«

I have a variable which contains a text string. I want to print a
modified verion of the string without changing the variable. Consider
this code, which simply reverses each occurance of the word "gas":

my $word = 'gas';
my $string = "Jumping Jack Flash, It's a gas, gas, gas.";
(my $temp = $string) =~ s/$word/reverse $word/ieg;
print "$temp\n";

That works, but it uses an intermediate variable ($temp). I dislike
intermediate variables.

I could create a subroutine, but that's even uglier.

Is there an elegant way to print the modified version of the string
without an intermediate variable or a subroutine?

wrote:
> I have a variable which contains a text string. I want to print a
> modified verion of the string without changing the variable. Consider
> this code, which simply reverses each occurance of the word "gas":
>
> my $word = 'gas';
> my $string = "Jumping Jack Flash, It's a gas, gas, gas.";
> (my $temp = $string) =~ s/$word/reverse $word/ieg;
> print "$temp\n";
>
> That works, but it uses an intermediate variable ($temp). I dislike
> intermediate variables.
>
> I could create a subroutine, but that's even uglier.
>
> Is there an elegant way to print the modified version of the string
> without an intermediate variable or a subroutine?

Depending on your definition of elegant:

$ perl -le'
my $word = q/gas/;
my $string = "Jumping Jack Flash, It\047s a gas, gas, gas.";
print $string;
print map lc eq lc $word ? scalar reverse : $_, split /($word)/i, $string;
'
Jumping Jack Flash, It's a gas, gas, gas.
Jumping Jack Flash, It's a sag, sag, sag.



John
--
use Perl;
program
fulfillment

>John W. Krahn wrote:
>>> print map lc eq lc $word ? scalar reverse : $_, split /($word)/i, $string;

Clever. I didn't realize you could do something like "split /($word)/".
That's handy to know.

Thanks!

:

> I have a variable which contains a text string. I want to print a
> modified verion of the string without changing the variable. Consider
> this code, which simply reverses each occurance of the word "gas":
>
> my $word = 'gas';
> my $string = "Jumping Jack Flash, It's a gas, gas, gas.";
> (my $temp = $string) =~ s/$word/reverse $word/ieg;
> print "$temp\n";
>
> That works, but it uses an intermediate variable ($temp). I dislike
> intermediate variables.

How do you feel about using '$_'?

$_ = $string;
s/$word/reverse $word/ieg;
print $_, "\n";

--
Affijn, Ruud

"Gewoon is een tijger."

Dr.Ruud <rvtol+> wrote in comp.lang.perl.misc:
> :
>
> > I have a variable which contains a text string. I want to print a
> > modified verion of the string without changing the variable. Consider
> > this code, which simply reverses each occurance of the word "gas":
> >
> > my $word = 'gas';
> > my $string = "Jumping Jack Flash, It's a gas, gas, gas.";
> > (my $temp = $string) =~ s/$word/reverse $word/ieg;
> > print "$temp\n";
> >
> > That works, but it uses an intermediate variable ($temp). I dislike
> > intermediate variables.
>
> How do you feel about using '$_'?
>
> $_ = $string;
> s/$word/reverse $word/ieg;
> print $_, "\n";

Squeezing it in a one-liner:

print do { s/$word/reverse $word/ieg; $_ }, "\n" for "$string";

The quotes around the bare variable "$string" are needed to protect $string
from being changed in the process. Without them, $_ would be an alias for
$string and s/// would apply to it.

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
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"Reply" at the bottom of the article headers.

Anno Siegel:

> Squeezing it in a one-liner:
> print do { s/$word/reverse $word/ieg; $_ }, "\n" for "$string";


I had been playing with these:

print do {$_=$string; s/$word/reverse $word/ieg; $_}, "\n";


print eval($_=$string, s/$word/reverse $word/ieg, '$_'), "\n";

print ''.($_=$string, s/$word/reverse $word/ieg, $_)."\n";

print ''.($_=$string, s/$word/reverse $word/ieg)[0], "\n";

As you can see, I dont know how to stop 'print' to be a function.

--
Affijn, Ruud <http://www.pandora.com/?sc=sh770781&cmd=tunermini>

"Gewoon is een tijger."

Dr.Ruud <rvtol+> wrote:


> print eval($_=$string, s/$word/reverse $word/ieg, '$_'), "\n";
>
> print ''.($_=$string, s/$word/reverse $word/ieg, $_)."\n";
>
> print ''.($_=$string, s/$word/reverse $word/ieg)[0], "\n";
>
> As you can see, I dont know how to stop 'print' to be a function.


I think this post should clear it up:

Message-Id: <>


IOW, simply choose to put parenthesis around print's argument list
when you have a parenthesis following the function name.


--
Tad McClellan SGML consulting
Perl programming
Fort Worth, Texas

Tad McClellan:
> Dr.Ruud:

>> print ''.($_=$string, s/$word/reverse $word/ieg)[0], "\n";
>> As you can see, I dont know how to stop 'print' to be a function.
>
> I think this post should clear it up:
>
> Message-Id:

The Internet standard way to express such a pointer:

<news:>

(see RFC 3986)


> IOW, simply choose to put parenthesis around print's argument list
> when you have a parenthesis following the function name.

Yes, I even knew the FAQ, but I hadn't tried it yet. I had even tried
the "+" but couldn't get it to work.

perldoc -f print says: Also be
careful not to follow the print keyword with a left parenthesis
unless you want the corresponding right parenthesis to termi-
nate the arguments to the print--interpose a "+" or put paren-
theses around all the arguments.

OK, now I tried again. This gives the requested output:

print (($_=$string, s/$word/reverse $word/ieg)[0], "\n");

and this too:

print +($_=$string, s/$word/reverse $word/ieg)[0], "\n";

--
Affijn, Ruud <http://www.pandora.com/?sc=sh770781&cmd=tunermini>

"Gewoon is een tijger."

wrote:

> my $word = 'gas';
> my $string = "Jumping Jack Flash, It's a gas, gas, gas.";
> (my $temp = $string) =~ s/$word/reverse $word/ieg;
> print "$temp\n";

> I could create a subroutine, but that's even uglier.
>
> Is there an elegant way to print the modified version of the string
> without an intermediate variable or a subroutine?

That depends on what is you objection to a subroutine.

If you just want to your code to look smooth and you are not worrying
about the subroutine call overhead you could use List::MoreUtils::apply.

use List::MoreUtils qw(apply);
print ( (apply { s/$word/reverse $word/ieg } $string), "\n");