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41 lines
1.5 KiB
XML
41 lines
1.5 KiB
XML
<!DOCTYPE qhelp PUBLIC
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"-//Semmle//qhelp//EN"
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"qhelp.dtd">
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<qhelp>
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<overview>
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<p>A cyclic import is an <code>import</code> which imports another module
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and that module imports (possibly indirectly) the module which contains the
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<code>import</code> statement.
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If all imports in a cyclic import occur at module level, then a module will be
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imported when it is part way through its initialization. This may rest in
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surprising errors, as parts of the module being imported may not yet exist.
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</p>
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<p>In addition to the possible errors, cyclic imports indicate that two modules
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are circularly dependent. This means that the modules cannot be tested
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independently, and it makes it harder to understand the architecture of the system.
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</p>
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</overview>
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<recommendation>
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<p>The cycle may be broken by removing any one import. If only one function or
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method requires the import, then consider moving that to the other module and
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deleting the import. If the two modules are more intimately connected, then move
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the inter-dependent parts into a third module and have both the original modules
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import that.
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</p>
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</recommendation>
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<references>
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<li>Python Language Reference: <a href="http://docs.python.org/2/reference/simple_stmts.html#import">The import statement</a>.</li>
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<li>Python: <a href="http://docs.python.org/2/tutorial/modules.html">Modules</a>.</li>
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<li> Effbot: <a href="https://web.archive.org/web/20200917011425/https://effbot.org/zone/import-confusion.htm">Import Confusion</a>.</li>
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</references>
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</qhelp>
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