Re: Idiomatic Perl?

I see two things in that code that I would suggest to improve:

Don't use eval - it allows execution of arbitrary Perl code, and getting the quoting of interpolated code right is tricky (try entering one double quote for $str), and so it should only be used sparingly. In this case it is not needed, just say: my $answer = $str =~ /$pattern/; - however note that then, your regexes should not be entered with the surrounding slashes.
(If you do use eval someday, make sure to do proper error checking, as described e.g. here: something like eval "$code; 1" or warn "eval failed: $@";)
my $str = <STDIN>; and $pattern will have a newline on the end, which you should chomp off, e.g. chomp( my $str = <STDIN> );. See also the Basic debugging checklist, which suggests using a module like Data::Dumper or Data::Dump to look at what variables actually contain. If you use the former, I recommend setting $Data::Dumper::Useqq=1;.

In Perl, as opposed to Python's "there should be one - and preferably only one - obvious way to do it", TIMTOWTDI - There Is More Than One Way To Do It. While there are certainly 20 different ways to write the code you showed, don't worry about that too much - just keep your eye out for best practices like the ones I mentioned above, and otherwise enjoy learning Perl :-) We'll be happy to help.

Made a few minor edits.

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Re^2: Idiomatic Perl? by thenextfart (Novice) on Mar 20, 2018 at 14:26 UTC
Is it okay to just do `my $str = chomp(<STDIN>);`?	[reply] [d/l]
Re^3: Idiomatic Perl? by haukex (Archbishop) on Mar 20, 2018 at 14:46 UTC
Is it okay to just do `my $str = chomp(<STDIN>);?` No, because chomp is a bit special: it modifies its argument(s) and returns the total number of characters removed from all its arguments. The code you showed would fail because `chomp` wants to modify its arguments, but can't modify `<STDIN>` itself. The reason `chomp( my $str = <STDIN> );` works is because a scalar assignment in Perl like `( my $str = <STDIN> )` is modifiable (an "lvalue"), as described in Assignment Operators: "Modifying an assignment is equivalent to doing the assignment and then modifying the variable that was assigned to." If you want to be a little bit more verbose, what you can do is: `my $str = <STDIN>; chomp($str);` [download]	[reply] [d/l] [select]
Re^4: Idiomatic Perl? by Anonymous Monk on Mar 20, 2018 at 19:10 UTC
Extra parens arent idiomatic :p `chomp $foo;`	[reply] [d/l]
Re^3: Idiomatic Perl? by 1nickt (Canon) on Mar 20, 2018 at 14:30 UTC
Try it! What does it return? If it's not what you want, another approach might be to call the `chomp` on the result of the assignment: `chomp( my $str = <STDIN> );` [download] Hope this helps! The way forward always starts with a minimal test.	[reply] [d/l] [select]
Re^3: Idiomatic Perl? by Corion (Patriarch) on Mar 20, 2018 at 14:47 UTC
Depends on what you want to have in `$str`. Read chomp to learn about the return value of `chomp`.	[reply] [d/l] [select]
Re^4: Idiomatic Perl? by choroba (Cardinal) on Mar 20, 2018 at 15:03 UTC
`perl -we 'chomp <>'` [download] > Can't modify <HANDLE> in chomp at -e line 1, at EOF ($q=q:Sq=~/;[c](.)(.)/;chr(-\|\|-\|5+lengthSq)`"S\|oS2"`map{chr \|+ord }map{substrSq`S_+\|`\|}3E\|-\|`7**2-3:)=~y+S\|`+$1,++print+eval$q,q,a, [download]	[reply] [d/l] [select]