String: add sub with index and range
#2823
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Well, exactly, why can't this be |
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Strings are immutable |
| private def range_to_index_and_size(range) | ||
| from = range.begin | ||
| from += size if from < 0 | ||
| raise IndexError.new if from < 0 |
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Proper error message already pretty please?
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Include the from in the message, something like #{from} out of bounds?
To be honest, I'm not sure these error messages are very useful. If you get IndexError you have a bug in your program. If you see "3 not in 0..2" you don't get a lot of information to fix the bug just from that info. You'll have to debug it anyway to understand why that 3 got there in the first place.
But I can add a message. What message?
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Perhaps it's not super useful but I think it's useful enough for a lot of cases, I often start to debug them by first printing the input values and boundaries, that step wouldn't be necessary then. But in general it also makes the language appear more friendly, at least it's trying to give as much information as possible, instead of throwing a blunt "wrong" into your face.
I started making all IndexErrors verbose but got stuck on #2819, you can see the message I used here: https://github.com/jhass/crystal/blob/better_index_error/src/exception.cr#L189-L198
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Merged in 7a9dfaf We can later improve the error messages |
In Ruby this is
String#[]=, which we were missing. Suggestions for alternatives to the namesubare accepted, but maybesubis good enough.