Feature #749

String#indent, String#tabto, etc.

Added by Thomas Sawyer about 7 years ago. Updated almost 4 years ago.

Assignee:Yukihiro Matsumoto


There are few indention related String extensions I find myself frequently reusing. Ruby really has nothing built-in that addresses this, so I'd like to the following methods, or something like them, ultimately make it into Ruby core.

# Preserves relative tabbing.
# The first non-empty line ends up with n spaces before nonspace.
def tabto(n)
if self =~ / *\S/
indent(n - $1.length)

# Indent left or right by n spaces.
# (This used to be called #tab and aliased as #indent.)
def indent(n)
if n >= 0
gsub(//, ' ' * n)
gsub(/^ {0,#{-n}}/, "")

# Aligns each line n spaces.
def tab(n)
gsub(/^ */, ' ' * n)

# Provides a margin controlled string.
# x = %Q{
# | This
# | is
# | margin controlled!
# }.margin
def margin(n=0)
d = ((/\A.\n\s(.)/.match(self)) ||
return '' unless d
if n == 0
gsub(/\n\s*\Z/,'').gsub(/\s*[#{d}]/, '')
gsub(/\n\s*\Z/,'').gsub(/\s*[#{d}]/, ' ' * n)

These methods come in very handy in avoiding the need to shove HERE docs up against the left margin, or use repetitive string concatenations. I've seen others mention them from time to time as well, so I know I'm not the only one using them.

Of course, they'd need to be converted to C, but given the size and character of the definitions, I imagine it would be a fairly straight forward translation.

(Giving credit where it is due: The first three methods were originally written by Gavin Sinclair. The later method, if I recall correctly, by Peter Vanbroekhoven).


#1 Updated by Koichi Sasada about 7 years ago

  • Assignee set to Yukihiro Matsumoto



#2 Updated by Shyouhei Urabe about 5 years ago

  • Status changed from Open to Assigned



#3 Updated by Yusuke Endoh almost 4 years ago

  • Status changed from Assigned to Rejected

I'm rejecting this feature ticket because no progress has been made
for a long time. See [ruby-42391].

Sorry, I can say few comments. The use case is trivial for me.
There is nothing wrong with the proposal, I think. But matz did not
answer, and will not, just keeping this ticket open.
I suggest you, or those who want these features, to get a fresh start;
create a new ticket (with a patch if possible), and appeal to matz.

Yusuke Endoh mame@tsg.ne.jp

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