From: femto Zheng <femtowin@...>
Date: 2010-12-15T17:07:15+09:00
Subject: How do I define virtual global variable in ruby?

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Hello all,
in ruby c source code, there is
<http://codesearch.google.com/codesearch/p?hl=en#kOEgDIzD-Ao/trunk/lib/ruby/re.c&q=define_virtual&sa=N&cd=1&ct=rc&l=3369>rb_define_virtual_variable
like
rb_*define_virtual*_variable("$~", match_getter,
match_setter);<http://codesearch.google.com/codesearch/p?hl=en#kOEgDIzD-Ao/trunk/lib/ruby/re.c&q=define_virtual&sa=N&cd=1&ct=rc&l=3369>

  3370:     rb_*define_virtual*_variable("$&", last_match_getter, 0);
<http://codesearch.google.com/codesearch/p?hl=en#kOEgDIzD-Ao/trunk/lib/ruby/re.c&q=define_virtual&sa=N&cd=1&ct=rc&l=3370>
 3371:     rb_*define_virtual*_variable("$`", prematch_getter, 0);
<http://codesearch.google.com/codesearch/p?hl=en#kOEgDIzD-Ao/trunk/lib/ruby/re.c&q=define_virtual&sa=N&cd=1&ct=rc&l=3371>
 3372:     rb_*define_virtual*_variable("$'", postmatch_getter, 0);
<http://codesearch.google.com/codesearch/p?hl=en#kOEgDIzD-Ao/trunk/lib/ruby/re.c&q=define_virtual&sa=N&cd=1&ct=rc&l=3372>
 3373:     rb_*define_virtual*_variable("$+", last_paren_match_getter,
0); <http://codesearch.google.com/codesearch/p?hl=en#kOEgDIzD-Ao/trunk/lib/ruby/re.c&q=define_virtual&sa=N&cd=1&ct=rc&l=3373>
 3374:  <http://codesearch.google.com/codesearch/p?hl=en#kOEgDIzD-Ao/trunk/lib/ruby/re.c&q=define_virtual&sa=N&cd=1&ct=rc&l=3374>
 3375:     rb_*define_virtual*_variable("$=", ignorecase_getter,
ignorecase_setter);
<http://codesearch.google.com/codesearch/p?hl=en#kOEgDIzD-Ao/trunk/lib/ruby/re.c&q=define_virtual&sa=N&cd=1&ct=rc&l=3375>
 3376:     rb_*define_virtual*_variable("$KCODE", kcode_getter,
kcode_setter); <http://codesearch.google.com/codesearch/p?hl=en#kOEgDIzD-Ao/trunk/lib/ruby/re.c&q=define_virtual&sa=N&cd=1&ct=rc&l=3376>
 3377:     rb_*define_virtual*_variable("$-K", kcode_getter,
kcode_setter); <http://codesearch.google.com/codesearch/p?hl=en#kOEgDIzD-Ao/trunk/lib/ruby/re.c&q=define_virtual&sa=N&cd=1&ct=rc&l=3377>
 3378:  <http://codesearch.google.com/codesearch/p?hl=en#kOEgDIzD-Ao/trunk/lib/ruby/re.c&q=define_virtual&sa=N&cd=1&ct=rc&l=3378>

so actually this looks like global variable, but when you get/set it,
it will run thru a function,
How do I do it in Ruby code? make a global variable running through my
customized get/set procedure?
Thanks.


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