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POPython method that is also a generator function?
 

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  1. POPython method that is also a generator function?
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    <p>I'm trying to build a method that also acts like a generator function, at a flip of a switch (<code>want_gen</code> below).</p> <p>Something like:</p> <pre><code>def optimize(x, want_gen): # ... declaration and validation code for i in range(100): # estimate foo, bar, baz # ... some code here x = calculate_next_x(x, foo, bar, baz) if want_gen: yield x if not want_gen: return x </code></pre> <p>But of course this doesn't work -- Python apparently doesn't allow <code>yield</code> and <code>return</code> in the same method, even though they cannot be executed simultaneously. </p> <p>The code is quite involved, and refactoring the declaration and validation code doesn't make much sense (too many state variables -- I will end up with difficult-to-name helper routines of 7+ parameters, which is decidedly ugly). And of course, I'd like to avoid code duplication as much as possible.</p> <p>Is there some code pattern that would make sense here to achieve the behaviour I want?</p> <hr> <p>Why do I need that?</p> <p>I have a rather complicated and time-consuming optimization routine, and I'd like to get feedback about its current state during runtime (to display in e.g. GUI). The old behaviour needs to be there for backwards compatibility. Multithreading and messaging is too much work for too little additional benefit, especially when cross-platform operation is necessary.</p> <p><strong>Edit:</strong> Perhaps I should have mentioned that since each optimization step is rather lengthy (there are some numerical simulations involved as well), I'd like to be able to "step in" at a certain iteration and twiddle some parameters, or abort the whole business altogether. The generators seemed like a good idea, since I could launch another iteration at my discretion, fiddling in the meantime with some parameters.</p>
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    1. COIf you are making a new version anyway, just leave the old version the way it is (for backwards compatibility), and make the new way under a different name while telling everybody to use that from now on.. Adding an alternative route in such a function will just reduce the performance for those using the old way (which would be acceptable) but also those that use the new way.
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    2. CO@poke: Indeed, I am well aware of the reduced performance (which is an issue). But the difference between the two versions is so small (three lines or so), that it doesn't make sense to have two versions (the method is ~50 lines w/ whitespace long, and modifications and fine tunning are to be expected, preserving the behaviour).
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