import problem

[Mohsen Pahlevanzadeh]

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
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'
###########################################
When i changed the my code to:
#################################################33
from ui.interface.interface import *
obj = ui.interface.interface.InterfaceCodes()
##############################################3

I get the :

#################################333
raceback (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()
NameError: name 'ui' is not defined
###############################
Also if i delete "ui.interface.interface" i get the :
########################3333
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 = InterfaceCodes()
NameError: name 'InterfaceCodes' is not defined
############################

You make mme happy if help me....
Yours,
Mohsen

 

[Steven D'Aprano]

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!

 

[Mohsen Pahlevanzadeh]

thank you, you gave me "how to get fish" instead of "fish", it's very
better.

 

[Mohsen Pahlevanzadeh]

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:



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!

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

 

[Mohsen Pahlevanzadeh]

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

 

[Dave Angel]

thank you, you gave me "how to get fish" instead of "fish", it's very
better.

I'd suggest you make a diagram showing each file and indicate what files
it imports by an arrow. If any arrows form a circle, you (may) have
recursive imports.

You should try to organize your code so you don't have any loops in the
above diagram. In reasonable designs, you can do that by factoring out
some of the code into new bubbles. But if you have too many bubbles
already, that just makes it harder to keep track of.

The recursion can sometimes be debugged more easily by eliminating the
"from xxx import *" forms., which really hides what things you get.
You'll only get those symbols already defined in the particular loop,
(which is generaly the ones defined before its import statment) and you
won't find out about the missing one till you try to use it later.

It can sometimes be mitigated by using from xxx import y1, y2 where you
explicitly define those things before the import statement.

However, both of these require you to have the imports somewhere NOT at
the top of the file. And that can cause other problems.

Best is to avoid any loops in the diagram.