A ConsString Gotcha

[Rick Bullotta]

I do think it is a reasonable requirement when using any arbitrary library that in some cases a wrapper would be required.  Having a method signature with "Object" is not exactly ideal for even weakly typed interaction...kinda like an XML schema with "xsd:any".  I think the key is to avoid having to make the script developer do goofy stuff.  If it requires a developer to wrap some 3rd party library to provide necessary typing or type munging in some edge cases, that certainly seems reasonable, doesn't it?

-----Original Message-----
From: nashorn-dev-bounces at openjdk.java.net [mailto:nashorn-dev-bounces at openjdk.java.net] On Behalf Of Tal Liron
Sent: Sunday, October 13, 2013 12:42 PM
To: nashorn-dev at openjdk.java.net
Subject: Re: A ConsString Gotcha

Your proposal solves the generics problem nicely enough, but many 3rd party libraries out there have methods with Object argument signatures.

I still think that blanket conversion is best, configurable with a flag.

The performance issue might be fixable like so: if ever a ConsString needs to be converted to a String, it would happen once and only once, effectively internally replacing the ConsString with a String instance. 
The performance hit would be momentary. And again, can be disabled with a flag.

On 10/14/2013 12:28 AM, Jim Laskey (Oracle) wrote:
> The complication there is that every time you have an Object 
> argument/field you would have to have an if instanceof ConsString cast 
> String sequence, which is a huge performance hit.  ConsString was 
> introduced to significantly improve performance (high frequency 
> operation), so it's a bit of a dilemma.  The team has debated this 
> several times.  It might be better in the long run to be able to 
> properly declare the HashMap with something like;
>
> 	var StringHashMap = Java.type("java.util.HashMap<java.lang.String, 
> java.lang.Object>");
>
> or even better
>
> 	var JObject = Java.type("java.lang.Object");
> 	var JString = Java.type("java.lang.String");
> 	var StringHashMap = Java.type("java.util.HashMap", JString, JObject);
>