埃菲尔铁塔：无效安全性，一种简洁的方法来测试对象是否存在，然后调用其功能

Question

I was wondering if there is a clearer statement then

if not attached foo then
    create foo
end
if attached foo as l_foo then
    l_foo.bark
end

as

if not attached foo then
    create foo
    foo.bark
else
    foo.bark
end

would repeat the foo.bark and obviously I want to avoid it... and even the last statement won't compile with void-safety as foo on else could be void...

Answer 1

To avoid code duplication and multiple tests, the following code could be used:

l_foo := foo
if not attached l_foo then
    create l_foo
    foo := l_foo
end
l_foo.bark