CREATE OR REPLACE FUNCTION enumtest(anyenum) RETURNS text AS

$$

SELECT $1::text;

$$ LANGUAGE SQL;

pgsql=#  CREATE TYPE ecolor AS ENUM ('white','green','blue');

CREATE TYPE

pgsql=# 

pgsql=#  CREATE TYPE esize AS ENUM ('small','middle','big');

CREATE TYPE

pgsql=# 

pgsql=# select enumtest(ecolor('white'));

 enumtest

----------

 white

(1 row)

pgsql=# select enumtest(ecolor('green'));

 enumtest

----------

 green

(1 row)

pgsql=# 

pgsql=# select enumtest(esize('middle'));

 enumtest

----------

 middle

(1 row)

pgsql=#