def assignable(lhs, value = nil)
id = lhs.to_sym
id = id.to_sym if Sexp === id
raise SyntaxError, "Can't change the value of #{id}" if
id.to_s =~ /^(?:self|nil|true|false|__LINE__|__FILE__)$/
result = case id.to_s
when /^@@/ then
asgn = in_def || in_single > 0
s((asgn ? :cvasgn : :cvdecl), id)
when /^@/ then
s(:iasgn, id)
when /^\$/ then
s(:gasgn, id)
when /^[A-Z]/ then
s(:cdecl, id)
else
case self.env[id]
when :lvar then
s(:lasgn, id)
when :dvar, nil then
if self.env.current[id] == :dvar then
s(:lasgn, id)
elsif self.env[id] == :dvar then
self.env.use(id)
s(:lasgn, id)
elsif ! self.env.dynamic? then
s(:lasgn, id)
else
s(:lasgn, id)
end
else
raise "wtf? unknown type: #{self.env[id]}"
end
end
self.env[id] ||= :lvar
result << value if value
return result
end