Grim C++ Tales from the Crypt: The Visitor Pattern (2017)
cppcrypt.tumblr.com
Grim C++ Tales from the Crypt: The Visitor Pattern (2017)
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Re: Grim C++ Tales from the Crypt: The Visitor Pattern (2017)
#2their GDPR compliance screen is full of anti patterns. Will not read.
Re: Grim C++ Tales from the Crypt: The Visitor Pattern (2017)
#3The thing that annoys me most about this pattern is that people always miss the "there needs to be lots of things you want to perform on those thingies".
And so we end up with a huge pile of visitor code, and there is one or maybe two actual visitors.
When it would have been far easier to read and modify if it was just coded out normally.
Re: Grim C++ Tales from the Crypt: The Visitor Pattern (2017)
#4If you're like me and couldn't get past the first few slides because it's a terrible reading experience, go to the archive, which shows the whole thing in thumbnails. It makes it little better, even though the thumbnails are in reverse:
Re: Grim C++ Tales from the Crypt: The Visitor Pattern (2017)
#5If you're like me and couldn't get past the first few slides because it's a terrible reading experience, go to the archive, which shows the whole thing in thumbnails. It makes it little better, even though the thumbnails are in reverse: https://cppcrypt.tumblr.com/archive
This would definitely be better as a blog post than a dog post.
Re: Grim C++ Tales from the Crypt: The Visitor Pattern (2017)
#6If you're like me and couldn't get past the first few slides because it's a terrible reading experience, go to the archive, which shows the whole thing in thumbnails. It makes it little better, even though the thumbnails are in reverse: https://cppcrypt.tumblr.com/archive
This would definitely be better as a blog post than a dog post.
What is a dog post?
Re: Grim C++ Tales from the Crypt: The Visitor Pattern (2017)
#7Re: Grim C++ Tales from the Crypt: The Visitor Pattern (2017)
#8The thing that annoys me most about this pattern is that people always miss the "there needs to be lots of things you want to perform on those thingies". And so we end up with a huge pile of visitor code, and there is one or maybe two actual visitors. When it would have been far easier to read and modify if it was just coded out normally.
IMHO, the most important condition is the need to do different stuff on different (small) subsets of classes, typically combined with a (non-trivial) tree traversal. Otherwise, its more straightforward to add regular virtual methods.
Re: Grim C++ Tales from the Crypt: The Visitor Pattern (2017)
#9The thing that annoys me most about this pattern is that people always miss the "there needs to be lots of things you want to perform on those thingies". And so we end up with a huge pile of visitor code, and there is one or maybe two actual visitors. When it would have been far easier to read and modify if it was just coded out normally.
I’ve never considered this, but I think it’s a fair assessment! It’s particularly striking when you see a compiler with multiple visitors that are refactored into one or two visitors to reduce the number of traversals. I think I understand the cause, it’s easier to start with a visitor pattern than refactoring into a visitor pattern.
Nevertheless, for many problems, like compiler construction, I’ve never seen a pattern that matched the utility of the visitor (even outside of imperative and object-oriented patterns)
Re: Grim C++ Tales from the Crypt: The Visitor Pattern (2017)
#10C++ match expressions would make std::variant a really nice alternative.
I assume there is already a proposal out?