Hi

I wanted to be able to mark lines with comments at a fixed column an came up with this one-liner solution.

Did I miss a more elegant solution?

|perl -pe 'substr $_, -1, 0, " "x(68-length$_) . "  #:$1" if /(^#|nextstate|var\d+)/;'

Explanation:

• -p loop over input and print $_ at the end of -e evalcode
• substr is inserting the text just before the newline (index -1, length 0)
• " " x (68 - length $_) fills in space till column 68
• "  #:$1" inserts the match at column 70
• if line $_ longer than 68 char, append the match after two spaces

example with column 50

$ perl -MO=Concise,-src tst_b_xref4.pl|perl -pe 'substr $_, -1, 0, " "
+x(48-length$_) . "  #:$1" if /(^#|nextstate|var\d+)/;'
tst_b_xref4.pl syntax OK
j  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
# 1: for (                                       #:#
2     <;> nextstate(main 3 tst_b_xref4.pl:1) v:{ ->3  #:nextstate
4     <1> preinc[t2] vK/1 ->5
-        <1> ex-rv2sv sKRM/1 ->4
3           <#> gvsv[*var1] s ->4                #:var1
[download]

Use case: Re^12: B::Xref buggy?

update

a bit shorter |perl -pe 'chomp, $_.=" "x(48-length$_) . "  #:$1\n" if /(^#|nextstate|var\d+)/;'

update

meh, I expected a printf solution to be shorter

|perl -pe 'chomp, printf ("%-48s  #:$1\n",$_), $_="" if /(^#|var|nextstate)/'

update

|perl -pe 'chomp, $_ = sprintf "%-48s  #:$1\n",$_ if /(^#|var|nextstate)/'

IMHO best solution so far. :)

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.