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From "Geir Magnusson Jr." <g...@pobox.com>
Subject Re: [vmi] showing help text
Date Tue, 19 Sep 2006 17:31:22 GMT

On Sep 19, 2006, at 12:24 PM, Tim Ellison wrote:

> Geir Magnusson Jr. wrote:
>> On Sep 19, 2006, at 11:02 AM, Tim Ellison wrote:
>>> Geir Magnusson Jr. wrote:
> <snip>
>>>> I'm going to modify the launcher to pass "-help" into the VM  
>>>> when it's
>>>> been named "java*" so that it behaves like the tools that come  
>>>> with the
>>>> Sun's, BEA's and IBM's impelmentation.
>>>
>>> As I mentioned before, you if you pass "-help" or "-showversion"  
>>> in the
>>> creation of the IBM or Sun VM you will get an error, e.g.:
>>>
>>>   C:\temp\sample>test
>>>   JVMJ9VM007E Command-line option unrecognised: -help
>>>   Failed to create VM with rc=-6.
>>>
>>> These command-line flags are handled by the launcher (not the VM).
>>
>> I need to test that for Sun via a launcher, as just doing "java - 
>> help"
>> w/ the sun JRE works as expected - it prints help.
>
> Sun's VM (1.5.0_06) does the same thing:
>   C:\temp\sample>test
>   Unrecognized option: -help
>   Failed to create VM with rc=-1.
>
> BTW I'm using the test program I posted here, but passing in "-help":
> http://mail-archives.apache.org/mod_mbox/incubator-harmony-dev/ 
> 200609.mbox/%3c45092A90.8010709@gmail.com%3e

Why would one even want to launch Sun this way?  I mean, I figure the  
lack of support of our classlibrary would be a bigger obstacle to use  
than simply not supporting "-help"

>
>>> Since in Harmony there is not a 1:1 correlation of launcher to VM
>>> implementation you will have to either print out generic help in the
>>> launcher (bad) or go for an extension to the VM interface to get/ 
>>> print
>>> help text.
>>
>> How about passing -help to the VM?  I don't grok the downside to  
>> this.
>> DRLVM works this way now.   that way any localization issues are  
>> up to
>> the VM provider.
>
> I'm just pointing out that not all VMs will grok that option, so the
> launcher should not assume they will.
>

Agreed.  But our launcher is for Harmony, and there are already a  
bunch of pre-reqs...

> We can add a requirement to the VMI that VMs can answer/print their  
> help
> text, but right now we have no such thing.  Existing VMs will fail to
> initialize (unless you set ignoreUnrecognized, in which case you won't
> get help text of course).

I'm still confused.  When you say "existing VMs". you mean J9?   
Because besides DRLVM, there are no others that work w/ the launcher...

>
>> Having the launcher print out help based on the executable name  
>> would be
>> bad - it has to be some thing else.
>
> I don't see that we could do that anyway, since the launcher is always
> java.exe, and different VMs will have different help text.

Right.

What I mean is some scheme where we base help text on exe name, like  
"javac" "java" "javah" etc...

So to try to drive this to conclusion, I don't get it - what would be  
wrong with adding "supports all options passed through the launcher  
except vmdir: and vm:" to our list of things that a harmony- 
supporting VM does?

geir

>
> Regards,
> Tim
>
>>> I believe that you could write a useful generic implementation of
>>> version info since VMs put that into system properties.
>>
>> True - we could solve the version problem that way...
>>
>> geir
>>
>>>
>>> Regards,
>>> Tim
>>>
>>>> IOW, I think that users expect :
>>>>
>>>> ./java
>>>>
>>>> ..... print help here....
>>>>
>>>>
>>>> But we do need to hunt down why it exits so ungracefully - this  
>>>> is a
>>>> good test case showing problems since it's so simple.
>>>>
>>>> geir
>>>>
>>>>
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>>>>
>>>>
>>>
>>> -- 
>>> Tim Ellison (t.p.ellison@gmail.com)
>>> IBM Java technology centre, UK.
>>>
>>> -------------------------------------------------------------------- 
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>>
>>
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>>
>
> -- 
>
> Tim Ellison (t.p.ellison@gmail.com)
> IBM Java technology centre, UK.
>
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>


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