Is it possible to mimic sed's "change line" feature?

Question

I'd like to write an elisp function that allows me to replace any line in my buffer matching a regex pattern <PATTERN> with text <TEXT>. In other words, if line N matches <PATTERN>, then line N is replaced with <TEXT>.

For example, if <PATTERN> is ^foo and <TEXT> is bar, then running the elisp function within the buffer

Arcu ante habitasse inceptos congue.
Odio magnis at aenean at est.
foo eget, eu vitae.
Class.
Adipiscing dis donec tellus imperdiet curae.
fooSem sit tristique lacus ut porta accumsan.
Amet ad duis velit sit amet.

would change the buffer to

Arcu ante habitasse inceptos congue.
Odio magnis at aenean at est.
bar
Class.
Adipiscing dis donec tellus imperdiet curae.
bar
Amet ad duis velit sit amet.

This is exactly the behavior of the sed command sed '/^foo/c\bar'.

Answer 1

Is it possible to…

The answer to this type of question is always yes.

In your case, just run (replace-regexp "^foo.*$" "bar"). You can do this interactively with query-replace-regexp, which prompts you to verify each match. This helps prevents mistakes. It is bound to C-M-% by default.