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POPython namespace elements visibility (vs proper package structure)
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copied!<p><strong>Python3</strong></p> <p>Tried to found an answer but failed. First I'll present the snippet, then I'll explain why I wanted to do it this way and what I wanted to achieve. Maybe it'll look like this approach is "the bad one". Hence this semi-double topic, cause first I'd like to know why this snippet isn't working and second - I'd like to know if this approach is right.</p> <p>So:</p> <pre><code>class Namespace: def some_function(): pass class SomeClass: fcnt = some_function </code></pre> <p>This won't work due to:</p> <p><code>NameError: name 'some_function' is not defined</code></p> <p>What I want to achieve is code and file structure readability. </p> <p>Above example is a snippet which I use (not this one, but it looks like this) in Pyramid project.</p> <p>My project tree looks like this:</p> <pre><code>my_project ├── models │ ├── __init__.py │ └── some_model.py ├── schemas │ ├── __init__.py │ ├── some_schema.py │ └── some_other_schema.py ... ├── views │ ├── __init__.py │ └── some_view.py └── __init__.py </code></pre> <p>What I wanted to achieve is clean schema/model/view importing. </p> <p>In <strong>some_schema.py</strong> file resides <code>class SomeSchema</code>, in <strong>some_other_schema.py</strong> <code>class SomeOtherSchema</code>.</p> <p>With above snippet I can make: <code>from my_project.schemas.some_schema import Schema</code></p> <p>and use it like <code>Schema.SomeSchema()</code></p> <p>I've got a little bit lost with packages and <code>import</code>s. How one could make a clean structure (one schema per file) and still be able to use Schema namespace? (In C++ I'd just put each of those classes in <code>Schema</code> namespace, that's why I did this in snippet above. But! What works in C++ maybe shouldn't be used in python, right?).</p> <p>Thanks for answer in advance.</p> <p><strong>EDIT:</strong> Ok, I've done some testing (I thought that I've done it, but looks like not..).</p> <ol> <li>using <code>from my_project.schemas.some_schema import Schema</code> with another <code>from my_project.schemas.some_other_schema import Schema</code> causes in the second import shadowing first one. So if after first import I'd be able to use <code>x = Schema.SomeSchema()</code> than after second import I'd be unable to do this, because <code>class Schema</code> gets overriden. Right, so as Erik said - classes aren't namespaces. GOT IT!</li> <li><p>in my very first snippet yes, I should've used <code>fnct = Namespace.some_function</code>. What's wierd - it works. I have the same statement in my pyramid code, with one difference. <code>some_function</code> has <code>@colander.deferred</code> decorator. In fact it looks like this:</p> <pre><code>class Schema: @colander.deferred def deferred_some_function(node, kw): something = kw.get("something", []) return deform.widget.SelectWidget(values=something, multiple=True) class SomeSchema(colander.MappingSchema): somethings = colander.SchemaNode(colander.Set(), widget=Schema.deferred_some_function) </code></pre> <p>And I get <code>NameError: name 'Schema' is not defined</code></p></li> <li><p>Getting back to package format. With this:</p> <pre><code>### another/file.py from foo.bar.schema import SomeSchema # do something with SomeSchema: smth = SomeSchema() smth.fcnt() </code></pre> <p>I have to make one module <code>foo/bar/schema.py</code> in which I'd have to put all my <code>SomeXSchema</code> classes. An if I have lots of them, then there's the unreadabilty glitch which I wanted to get rid off by splitting SomeXSchema - one per file. Can I accomplish this somehow? I want to call this class for example: <code>User</code>. And here's the THING. Maybe I do it wrong? I'd like to have class named <code>User</code> in <code>schema</code> <em>namespace</em> and class named <code>User</code> in <code>model</code> <em>namespace</em>. Shouldn't I? Maybe I ought to use prefix? Like <code>class SchemaUser</code> and <code>class ModelUser</code> ? I wanted to avoid it by the use of modules/packages. If I'd use : <code>import foo.bar.schema</code> then I'd have to use it like <code>x = foo.bar.schema.User()</code> right? There is no way to use it like <code>x = schema.User()</code> ? Sorry, I just got stuck, my brain got fixed. Maybe I need a little break to take a fresh look?</p> <p><strong>ANOTHER EDIT (FOR POINT 3 ONLY)</strong></p> <p>I did some more research. The answer here would be to make it like this:</p> <pre><code>## file: myproject/schemas/__init__.py from .some_schema import SomeSchema from .some_other_schema import SomeOtherSchema </code></pre> <p>then usage would be like this:</p> <pre><code>## some file using it import myproject.schemas as schema s1 = schema.SomeSchema() s2 = schema.SomeOtherSchema() </code></pre> <p>Would it be <em>lege artis</em>?</p></li> <li><p>If anyone thinks that topic should be changed - go ahead, give me something more meaningful, I'd appreciate it.</p></li> </ol>

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