Question

One thing I miss about ipython is it has a ? operator which diggs up the docs for a particular function.

I know ruby has a similar command line tool but it is extremely inconvenient to call it while I am in irb.

Does ruby/irb have anything similar?

Answer 1

Pry is a Ruby version of IPython, it supports the ? command to look up documentation on methods, but uses a slightly different syntax:

pry(main)> ? File.dirname

From: file.c in Ruby Core (C Method):
Number of lines: 6

visibility:  public
signature:  dirname()

Returns all components of the filename given in file_name
except the last one. The filename must be formed using forward
slashes (/'') regardless of the separator used on the
local file system.

   File.dirname("/home/gumby/work/ruby.rb")   #=> "/home/gumby/work"

You can also look up sourcecode with the $ command:

pry(main)> $ File.link

From: file.c in Ruby Core (C Method):
Number of lines: 14

static VALUE
rb_file_s_link(VALUE klass, VALUE from, VALUE to)
{
    rb_secure(2);
    FilePathValue(from);
    FilePathValue(to);
    from = rb_str_encode_ospath(from);
    to = rb_str_encode_ospath(to);

    if (link(StringValueCStr(from), StringValueCStr(to)) < 0) {
    sys_fail2(from, to);
    }
    return INT2FIX(0);
}

See http://pry.github.com for more information 🙂