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From Regis <xu.re...@gmail.com>
Subject Re: About JDB's expression calculation
Date Wed, 07 Jul 2010 01:31:52 GMT
On 2010-07-05 21:28, Daniel Gong wrote:
> Back to this question, I still do not find a proper solution.
>
> I think expressions like "object.method()" can only be evaluated at the
> debuggee side, because the debugger does not have enough information to
> evaluate it. Then, if this kind of expression can be evaluated at the
> debuggee side, expressions like "a+b" are supposed to be able to be
> evaluated too.

"object.method()" can be done by jdwp command ObjectReference::InvokeMethod; 
primitive type operations, such as "3 / 4", can be done in debugger side, but I 
guess you have to parse it yourself.

>
> I'm not sure whether my understanding is right. If I'm right, there should
> be some interface at the debugger side that can evaluate a valid java
> expression, does anyone know what it is? If I'm wrong, is there any library

At least there is no jdwp commands can do this AFAIK.

> that I can use to parse a java expression and evaluated it as Regis said?
>
> Best wishes
> Daniel Gong
>
>
> On Wed, Jun 9, 2010 at 9:27 AM, Regis<xu.regis@gmail.com>  wrote:
>
>> On 2010-06-08 19:07, Daniel Gong wrote:
>>
>>> Hi everyone,
>>>
>>> As you know I'm now preparing to develop jdb command line tool. I've
>>> encountered a problem. JDB has the functionality of display value of a
>>> java
>>> expression, but how can I calculate the value from an expression string?
>>> I've thought about the problem for days and still cannot figure it out. I
>>> need some help from you. Thanks :)
>>>
>>> Best wishes
>>> Daniel Gong
>>>
>>>
>> I guess you need to parse the string to find out which part should be
>> calculated at debuggee side, and which can be done at jdb side.
>>
>> --
>> Best Regards,
>> Regis.
>>
>


-- 
Best Regards,
Regis.

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