Added a "target" option to specify the target attribute for the menu links

[javiereguiluz]

This pull request finishes the work done originally by @maldoinc in #845.

[Pierstoval]

I don't like this feature. It's "specific" behavior for something a bit restrictive.

Why not add a attr option that will contain all HTML properties to the tag? (of course with the href one being overriden to avoid issues)

[ogizanagi]

I agree with @Pierstoval on this.

[javiereguiluz]

I understand the concerns of @Pierstoval and @ogizanagi ... but I still think is OK to add this small feature. I don't plan to add more configuration options for menu items, so this is the last one (and that means that we won't clutter the menu feature). Besides, we allow links to absolute URLs and external systems in the menu, so it's important to be able to open them in new tabs/windows.

The problem with attr is that it forces you to remember which options are first-level options and which ones nested inside attr. And nested arrays are ugly in YAML files. We do that when we have no other option (line type_options for form fields) but we try to avoid that as much as possible.

So, I'm going to merge this feature. But, in the future, we can reconsider this decision. And since the feature is minimal, and removing it won't break the backend, BC breaks won't matter. Thanks!

[Pierstoval]

The problem with attr is that it forces you to remember which options are first-level options and which ones nested inside attr. And nested arrays are ugly in YAML files. We do that when we have no other option (line type_options for form fields) but we try to avoid that as much as possible.

Precisely, having attr is a good standard because it allows everyone to know what's the difference between logical parameters and html parameters. attr is also used in Symfony forms with attr for widgets and label_attr for labels for example.

Here, when you add "magic" (= a seemingly "logical" option that's transformed into a basic html parameter) you induce bc breaks when the attr option is finally introduced.

I personally have to change the class of one link in some of my backends, and another will use javascript so it needs an id and an empty href attribute.

There's always room for full flexibility, especially when you follow good/standard practices that are used elsewhere the same way.

And for the And nested arrays are ugly in YAML files , there is not much solution for this. Actually, there is one: define the configuration from tagged services returning arrays (something I proposed last year many times).