From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-06-18T06:26:06+09:00
Subject: Re: stubborn program using readline - Perl finally beaten

On Sat, 18 Jun 2005, Wybo Dekker wrote:

> On Sat, 18 Jun 2005, Ara.T.Howard wrote:
>
>> put another way - you want the program to ALWAYS read from EITHER a file or
>> stdin and you ALWAYS want to interactively (eg. from a tty) run commands after
>> reading the file - so why not just say that in the code?
>>
>> #
>> #  program which does the above
>> #
>> jib:~ > cat a.rb
>> require 'readline'
>> include Readline
>>
>> inpath = ARGV.shift
>> infile = inpath ? open(inpath) : STDIN
>>
>> # count lines in stdin (the mail message):
>> n=0; while infile.gets: n+=1 end
>> puts "#{n} lines"
>>
>> # always get commands interactively
>> STDIN.reopen '/dev/tty' unless STDIN.tty?
>> readline("type return to quit: ")
>> puts "quitting..."
>>
>> you could take other approaches with dup'ing and forking but this might work
>> for you.
>
> This did it!!
> The essential line is: STDIN.reopen '/dev/tty' unless STDIN.tty?
> and I would say that this should actually be done in Readline at the first
> call of readline.
> I rewrote my Perl program showlines:

i think it's a bit more complicated than that because then you could not do

   readline_program.rb < commands.txt

which would be bad.  i'd have to look into perl module to see what they do -
but i suspect it would also give some suprising behaviour under certain
conditions too... it's just too tough to imagine all the combinations of
tty/stdin one might want in a program...  but maybe not.

cheers.

-a
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