First on why numbered captures are read-only. I'm not quite sure about the reason, but I think it's a performance issue. Captures aren't actually stored as copies, but as indexes into the string. This saves a lot of copying, and gives better performance.

But I'm sure about the second issue, why named captures behave the same as numbered captures when it comes to readonlyness. Named captures are stored the same way as numbered captures. The difference is that when the regexp is compiled perl makes a mapping from name to number. And then when you do $+{first} perl looks up first and sees it's mapped to 1, meaning that $+{first} is just another name for $1. This also means that if $1 is read only, so is $+{first}.

Now, I easily understand why numbered captures should be read only, since they may be clobbered by another regexp-like operator. But from the UI POV, IMHO (sic!) if you use named captures, then you have control enough to know better: if you do want to clobber them, then it's your business
That reasoning I don't understand. How does using named captures give you more control? If numbered captures can be clobbered, how come named captures don't?

In reply to Re: Why are 5.10's named captures read only? by JavaFan
in thread Why are 5.10's named captures read only? by blazar

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