How does form_for work?

I was just reading the documentation for "form_for" and I noticed that
it said: "Worth noting is that the form_for tag is called in a ERb
evaluation block, not an ERb output block."

Being a curious sort of guy, I wonder how this works...
If it's not in an output block, how does the appropriate markup get rendered?
If I wanted to figure this out myself, where would I look?

--wpd

http://api.rubyonrails.org/classes/ActionView/Helpers/FormHelper.html#M000920

The reason it says that is because contrary to what would seem
"normal" in rails at first glance, since the form_for tag outputs
Markup, you would put <%= %> around it. Since it's an Block however,
it's just <% %> with a closing <% end %>

That's all the note is making you aware of.

Yes, I understood the note. I'm just curious... How does form_for _do_ that?

--wpd

Oh, now I see it...
form_for calls concat(sometext, binding) which is the equivalent,
through some sort of Ruby/ERb magic to <%= sometext %>.

OK, curiosity bump satisfied... now back to my regularly scheduled program.

--wpd