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Raku port of Perl's chomp() / chop() built-ins
use P5chomp; # exports chomp() and chop()
chomp $a;
chomp @a;
chomp %h;
chomp($a,$b);
chomp(); # bare chomp may be compilation error to prevent P5isms in Raku
chop $a;
chop @a;
chop %h;
chop($a,$b);
chop(); # bare chop may be compilation error to prevent P5isms in Raku
This module tries to mimic the behaviour of the Perl's chomp and chop built-ins in Raku as closely as possible.
chop VARIABLE
chop( LIST )
chop Chops off the last character of a string and returns the character
chopped. It is much more efficient than "s/.$//s" because it
neither scans nor copies the string. If VARIABLE is omitted, chops
$_. If VARIABLE is a hash, it chops the hash's values, but not its
keys, resetting the "each" iterator in the process.
You can actually chop anything that's an lvalue, including an
assignment.
If you chop a list, each element is chopped. Only the value of the
last "chop" is returned.
Note that "chop" returns the last character. To return all but the
last character, use "substr($string, 0, -1)".
chomp VARIABLE
chomp( LIST )
chomp This safer version of "chop" removes any trailing string that
corresponds to the current value of $/ (also known as
$INPUT_RECORD_SEPARATOR in the "English" module). It returns the
total number of characters removed from all its arguments. It's
often used to remove the newline from the end of an input record
when you're worried that the final record may be missing its
newline. When in paragraph mode ("$/ = """), it removes all
trailing newlines from the string. When in slurp mode ("$/ =
undef") or fixed-length record mode ($/ is a reference to an
integer or the like; see perlvar) chomp() won't remove anything.
If VARIABLE is omitted, it chomps $_. Example:
while (<>) {
chomp; # avoid \n on last field
@array = split(/:/);
# ...
}
If VARIABLE is a hash, it chomps the hash's values, but not its
keys, resetting the "each" iterator in the process.
You can actually chomp anything that's an lvalue, including an
assignment:
chomp($cwd = `pwd`);
chomp($answer = <STDIN>);
If you chomp a list, each element is chomped, and the total number
of characters removed is returned.
Note that parentheses are necessary when you're chomping anything
that is not a simple variable. This is because "chomp $cwd =
`pwd`;" is interpreted as "(chomp $cwd) = `pwd`;", rather than as
"chomp( $cwd = `pwd` )" which you might expect. Similarly, "chomp
$a, $b" is interpreted as "chomp($a), $b" rather than as
"chomp($a, $b)".
In future language versions of Raku, it will become impossible to access the $_ variable of the caller's scope, because it will not have been marked as a dynamic variable. So please consider changing:
chomp;
to either:
chomp($_);
or, using the subroutine as a method syntax, with the prefix . shortcut to use that scope's $_ as the invocant:
.&chomp;
Elizabeth Mattijsen [email protected]
Source can be located at: https://github.com/lizmat/P5chomp . Comments and Pull Requests are welcome.
Copyright 2018-2020 Elizabeth Mattijsen
Re-imagined from Perl as part of the CPAN Butterfly Plan.
This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.