Conditional options to a regexp match?

[David Wake]

I want to do a case-insensitive regexp match if and only if the variable
$insensitive is set.

One way would be

if ($insensitive) {
/($pattern)/i;
}
else {
/($pattern)/;
}

Is there any way to do this with only one line of regexp searching?

I tried this:

my $searchoption = "";
$searchoption .= "i" if $insensitive;
/($pattern)/$searchoption;

but I get a syntax error.

Obviously, if we have three or four options the problem gets
exponentially bigger. For example, options for "i", "s" and "g" would
require eight possibilities. So it would be a big help if there is an
easy way to do this!

Thanks,

David

 

[Michael P. Broida]

I want to do a case-insensitive regexp match if and only if the variable
$insensitive is set.

One way would be

if ($insensitive) {
/($pattern)/i;
}
else {
/($pattern)/;
}

Is there any way to do this with only one line of regexp searching?

I tried this:

my $searchoption = "";
$searchoption .= "i" if $insensitive;
/($pattern)/$searchoption;

but I get a syntax error.

Obviously, if we have three or four options the problem gets
exponentially bigger. For example, options for "i", "s" and "g" would
require eight possibilities. So it would be a big help if there is an
easy way to do this!

Something with "eval"?? Something like:

$matchstatement = "\$x = m/(\$pattern)/"; # add escapes (\) as needed
if ($insensitive) $matchstatement .= "i"; # append desired options
if ($global) $matchstatement .= "g"; # ditto
...
eval $matchstatement; # I don't know the "eval" syntax

Don't know if that's "safe", but it seems like it
oughta work.

Mike

 

[John W. Krahn]

I want to do a case-insensitive regexp match if and only if the variable
$insensitive is set.

One way would be

if ($insensitive) {
/($pattern)/i;
}
else {
/($pattern)/;
}

Is there any way to do this with only one line of regexp searching?

I tried this:

my $searchoption = "";
$searchoption .= "i" if $insensitive;
/($pattern)/$searchoption;

but I get a syntax error.

Obviously, if we have three or four options the problem gets
exponentially bigger. For example, options for "i", "s" and "g" would
require eight possibilities. So it would be a big help if there is an
easy way to do this!

/(?@{[ $insensitive ? 'i' : '' ]}$pattern))/;



John

 

[Cognition Peon]

9:24pm, IP packets from John W. Krahn delivered:

/(?@{[ $insensitive ? 'i' : '' ]}$pattern))/;

Great solution. Thanks!! Never seen an example of
(?imsx) regular expression extension before.

 

[David Wake]

Something with "eval"?? Something like:

$matchstatement = "\$x = m/(\$pattern)/"; # add escapes (\) as needed
if ($insensitive) $matchstatement .= "i"; # append desired options
if ($global) $matchstatement .= "g"; # ditto
...
eval $matchstatement; # I don't know the "eval" syntax

Don't know if that's "safe", but it seems like it
oughta work.

Mike

"eval" was what I needed. Thanks!

David

 

[Anno Siegel]

9:24pm, IP packets from John W. Krahn delivered:

/(?@{[ $insensitive ? 'i' : '' ]}$pattern))/;

Great solution. Thanks!! Never seen an example of
(?imsx) regular expression extension before.

Look for the keyword "cloistered" in perlre for the whole story.

Anno

 

[Cognition Peon]

10:44pm, IP packets from Anno Siegel delivered:

9:24pm, IP packets from John W. Krahn delivered:

/(?@{[ $insensitive ? 'i' : '' ]}$pattern))/;

Great solution. Thanks!! Never seen an example of
(?imsx) regular expression extension before.

Look for the keyword "cloistered" in perlre for the whole story.

Now, I see the wonderful Monastery

 

[John W. Krahn]

9:24pm, IP packets from John W. Krahn delivered:

/(?@{[ $insensitive ? 'i' : '' ]}$pattern))/;

Great solution. Thanks!! Never seen an example of
(?imsx) regular expression extension before.

Actually it is an example of the (?imsx extension. Using the (?imsx)
extension it would be:

/(?@{[ $insensitive ? 'i' : '' ]})($pattern)/;



John