How do you backup functions only?

We have a reasonably sized postgres database where we want to make
coding changes to the functions within it.
Before we alter the functions, it would be a good idea to backup the
current functions in the database. The database itself is too large to
do a full backup every time we make a coding change.
We currently use the following script to backup (some of the) functions.

bash-3.00$ cat backup_phpcron.sh
DATE=`date "+%Y%m%d"`

if [ -r phpcron-$DATE.sql.gz ]
then
    echo "ABORTED phpcron-$DATE.sql.gz already exists"
    exit 1
fi

psql -At <<-'!' | gzip -c > phpcron-$DATE.sql.gz || exit 1
\df+ avail_oneway
\df+ avail_return
\df+ clear_flightdata
\df+ clear_flightdata_update
\df+ load_flights
\df+ load_flights_update
\df+ load_prices
\df+ load_prices_update
\df+ load_routes
\df+ prepare_avlpkgs
\df+ prepare_avlpkgs_update
!

This creates a non-restorable snapshot of the functions. Is there a way
to output the functions (only) so that they can be restored in one easy
operation if there is an error in the new code? An option to pg_dump
that I have missed perhaps?

Thanks in advance.

--
Andrew Walmsley
Software Development
Travel Technology Systems Ltd.
2 Nile Close, Riversway
Preston, PR2 2XU
Tel: 01772 766800
Fax: 01772 766801

(please note the new address and contact number)

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