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Re: Comparing some of the ways to create objects

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Sat, 9 Apr 2016 16:46:45 -0000 (UTC), /Scott Sauyet/:
> Stefan Ram wrote:
>> Scott Sauyet wrote:
>>
>>> But the privacy offered by these techniques, even without a keyword is
>>> actually much stronger than that offered by Java or C# (I don't know
>>> about C++.)  In those languages, you can use reflection to to still get
>>> at the field.  In Javascript closure-based privacy, it's really hidden.
>>
>> Java programs can be run with a security manager, and IIRC there is a
>> »suppressAccessChecks« permission that can be denied to deny access to
>> private fields via reflection.
>> (I am not sure about this, I haven't tested it today.)
>
> I'm more than six years out from regularly working with Java, so I may be
> a little rusty.  But I believe that field is precisely the reverse: a
> tool to _allow_ otherwise restricted code from viewing private or
> protected members.  That's certainly how the Javadocs seem to read.  [1]
>
>    [1]: <http://docs.oracle.com/javase/7/docs/api/java/lang/reflect/ReflectPermission.html>

No contradiction here.  While the default security manager, or may 
be better stated having no security manager when you run a program 
from the command line may allow you to suppress access checks for 
private fields of any class via refection, running a code inside an 
application or applet container may have a security manager 
installed which prohibits the user code from doing it – at least for 
framework/container (provided/built-in) classes (vs. user code 
classes).  The security manager is standard feature of the Java 
sandboxing model.  See that trying to override access checks may 
still fail:

http://docs.oracle.com/javase/7/docs/api/java/lang/reflect/AccessibleObject.html#setAccessible%28boolean%29

> First, if there is a security manager, its checkPermission method
> is called with a ReflectPermission("suppressAccessChecks")
> permission.
>
> Throws:
>     SecurityException - if the request is denied.

java.lang.reflect.Field is a subclass of AccessibleObject.

-- 
Stanimir

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Comparing some of the ways to create objects John Harris <niam@jghnorth.org.uk.invalid> - 2016-04-03 16:09 +0100
  Re: Comparing some of the ways to create objects Scott Sauyet <scott@sauyet.com> - 2016-04-04 04:15 +0000
    Re: Comparing some of the ways to create objects Stefan Weiss <krewecherl@gmail.com> - 2016-04-04 15:20 +0200
      Re: Comparing some of the ways to create objects Scott Sauyet <scott@sauyet.com> - 2016-04-05 04:04 +0000
    Re: Comparing some of the ways to create objects John Harris <niam@jghnorth.org.uk.invalid> - 2016-04-04 16:48 +0100
      Re: Comparing some of the ways to create objects Scott Sauyet <scott@sauyet.com> - 2016-04-05 04:04 +0000
        Re: Comparing some of the ways to create objects John Harris <niam@jghnorth.org.uk.invalid> - 2016-04-07 15:07 +0100
          Re: Comparing some of the ways to create objects Scott Sauyet <scott@sauyet.com> - 2016-04-08 01:10 +0000
            Re: Comparing some of the ways to create objects John Harris <niam@jghnorth.org.uk.invalid> - 2016-04-08 14:55 +0100
    Re: Comparing some of the ways to create objects Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-04-04 22:12 +0200
      Re: Comparing some of the ways to create objects John Harris <niam@jghnorth.org.uk.invalid> - 2016-04-05 09:57 +0100
    Re: Comparing some of the ways to create objects John Harris <niam@jghnorth.org.uk.invalid> - 2016-04-06 16:41 +0100
      Re: Comparing some of the ways to create objects Scott Sauyet <scott@sauyet.com> - 2016-04-06 23:42 +0000
        Re: Comparing some of the ways to create objects John Harris <niam@jghnorth.org.uk.invalid> - 2016-04-07 16:09 +0100
          Re: Comparing some of the ways to create objects Scott Sauyet <scott@sauyet.com> - 2016-04-08 02:05 +0000
            Re: Comparing some of the ways to create objects John Harris <niam@jghnorth.org.uk.invalid> - 2016-04-08 15:43 +0100
              Re: Comparing some of the ways to create objects Scott Sauyet <scott@sauyet.com> - 2016-04-09 00:01 +0000
                Re: Comparing some of the ways to create objects Scott Sauyet <scott@sauyet.com> - 2016-04-09 16:46 +0000
                Re: Comparing some of the ways to create objects Scott Sauyet <scott@sauyet.com> - 2016-04-10 16:51 +0000
                Re: Comparing some of the ways to create objects Stanimir Stamenkov <s7an10@netscape.net> - 2016-05-08 17:27 +0300
                Re: Comparing some of the ways to create objects John Harris <niam@jghnorth.org.uk.invalid> - 2016-04-10 11:31 +0100
                Re: Comparing some of the ways to create objects John Harris <niam@jghnorth.org.uk.invalid> - 2016-04-10 11:52 +0100

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