[swift-evolution] Empower String type with regular expression

Patrick Gili gili.patrick.r at gili-labs.com
Sun Jan 31 15:46:42 CST 2016

Hi Dany,

Please find my response inline below.


> On Jan 31, 2016, at 3:46 PM, Dany St-Amant via swift-evolution <swift-evolution at swift.org> wrote:
> This seem to be two proposals in one:
> 1. Initialize NSRegularExpression with a single String which includes options
> The ultimate goal based on the earlier mail in the thread seems to be able in a future proposal do thing like: string ~= replacePattern, if string =~ pattern, decoupled from the legacy Obj-C. Isn’t NSRegularExpression part of the legacy? The conversion of the literal string as regular expression should probably part of the proposal for these operators; as this is the time we will know how we want the text to be interpreted.

I don't see any evidence of NSRegularExpression becoming part of any legacy. Given SE-005, SE-006, and SE-023, the name is probably changing from NSRegularExpression to RegularExpression. However, I don't think the definition of the class will change, only the name.

I would like to see an operator regular expression matching operator, like Ruby and Perl. I was trying to keep the proposal a minimal increment that would buy the biggest bang for the buck. We can already accomplish much of what other languages can do with regard to regular expression. However, the notion of a regular expression isn't something we can work around with custom library today. Can you suggest something addition that should be in the proposal?

> 2. Easily create a String without escaping (\n is not linefeed, but \ and n)
> The ability to not interpret the backslash as escape can be useful in other scenario that creating a NSRegularExpression; like creating a Windows pathname, or creating regular expression which are then given to external tool.  So this part of the proposal should probably be generalized.

Generalize it for what? If you're thinking along the line of raw strings, I agree that we need this capability, as well as multi-line string literals. However, I just soon we have separate proposals for this.

> Dany
>> Le 31 janv. 2016 à 12:18, Patrick Gili via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> a écrit :
>> Here is the link to the proposal on GitHub:
>> https://github.com/gili-patrick-r/swift-evolution/blob/master/proposals/NNNN-regular-expression-literals.md <https://github.com/gili-patrick-r/swift-evolution/blob/master/proposals/NNNN-regular-expression-literals.md>
>> Cheers,
>> -Patrick
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