Forum: JRuby const_get() missing from jruby/src/jruby/java/java_package_module_template.rb does not include an im

jruby/src/jruby/java/java_package_module_template.rb does not include
an implementation of const_get().


AFAIK the solution is to add

    def const_get(const)
      JavaUtilities.get_proxy_class(@package_name + const.to_s)
    end

to JavaPackageModuleTemplate


The challenge is this file is in the jruby.jar so it makes it tough to
monkey patch...

Any ideas ?



use case:

Leveraging extends and include`s, I've added ActiveModel support to
java pojos. This works well and I can now use pojos as full fledged
models in rails apps. This is quite useful for integration.
see
http://yehudakatz.com/2010/01/10/activemodel-make-...

However, some gems (ActiveSupport) pass the class
intoActiveSupport::Dependencies.constantize(resource_class_name). This
in turn callsactive_support/inflector/methods.constantize() for each
module which finally calls constant.const_get().

I've added a few trace statements and have seen the following

resource_class_name=::Java::ComMyCoPocModel::CardApplicant
constantize Object Java
constantize Java ComMyCoPocModel
constantize Java::ComMyCoPocModel CardApplicant
ArgumentError: Java package com.myco.poc.model' does not have a 
methodconst_get'

Looking at the code JavaPackageModuleTemplate, would an implementation
of const_get() be similar toconst_missing() ie call to
JavaUtilities.get_proxy_class


-Brian Walsh

I think we can consider adding:

method_alias :const_get, :const_missing

The const_missing already throws a NameError and is what you are
monkey patching in.  Is it weird that this will try and force a load
of a new package or java Class?  Not so much in the case that these
packages cannot know what constants they actually might have.

The only downside I can see to this is now people cannot have a class
or package called const_get, but this seems exceedingly unlikely to
me.  Can you think of any other downsides to us just adding this to
JRuby itself?

I sort of feel the contract for constants should be
const_missing/const_get/const_set, but const_set does not seem to have
meaning for this scenario.

-Tom

On Tue, Dec 11, 2012 at 12:25 AM, Brian Walsh <brian@bwalsh.com> wrote:
> to JavaPackageModuleTemplate
>
>
> JavaUtilities.get_proxy_class
>
>
> -Brian Walsh
>
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> To unsubscribe from this list, please visit:
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--
blog: http://blog.enebo.com       twitter: tom_enebo
mail: tom.enebo@gmail.com

Thomas,

Thank you.  I agree about the contract for constants.  I think loading
the java class would be an expected behavior.

I can try the alias you suggest asap and let you know.


-Brian Walsh