Re: What is the best way to compare variables so that different types are non-equal?

qr/STRING/msixpo
This operator quotes (and possibly compiles) its STRING as a regular expression. STRING is interpolated the same way as PATTERN in m/PATTERN/. If "'" is used as the delimiter, no interpolation is done. Returns a Perl value which may be used instead of the corresponding /STRING/msixpo expression. The returned value is a normalized version of the original pattern. It magically differs from a string containing the same characters: ref(qr/x/) returns "Regexp", even though dereferencing the result returns undef.

I think the relevant part of the docs is the bit I've highlighted. qr// ~~compiles~~ normalises the regex--which basically means blessing it. Hence the magical behaviour.

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Re^2: What is the best way to compare variables so that different types are non-equal? by ikegami (Patriarch) on Jul 19, 2009 at 16:10 UTC
I don't know why you crossed out "compiles". `>perl -Mre=debug -e"qr/a/" Compiling REx "a" Final program: 1: EXACT <a> (3) 3: END (0) anchored "a" at 0 (checking anchored isall) minlen 1 Freeing REx: "a"` [download]	[reply] [d/l]
Re^3: What is the best way to compare variables so that different types are non-equal? by BrowserUk (Patriarch) on Jul 19, 2009 at 16:21 UTC
I don't know why you crossed out "compiles". Because the docs I quoted used the term 'normalises'. Can they be both compiled and normalised? Can they be normalised and not compiled or vice versa? Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. RIP PCW	[reply]
Re^4: What is the best way to compare variables so that different types are non-equal? by ikegami (Patriarch) on Jul 19, 2009 at 16:25 UTC
Can they be both compiled and normalised? Yes. I didn't mean to imply what you said was wrong. Can they be normalised and not compiled or vice versa? No. `qr//` always compiles. `qr//` always returns the regex flags when used as as string.	[reply] [d/l] [select]


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