Package input parameter SQL Developer - plsql

Question

I am trying to create a package in Oracle SQL Developer and want to have a public input parameter that another user can input a date to. I tried the following code -
Create PACKAGE Assignment_1_Pack is
vstartDate date := to_date('&startDate', 'DD/MM/YYYY');
vendDate date := to_date('endDAte', 'DD/MM/YYYY');
END;
When I try to run it I get the following message
Empty package Assignment_1_pack definition (no public members).
I was expecting the window that pops up to prompt for an input but I haven't used packages before so I am not sure what it is I am doing wrong

Answer 1

run set define on;
Use a command create OR REPLACE package Assignment_1_Pack ...
SET DEFINE ON/OFF toggles the substitution variables on or off. Probably the substitution of variables was turned off, so SQLDeveloper doesn't ask for the value
See this for details: https://docs.oracle.com/cd/B19306_01/server.102/b14357/ch12040.htm#sthref2736
SET DEF[INE] {& | c | ON | OFF} Sets the character used to prefix
substitution variables to c.
ON or OFF controls whether SQL*Plus will scan commands for
substitution variables and replace them with their values. ON changes
the value of c back to the default '&', not the most recently used
character. The setting of DEFINE to OFF overrides the setting of the
SCAN variable.
create OR REPLACE package ... prevents from errors in a case when the package has already been created. Simple CREATE PACKAGE xxx command fails if the package already exists. If you create the package for the first time, then all subsequent attempts will fail. Create OR REPLACE ... drops the package if it already exists, and then creates it again, so it newer fails.