import problem
Mohsen Pahlevanzadeh
mohsen at pahlevanzadeh.org
Mon Sep 16 02:56:57 EDT 2013
On Mon, 2013-09-16 at 11:14 +0430, Mohsen Pahlevanzadeh wrote:
> On Mon, 2013-09-16 at 02:56 +0000, Steven D'Aprano wrote:
> > On Mon, 16 Sep 2013 06:53:26 +0430, Mohsen Pahlevanzadeh wrote:
> >
> > > Dear all,
> > >
> > > i have the following two line codes:
> > > ############################
> > > import ui.interface.interface
> > > obj = ui.interface.interface.InterfaceCodes()
> > > ###########################333
> > > I have same code in another package and work fine. but i get the :
> > >
> > > #####################################################3
> >
> > This traceback following suggests that your package is a complete tangled
> > mess of wild card imports. Perhaps I am misreading something, but the
> > following suggests that your package is highly coupled, with strong
> > dependencies between different modules. This is a poor design and will
> > give you many, many problems. As you are already having.
> >
> > Do you understand what I mean when I talk about modules being "highly
> > coupled"?
> >
> > Are you a Java or C++ developer learning Python? Your code suggests to me
> > that you might be. If you are, you should read these to get some ideas of
> > how your Java intuitions will lead you astray in Python:
> >
> > http://dirtsimple.org/2004/12/python-is-not-java.html
> > http://dirtsimple.org/2004/12/java-is-not-python-either.html
> >
> >
> > I assume that everything under the "amlak" directory is your code. Is
> > that correct?
> >
> > Here's the traceback again:
> >
> > > Traceback (most
> > > recent call last):
> > > File "./main.py", line 31, in <module>
> > > from materials.materials import *
> > > File "/home/mohsen/codes/amlak/amlak/src/materials/materials.py", line
> > > 40, in <module>
> > > from ui.interface.interface import *
> > > File "/home/mohsen/codes/amlak/amlak/src/ui/interface/interface.py",
> > > line 32, in <module>
> > > from ui.materialsFrame import *
> > > File "/home/mohsen/codes/amlak/amlak/src/ui/materialsFrame.py", line
> > > 24, in <module>
> > > from ui.materialsFindFrame import *
> > > File "/home/mohsen/codes/amlak/amlak/src/ui/materialsFindFrame.py",
> > > line 14, in <module>
> > > from common.objects.objects import *
> > > File "/home/mohsen/codes/amlak/amlak/src/common/objects/objects.py",
> > > line 28, in <module>
> > > obj = ui.interface.interface.InterfaceCodes()
> > > AttributeError: 'module' object has no attribute 'interface'
> > > ###########################################
> >
> >
> > So your main module does a wild-card import from materials.materials,
> > which does a wild-card import from ui.interface.interface, which does a
> > wild-card import from ui.materialsFrame, which does a wild-card import
> > from ui.materialsFindFrame, which does a wild-card import from
> > common.objects.objects, which requires ui.interface.interface to have
> > already been loaded and imported. But it hasn't been, because it is still
> > being imported.
> >
> > The *immediate* problem is that, in effect, before you can import
> > ui.interface.interface, you need to import ui.interface.interface.
> > Obviously this is going to cause you problems. Google on "recursive
> > imports" to learn about the sorts of problems and how to avoid them.
> >
> > The second problem is that, in general, you should try to avoid wild-card
> > imports. They're not always bad, but they were really invented for use in
> > the interactive interpreter so you can do things like this:
> >
> > from math import *
> > sqrt(42)
> > sin(1.5)
> >
> >
> > Using them inside non-interactive code is not forbidden exactly, but it
> > is frowned upon since it makes understanding your code harder.
> >
> > The third problem is that your code layout looks like you are fighting
> > Python, trying to force it to be something it is not. For starters, if
> > you're writing packages that look like this:
> >
> > ui.interface.interface
> >
> > that's simply poor design for Python. My guess is that you might be
> > following the Java convention of putting exactly one class per source
> > file. That is not the way Python code should be written. Modules should
> > contain all the related classes and functions, at least up to the point
> > that the module becomes so large that it is painful to work with. How
> > large is that? In my opinion, this is getting close to the maximum I
> > personally would be comfortable with:
> >
> > http://hg.python.org/cpython/file/3.3/Lib/decimal.py
> >
> >
> > although some people might be happy with large files.
> >
> > But what is important is that related code should be together in the one
> > file, not split across multiple modules and multiple packages.
> >
> > If you are trying to "future proof" your code, and thinking "today it is
> > small, but one day it will be big and will need to be a package with
> > dozens of modules", that doesn't matter. Don't write the code you think
> > you will need in five years. Write the code you need now. Google "YAGNI"
> > for more.
> >
> > I am sorry that I cannot just give you a simple one-line fix for your
> > error. As far as I can see, the fix is to re-design the package so that
> > it is flatter, with fewer imports, and avoid the recursive import.
> >
> > Good luck!
> >
> >
> >
> > --
> > Steven
> Dear Steven,
>
> I moved all of files to root of source directory, And create an put my
> constructor to objects.py file :
> #################################
> interfaceCodesObj = interface.InterfaceCodes()
> #############################333
> And in another files that i import object such as:
> ######################
> from objects import *
> ######################
> i get the the folloiwing traceback:
> ####################################3
> Traceback (most recent call last):
> File "/home/mohsen/codes/amlak/amlak/src/materialsFindFrame.py", line
> 187, in <lambda>
> QtCore.QObject.connect(self.checkBox,
> QtCore.SIGNAL(_fromUtf8("toggled(bool)")), lambda:
> interfaceCodesObj.unSetFilterDict("name"))
> NameError: global name 'interfaceCodesObj' is not defined
> Traceback (most recent call last):
> File "/home/mohsen/codes/amlak/amlak/src/materialsFindFrame.py", line
> 192, in <lambda>
> QtCore.QObject.connect(self.checkBox,
> QtCore.SIGNAL(_fromUtf8("toggled(bool)")), lambda:
> interfaceCodesObj.setFilterDict(self,self.checkBox,"name",self.lineEdit.text()))
> NameError: global name 'interfaceCodesObj' is not defined
> Traceback (most recent call last):
> File "/home/mohsen/codes/amlak/amlak/src/materialsFindFrame.py", line
> 198, in <lambda>
> QtCore.QObject.connect(self.checkBox,
> QtCore.SIGNAL(_fromUtf8("toggled(bool)")), lambda:
> interfaceCodesObj.responseToRequestForData(self))
> NameError: global name 'interfaceCodesObj' is not defined
> #######################################################
>
> I'm forced to used wildcard such as from~import syntax.
> you said correctly, i was C++ developer.
>
> Yours,
> Mohsen
>
I solved with alias :
import foo as bar
More information about the Python-list
mailing list