciated. 🙂