Passing a code block as an anon. function

I've managed to do what you want with a eval hack. With this I lay warned that eval is insecure and you should avoid at all costs. Having that said, if you trust your code won't be abused, you can use this:

wrap_this(){
    run_something
    eval "$(cat /dev/stdin)"
    run_something_else
}

This allows you to run code as follows:

wrap_this << EOF
    my function
EOF

Not exactly ideal, since the inner block is a string, but does create reuse.

No, bash doesn't have anonymous functions. It is however possible to pass a function name and arguments as strings and have bash call it.

function wrap() {
    do_before
    "$@"
    do_after
}

wrap do_something with_arguments

This is however, somewhat limited. Dealing with quoting can become a problem. Passing more than one command is also a complication.

You can put code in a string and pass it to eval or sh or simply interpolate it.

perform () {
  "$@"
}

perform echo "moo"

You can quickly end up in deep quoting trouble, though.