Re^2: How do I change substitution options within a program?

See perlop, namely qr/PATTERN/options. With qr// you can change imosx options as you wish within dynamically generated patterns.

I read your comment as meaning you can set the regex options from variables when using qr//. However, none of the following work for me:

$mods = "im";

$test = qr/xyz/$mods;   # Syntax error.
$test = qr/xyz/"$mods"; # Ditto.
$test = qr/xyz/\$mods;  # Ditto.
                        # ... out of ideas.
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Could you clarify your post? What can you do with qr// and modifiers that you can't with m// or s///?

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Re^3: How do I change substitution options within a program? by ikegami (Patriarch) on Oct 31, 2006 at 23:41 UTC
Nothing. Maybe he was thinking of the following: `# XXX WRONG DON'T USE THIS $re = qr/$re/i if $opt{i}; $re = qr/$re/m if $opt{m}; $re = qr/$re/s if $opt{s}; $re = qr/$re/x if $opt{x};` [download] On the other hand, the following does work: `$re = "(?i:$re)" if $opt{i}; $re = "(?m:$re)" if $opt{m}; $re = "(?s:$re)" if $opt{s}; $re = "(?x:$re)" if $opt{x};` [download]	[reply] [d/l] [select]

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Re^3: How do I change substitution options within a program?
by ikegami (Patriarch) on Oct 31, 2006 at 23:41 UTC

Nothing. Maybe he was thinking of the following:

# XXX WRONG DON'T USE THIS
$re = qr/$re/i if $opt{i};
$re = qr/$re/m if $opt{m};
$re = qr/$re/s if $opt{s};
$re = qr/$re/x if $opt{x};
[download]

On the other hand, the following does work:

$re = "(?i:$re)" if $opt{i};
$re = "(?m:$re)" if $opt{m};
$re = "(?s:$re)" if $opt{s};
$re = "(?x:$re)" if $opt{x};
[download]

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