Forum OpenACS Development: pl/pgsql porting style question

It's me again.

I am still working on static-pages. I have come to come function calls that have several values that are passed in as NULLs.  But when I try to pass them as NULLs the parsers gets confused and can't find the function.

Is it better to create an overloaded function that just needs the specific parameters I am passing?

Uh oh. I ported a function call (in content::new_item) in cms/tcl/form-procs.tcl exactly like that last night. I'm not sure how to do it another way.

If someone would like to take a look and give me some ideas, that'd be really nice. You can see the diff right here: https://openacs.org/sdm/entry-history-diff.tcl?current_entry=FILE+%2Fopenacs-4%2Fpackages%2Fcms%2Ftcl+form-procs.tcl&new_release=1.6&package_id=9&old_release=1.5

I think when you call a function with a NULL param, pl/pgsql treats the param as type 'unknown' and matches it to any type in the function's parameter list. The problem comes when you have so many NULLs that more than 1 function would match. In that case, you can cast your NULL so that the proper function is called.

Example:

create function vk_test(integer,varchar)
returns integer as '
begin
    raise notice ''integer first function'';
    return 0;
end;' language 'plpgsql';

create function vk_test(varchar,integer)
returns integer as '
begin
    raise notice ''varchar first function'';
    return 0;
end;' language 'plpgsql';

# select vk_test(1, NULL);
NOTICE: integer first function

# select vk_test(NULL, 1);
NOTICE: varchar first function

# select vk_test('a'::varchar, NULL);
NOTICE: varchar first function

# select vk_test(NULL, 'a'::varchar);
NOTICE: integer first function

# select vk_test(NULL, NULL);
ERROR: Function 'vk_test(unknown,unknown)' does not exist

# select vk_test(NULL::integer, NULL::varchar);
NOTICE: integer function

Using explicit casting of nulls allows you to choose the function with the signature that you want.

Vinod, thanks a lot. I imagined this would be the case, but wasn't sure. Thanks for the nice example.

Don, I understood you. I agree with you. Thanks a lot too.