Re: More questions on the "-pe" one-liner flag: in conjunction withs/// and tr///

Hi William,

I guess that you now have answers to your questions. I would suggest,
however, that you take a look as Andrew Shitov's book *Raku One-Liners*,
available on-line (
https://andrewshitov.com/wp-content/uploads/2020/01/Raku-One-Liners.pdf).

There are (around page 12) some explanations on your original question.

Consider especially the following equivalent one-liner programs:

$ raku-npe'.=flip' data.txt

and

$ raku-ne'.flip.say' data.txt

and the related explanations.

Cheers,
Laurent.




Le jeu. 7 mai 2020 à 10:12, Gianni Ceccarelli <dakkar@thenautilus.net> a
écrit :

> On 2020-05-06 William Michels via perl6-users <perl6-users@perl.org>
> wrote:
> > Are there any other "operators that modify their operands" in
> > Raku/Perl6 that don't require an initializing "." (dot)?
>
> The dot is used to call a method on an object.
>
> > I checked the "subst" command and it requires an initial ".=" when
> > used with the "-pe" one-liner flag:
>
> ``subst`` is a method https://docs.raku.org/type/Str#method_subst
>
> To summarise:
>
> * ``-e`` tells raku "execute the next argument as a program"
>
> * both the ``-p`` and ``-n`` command-line switches wrap the program in
>   a loop like::
>
>     for $*ARGFILES.lines -> {
>
>     }
>
>   ``-p`` additionally puts a ``say $_`` at the end of the block
>
> * inside that loop, the variable ``$_`` will have its value set to
>   each line of the input, one at a time
>
> * you can do whatever you want inside the loop
>
> * the dot calls a method, and if you don't specify an object to call
>   the method on (on the left hand side of the dot), ``$_`` is used
>
> * some operators (like ``s///`` or ``tr///``) operate on ``$_`` unless
>   told otherwise
>
> * assignment (``=``) can be combined with other operators (``+=``,
>   ``/=``, ``.=``, ``~=``, &c)
>
> If, having seen all that, the behaviour of all your examples is still
> not clear, maybe you should start writing your programs without
> shortcuts and implicit terms: the languages in the Perl family are
> very good at letting you write compact code, but sometimes this comes
> at the expense of clarity. While learning, code that's clear,
> explicit, and straightforward is often more helpful.
>
> --
>         Dakkar - <Mobilis in mobile>
>         GPG public key fingerprint = A071 E618 DD2C 5901 9574
>                                      6FE2 40EA 9883 7519 3F88
>                             key id = 0x75193F88
>

• More questions on the "-pe" one-liner flag: in conjunction with s///and tr/// by William Michels via perl6-users
• Re: More questions on the "-pe" one-liner flag: in conjunction withs/// and tr/// by Laurent Rosenfeld via perl6-users
• Re: More questions on the "-pe" one-liner flag: in conjunction withs/// and tr/// by William Michels via perl6-users
• Re: More questions on the "-pe" one-liner flag: in conjunction withs/// and tr/// by Gianni Ceccarelli
• Re: More questions on the "-pe" one-liner flag: in conjunction withs/// and tr/// by Laurent Rosenfeld via perl6-users
• Re: More questions on the "-pe" one-liner flag: in conjunction withs/// and tr/// by Gianni Ceccarelli