New checker: comparison to empty string constant #1183
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@atodorov Thanks for the PR! I've got to think this one over a bit. I've definitely had code where I compare to empty string as shorthand for If we go forward with this one I'd like to see us turn it off by default. |
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@rowillia - others to think about are |
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@atodorov The In these cases where we don't know the type of |
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I agree with @rowillia that this might make sense only in some situations. I think this can become an extension, since we don't have full support for disabled checks (only checker classes). |
atodorov
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@PCManticore @rowillia refactored into an extension so that people can enable it if they so desire. (I certainly have a need for these checkers). Can you comment on the code/docs, etc so I can proceed with the other examples I've listed in the comment above? |
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| You can activate this checker by adding the line:: | ||
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| load-plugins=pylint.extensions.docparams |
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Probably you mean emptystring here?
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| def _is_constant_empty_str(node): | ||
| return isinstance(node, astroid.Const) and isinstance(node.value, str) and node.value == '' |
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You can drop the middle check, since the last one makes it redundant.
| __implements__ = (interfaces.IAstroidChecker,) | ||
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| # configuration section name | ||
| name = 'cmp-empty-str' |
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compare-to-empty-string? Longer, but more intuitive.
| error_detected = False | ||
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| # x ?? "" | ||
| if _is_constant_empty_str(op_1) and op_2 in ['!=', '==', 'is not', 'is']: |
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Let's reuse this list, move it into a separate variable.
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@atodorov In general, it looks good, apart of a couple of small nits. |
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@PCManticore should be good to go now. |
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Thank you @atodorov |
Detects things like
Note that in some cases this is what the author needs but my experience tells me most of the times empty string value doesn't have a special meaning.
Note2: this probably belongs to the ComparisonChecker in base.py. This checker however only supports binary comparisons so I will have to fix his limitation first. Let me know how would you like to proceed about that.