Support defaults via Optional #52
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This will let Optional('foo', default=1) take precedence over simply `str` and thus have the opportunity to insert its default.
The only case for which this should change behavior is if somebody was comparing against a type with a `validate` attr. In that case, the logic would have gone down the wrong path anyway, attempting to call validate() on the type itself.
Then we don't have to filter them back out later.
Error trapping on Optional construction is to follow, split out for ease of review, since it will likely require some refactoring.
… single, static key.
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The reason the defaults are used verbatim, rather than being passed through any value validators, is that it's more convenient in my use cases to come up with a programmatic value than a raw representation. You can always get the opposite behavior by factoring out any validators in question and manually passing a raw value through them. Perhaps more compellingly, inverting the opposite behavior would not always be possible. |
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I believe this also fixes #23. |
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Thanks, Erik! |
keleshev
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Feb 27, 2015
Support defaults via Optional
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Thanks for the quick merge! :-D |
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This lets us insert default values for missing dict keys. I independently arrived at this API before seeing that it's also a leading contender in #19, so it's at least unsurprising for 2 people. :-)
I had to do a minor twiddle of prioritization so that more generic keys like
strwouldn't eat the Optionals' lunch, but that shouldn't affect any conceivable non-crashing use case. (See one of the commit messages for details.)