Perl5 -> Perl6: sprintf

I love sprintf. After the wow! string concatenation hype, I found myself a lot more comfortable in adopting sprintf and alike for string formatting. It looks a lot nicer and more readable to me. Of course, it has drawbacks, as a lot of variadic methods: you can miss a parameter or fail its type. However, once set up, it is a lot stable than string concatenation (and can be translated in an easier way). The above means that a lot of messaging in my Perl programs use sprintf to, and often I use the following piece of code in Perl 5:

 say sprintf "Inizio elaborazione modo %s (%s) su file di output [%s] %s limite",
            $current_mode,
           %available_modes{ $current_mode },
           $output,
           ( $limit.defined ? sprintf '%d righe', $limit  : 'SENZA' ) );

Despite the fact that the string is in italian, you can see how simple it is. In Perl 6 I can enhance the above using the object-oriented nature and the fact that sprintf is now a method of Str:

 say "Inizio elaborazione modo %s (%s) su file di output [%s] %s limite"\
 .sprintf( $current_mode,
           %available_modes{ $current_mode },
           $output,
           ( $limit.defined ?? '%d righe'.sprintf( $limit ) !! 'SENZA' ) );

I like this form the most because it is a little more imperative: you order to say something that is then formatted, and not to say-format something. Please note the use of the unquote operator to keep things on different lines. It is not mandatory in this case, but it can be a good habit for when Perl 6 requires it. Also note the different ternary operator based on ?? !!.

The article Perl5 -> Perl6: sprintf has been posted by Luca Ferrari on September 18, 2017

Tags: raku , perl , programming