s///x
in [Perl]
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From: Dr.Ruud on 3 Nov 2005 05:04 Tad McClellan: > Dr.Ruud: >> Anno Siegel: >>> The changes by /x only affect the regex proper. The replacement >>> part is still an ordinary double-quotish string. >> >> OK. I am still trying to think up why it was chosen to not affect the >> replacement part. > > Because spaces are _supposed_ to matter when they are in a string. There can also be spaces in the regex, and there are several ways to present them. I use \s where possible, and also "\x{0020}", "\x{20}", even "[ ]", "\ ", depending on the context. So I still see no reason why unprotected spaces should not be ignored in the replacement part. "\x{20}" and "\ " would work fine there too. Or use a variable with a run of spaces, like $space42 = ' 'x42, and an o-modifier. -- Affijn, Ruud (gimme a \X) "Gewoon is een tijger."
From: Dr.Ruud on 3 Nov 2005 05:40 Anno Siegel: > Redundant constructs are an important indicator *against* the authors > competence. That's why it is generally a good idea to avoid them. I generally agree. The Posting Guidelines say: "Do not provide too much information", so I did cut down my code to an example of a few lines. But I forgot to toss the s-modifier. And now that I have inserted the m- and x-modifiers in all the appropriate places (I had read that chapter of PBP before but had forgot about it), I won't even have to do that anymore. :) -- Affijn, Ruud "Gewoon is een tijger."
From: Anno Siegel on 3 Nov 2005 09:13 Dr.Ruud <rvtol+news(a)isolution.nl> wrote in comp.lang.perl.misc: > "Gewoon is een tijger." "Habit is a tiger"? Yeah, a sleepy one, but when you want him to move he's got teeth. Anno -- If you want to post a followup via groups.google.com, don't use the broken "Reply" link at the bottom of the article. Click on "show options" at the top of the article, then click on the "Reply" at the bottom of the article headers.
From: Dr.Ruud on 3 Nov 2005 19:11 Abigail: > /o only matters if you have a variable inside regexp, and then > only > if you encounter the regex more than once with a different value in > the variable. And then only if you want to keep using the old value. I have series of substitutions that have to be tried in order on every line of many files. To make the code more readable, I can store these substitutions in a hash (with keys like 'A01' meaning phase A, first substitution). It is no problem to unloop the code for speed, so it might look like: $x = s/$re{'A01'}[SRCH]/$re{'A01')[REPL]/gsx; # or /gosx print STDERR $re{'A01'}[NAME], $x if ($x > $re{'A01'}[MIN]); $x = s/$re{'A02'}[SRCH]/$re{'A02')[REPL]/gsx; print STDERR $re{'A02'}[NAME], $x if ($x > $re{'A02'}[MIN]); (and then dozens more) If possible, I would like the modifiers to be in $re{'key'}[MODS]. (yes, this is all totally untested code yet) OK, let me first try and test the alternatives. I still have a few days. -- Affijn, Ruud "Gewoon is een tijger."
From: Abigail on 3 Nov 2005 20:05
Dr.Ruud (rvtol+news(a)isolution.nl) wrote on MMMMCDXLVIII September MCMXCIII in <URL:news:dkectf.1bg.1(a)news.isolution.nl>: -: Abigail: -: -: > /o only matters if you have a variable inside regexp, and then -: > only -: > if you encounter the regex more than once with a different value in -: > the variable. And then only if you want to keep using the old value. -: -: -: I have series of substitutions that have to be tried in order on every -: line of many files. -: -: To make the code more readable, I can store these substitutions in a -: hash (with keys like 'A01' meaning phase A, first substitution). -: -: It is no problem to unloop the code for speed, so it might look like: -: -: $x = s/$re{'A01'}[SRCH]/$re{'A01')[REPL]/gsx; # or /gosx -: print STDERR $re{'A01'}[NAME], $x if ($x > $re{'A01'}[MIN]); The question you should ask here is: does "$re{A01}[SRCH]" change? And if it does, do you want to keep using the *old* value? If the answer to both questions is yes, you could use /o (although I would use qr//). If latter question is answered with 'no', using /o will make that your program will produce the wrong results. If the first question is answered with 'no', then using /o doesn't matter. -: $x = s/$re{'A02'}[SRCH]/$re{'A02')[REPL]/gsx; -: print STDERR $re{'A02'}[NAME], $x if ($x > $re{'A02'}[MIN]); -: -: (and then dozens more) -: Suppose you have @lines containing all the lines you want to inspect, and @regexes with all the regexes (as strings), there is a gigantic difference between: for my $line (@lines) { for my $regex (@regexes) { $line =~ /$regex/ } } and for my $regex (@regexes) { for my $line (@lines) { $line =~ /$regex/ } } The first code snippet means that you will be doing scalar (@lines) * scalar (@regexes) regex compilations, while in the latter case, you only will be doing scalar (@regexes) compilations. (Except if you have only one regex, then you will be compiling only once, in both code snippets). -: If possible, I would like the modifiers to be in $re{'key'}[MODS]. -: (yes, this is all totally untested code yet) s/(?$re{key}[MODS])$re{key}[SRCH]/$re{key}[REPL]/ ought to do the trick. Abigail -- map{${+chr}=chr}map{$_=>$_^ord$"}$=+$]..3*$=/2; print "$J$u$s$t $a$n$o$t$h$e$r $P$e$r$l $H$a$c$k$e$r\n"; |