Easier string concat in PL funcs?

After for the umpteenth time bashing my head against a wall developing
some PL funcs that use dynamic SQL, going plain bonkers trying to
build the query string; I came up with a function like the one below
to take a string with placeholders, an array of values to be
interpolated and a placeholder char.  (This may appear Pythonish to
some.

Question: Am I overlooking a simple way of doing this?

As in; raise notice 'Foo % %', v_var1, v_var2;


create function make_string(v_template text, v_vars text[], v_placeholder char)
returns text
as $$

declare
    v_temp text[] := string_to_array(v_template, v_placeholder);
    v_output text[];

begin
    if array_upper(v_vars, 1) + 1 != array_upper(v_temp, 1) then
        raise exception 'Too many vars; should be equal to placeholders "%" in string', v_placeholder;
    end if;

    for i in 2 .. array_upper(v_temp, 1) * 2 by 2 loop
        v_output [i - 1] := v_temp[i / 2];
        v_output [i] := v_vars[i / 2];
    end loop;

    return array_to_string(v_output, '');

end

$$
language plpgsql;


The above function makes possible to do something like this shown
below wich for complex dynamic SQL strings, can be a lot easier to
create than with the usual combo of string constants pasted together
with PL vars using ||.

execute make_string($$
    create table fooschema.%
    ;
    create rule %
    as on insert  to fooschema.%
    where %
    do whatever
    ;
$$,
array [
    v_tablename,
    v_rulename,
    v_tablename,
    v_conditions
],
'%'
);
--
...Still not exactly simple, I realize :-)

Thanks

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