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https://issues.apache.org/jira/browse/DERBY-3069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12526851
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Rick Hillegas commented on DERBY-3069:
--------------------------------------
Thanks for helping me puzzle through these issues.
Just to be clear, I don't want to tackle varargs in CREATE FUNCTION statements.
I think that lies outside the SQL standard. However, I think that the Derby SQL
interpreter should be able to resolve method calls which the Java compiler can
handle. So, for example, given the following method declaration in a Java class
public static String varArgsFunc( String... args )
I think that the following bindings should be meaningful and should be resolved
when the functions are actually invoked:
create function twoArgs( arg1 varchar( 10 ), arg2 varchar( 10 ) )
returns varchar( 40 )
language java
parameter style java
no sql
external name 'z.varArgsFunc'
;
create function threeArgs( arg1 varchar( 10 ), arg2 varchar( 10 ), arg3
varchar( 10 ) )
returns varchar( 40 )
language java
parameter style java
no sql
external name 'z.varArgsFunc'
;
Part 13 of the SQL standard is a little vague, but the resolution rules in the
last paragraph of section 4.2.2 lead me to believe that the intention is that
the SQL interpreter should follow the method resolution rules used by Java
itself. I may not know where to look, but it seems to me that the Standard is
vague about which version of Java is intended.
I have no problem classifying this as an improvement rather than a bug.
However, I think that for customers who are using Java 5 or Java 6, the
description of CREATE FUNCTION in the Reference Guide is vague and misleading
enough that something ought to be done: either tighten up the documentation or
implement varargs resolution. I think that the latter makes Derby more useful.
> Derby does not resolve functions bound to methods with varargs.
> ---------------------------------------------------------------
>
> Key: DERBY-3069
> URL: https://issues.apache.org/jira/browse/DERBY-3069
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 10.0.2.0, 10.0.2.1, 10.1.1.0, 10.1.2.1, 10.1.3.1,
> 10.2.1.6, 10.2.2.0, 10.3.1.4
> Reporter: Rick Hillegas
> Attachments: z.java, z.sql
>
>
> Varargs were added in Java 5. It would be nice if Derby let you invoke a
> function bound to a method with a variable length argument list. The
> Reference Guide states a small number of restrictions for methods which can
> be invoked as Derby functions: They must be public, static, and not have
> arguments which are long datatypes. I see no reason that Derby shouldn't be
> able to resolve and invoke functions which are bound to methods which don't
> suffer these limitations but which have variable argument lists.
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