Re: [HACKERS] Patch for user-defined C-language functions

Andreas Zeugswetter wrote:
>
> But I think the intuitive Syntax in SQL would use ():
>
> CREATE FUNCTION mytype3 ( mytype2 )
> RETURNS mytype3
> AS 'mytypes.so(mytype2_to_mytype3)'
> LANGUAGE 'C'
>
> Syntax:
> AS <link_file>[(symbol_name)]
>
> This is also how Illustra and now Informix does it.
> (Instead of AS they say EXTERNAL NAME)
>

The syntax

AS <link_file>[(symbol_name)]

would be easy to implement provided I could write your example as

CREATE FUNCTION mytype3 ( mytype2 )
RETURNS mytype3
AS 'mytypes.so'('mytype2_to_mytype3')
LANGUAGE 'C'

That way link_file and symbol_name both look like string tokens to
the parser. If it is implemented the way you write in the example with

'mytypes.so(mytype2_to_mytype3)'

Then the parser sees the arguement of the AS clause as a single
string token which would have to be parsed separately. Also, there is
some ambiguity in this form as to whether the string

'mytypes.so(mytype2_to_mytype3)'

is a single filename, or a filename and a link symbol

Bernie