POSIX compliant way to see if a function is defined in an sh script

Question

I\'m after THE proper way to see if a function is defined or not. A POSIX compliant way.

__function_defined() {
    FUNC_NAME=$1
    d=$(declare -f $FUNCNAME         


        

Answer 1

I have found a POSIX compliant way

if [ "$(command -v $FUNC_NAME)x" != "x" ]; then
    echo " * INFO: Found function $FUNC_NAME"
    return 0
fi

The question now, Is there a better solution?