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Cyclic module dependencies and relative imports in Python

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Suppose we have two modules with cyclic dependencies: # a.py import b def f(): return b.y x = 42 # b.py import a def g(): return a.x y = 43 The two modules are in the directory pkg with an empty __init__.py . Importing pkg.a or pkg.b works fine, as explained in this answer . If I change the imports to relative imports from . import b I get an ImportError when trying to import one of the modules: >>> import pkg.a Traceback (most recent call last): File "<stdin>", line 1, in <module> File "pkg/a.py", line 1, in <module> from . import b File "pkg/b.py", line 1, in <module> from . import a

How to implement a cyclic UIScrollView?

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问题 How to implement a cyclic UIScrollView? That is to say, when you scroll to the very left item then the UIScrollView will show the very right one. Any help would be appreciate. 回答1: Sure, you need three views. At any given time you have a left view, a right view and a current view. This requires notification of each movement through the UIScrollViewDelegate. If you detect that you moved right, you free left, make left = current, current = right, and make a new right. If you detect that you

Cyclic dependency between header files

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问题 I\'m trying to implement a tree-like structure with two classes: Tree and Node . The problem is that from each class I want to call a function of the other class, so simple forward declarations are not enough. Let\'s see an example: Tree.h: #ifndef TREE_20100118 #define TREE_20100118 #include <vector> #include \"Node.h\" class Tree { int counter_; std::vector<Node> nodes_; public: Tree() : counter_(0) {} void start() { for (int i=0; i<3; ++i) { Node node(this, i); this->nodes_.push_back(node)

Cyclic module dependencies and relative imports in Python

阅读更多关于 Cyclic module dependencies and relative imports in Python

问题 Suppose we have two modules with cyclic dependencies: # a.py import b def f(): return b.y x = 42 # b.py import a def g(): return a.x y = 43 The two modules are in the directory pkg with an empty __init__.py . Importing pkg.a or pkg.b works fine, as explained in this answer. If I change the imports to relative imports from . import b I get an ImportError when trying to import one of the modules: >>> import pkg.a Traceback (most recent call last): File \"<stdin>\", line 1, in <module> File \

How to resolve cyclic dependency in Maven?

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问题 How can we resolve a Maven cyclic dependency? Suppose A is the parent project and B and C are child projects. If B is dependent on C and C is dependent on B, is there any way to resolve the cyclic dependency other than having a different project. 回答1: Maven does not allow cyclic dependencies between projects, because otherwise it is not clear which project to build first. So you need to get rid of this cycle. One solution is the one you already mentioned, to create another project. Another