[ruby-talk:00383] FromJapan: #1

Hi folks!

Today, I pick up 11 topics -- 1 contrib and 10 Q&As. 

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	Contributions
	-------------

	[ruby-list:14713] ruby/gtk 0.18

	Kand-san put ruby-gtk-0.18.tar.gz into contrib. 
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	Q and A
	-------

	[ruby-list:14481] count lines
	
	Question:
		Would you tell me simple way to count number of lines
		in a file?
		And why does "foo\n\n\n".split(/\n/).size returns zero?

	Answer:
		Probably the fastest way may be:

open("afile").read.delete("\n").size

		Note that the above code does not count the last line
		if `afile' is not ended by "\n". 

		And "\n\n\n".split(/\n/, -1).size returns four. See the 
		reference manual. 
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	[ruby-list:14477] tiny ruby

	Question:
		I'm planning to archive ruby for PocketBSD, which is 
		customized FreeBSD for NEC's handheld machine Mobil Gear. 
		Is this plan is permitted?
		What is recommended in term of the license?

	Answer:
		Yes, permitted.  Give a distinct name to the package if you
		divert source code of ruby to different product. 
		It is written README. Please read REAME again. 
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	[ruby-list:14513] Hater

	Question:
		A pal hates ruby.  I'm so blue that I don't wanna go to
		school. Could you give me any advice?

	Reaction:
		A hundred answers are replied! I pick up impressive massages.

		* You are enviable. In my school days, none talk about 
		  what a programming language should be. 
		* The value of ruby doesn't depend on his liking. 
		* Don't be so serious. I dislike Perl, but I shall never 
		  hate a man by reason of he's loving Perl. 
		* No language satisfies all requests. 
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	[ruby-list:14521] Ruby style?

	Question:
		I'd like to write ruby ruby code.  Would you correct my 
		program?

#!/usr/local/bin/ruby

#  analyze command line argument
column=[]
column = ARGV.dup

in_file = column[0]    #  file name
num = column[1]        #  number of space

#  create output filename as input filename + .out
out_file = in_file + ".out"
print in_file,"--->",out_file,"\n"

#  open both infile and outfile
fin = open(in_file,"r")
fout = open(out_file,"w")

#  string to replace
space=" " * num.to_i

#  for each line of infile, replace and write
while fin.gets
  sub(/\r\n/,"\n")
  #  replace TAB to space
  gsub(/\t/,space)
  printf(fout,"%s",$_)
end

#  close files
fout.close
fin.close


	Answer:
		I would write as follows: 

--- tab2space.rb ---
#!/usr/bin/env ruby

require 'getopts'
getopts(nil, "n:")

tabwidth = $OPT_n ? $OPT_n.to_i : 8

while gets
  while sub!(/\t/) { " " * (tabwidth - $~.begin(0) % tabwidth) }
  end
  print
end
---

$ ruby -i.bak tab2space -n 4 foo.c

		Uniformly replace with fixed number of space makes indent 
		uneven, so number of space is roughly caliculated. 

		The above is for Ruby 1.3.x. Use the below for 1.2.x. 

while pos = $_.index(?\t)
  $_[pos] = " " * (tabwidth - pos % tabwidth)
end
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	[ruby-list:14525] Re: ruby style?

	Question:
		What does `#!/usr/bin/env ruby' cause?

	Answer:
		`ruby' will be invoked as so long as PATH includes the 
		directory on which ruby exits, with the proviso `env'
		must be on /usr/bin/.
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	[ruby-list:14525] Re: ruby style?

	Comment:

#!/usr/bin/ruby -i.back

		works but

#!/usr/bin/env ruby -i.back


	Comment:

#!/usr/bin/env ruby

$-i = ".back"


	Comment:
		I heard `#!' line allows `one command' and `at most one 
		option' in a shell script. 


	Comment:
		To avoid that limitation, The following is useful. 

#!/bin/sh 

# shell script around here

exec ruby -i.bbb -x $0 $*

Here anything skiped! 
You can write anything freely!

#! ruby
# ruby script starts heare
p $-i
p $0
p $*
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	[ruby-list:14586] Ruby, hardware description language

	Comment:
		I found a language Ruby, which is for circuit description. 
		http://www.comlab.ox.ac.uk/oucl/users/geraint.jones/ruby/
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	[ruby-list:14597] TkAfter munched memory.

	Question:
		I heard TkAfter is better than Tk.after because the latter
		costs for each registrating of proc. But the following 
		munches memories. 
require "tk"

TkAfter .new(10, -1, proc{p 'xxx'}) .start
Tk.mainloop

	Answer:
		It is bug of tcltklib.  I fixed it. Thank you for the report. 

		By the way, TkAfter is hardly used since thread provides same
		functions. 
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	[ruby-dev:6953] RString#len

	Comment:
		struct RString's member len is declared as int. It should
		be a integer type whose size as same as a pointer. 

	Answer:
		Once it had been size_t but it was not suitable because
		an index for string in ruby sometimes is valued negative 
		number. 

		On the other hand, ruby doesn't work on such that
		sizeof(long) != sizeof(void*). 
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	[ruby-dev:6992] ruby lacks some features of tr in Perl

	Comment:
		* String#tr cannot substitute "\0" but Perl's tr can.
		* String#delete doesn't support like a Perl's tr///d.

% perl -le '$_ = "123456789"; tr/2-8/4-6/d; print'
14569

	Answer:
		The former is bug. It has been fixed. 
		The latter will be supported as optional arguments and
		String#squeeze will be too in the later version. 
		It is planded that all arguments are logically conjuncted. 
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-- gotoken