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From Craig L Russell <Craig.Russ...@Sun.COM>
Subject Re: Enforcing JDK 1.4-specific modules
Date Wed, 13 Jun 2007 16:08:36 GMT
Is this a bug? I'd think that setting the source 1.4 flag would  
disallow compiling a file that contained a reference to 1.5 methods  
in the java.lang package. I'd have to look at any differences between  
the maven project.properties, the maven pom.xml, and the javac - 
source techniques. I'm pretty sure that javac -source chooses the  
right compile-time library (IIUC this technique is used by the Derby  
project to make sure they get the right java.sql jars to compile  
against).

I'm copying the Derby dev alias because I think they've solved this  
problem.

If we can't find a solution with flags, I think we should find  
ourselves a 1.4 jar file and check it into the project. We don't need  
to ship it (indeed we cannot) but using it for compiling should not  
be an issue.

Craig

On Jun 13, 2007, at 8:12 AM, Marc Prud'hommeaux wrote:

>
>> Is that what we want?
>
> No, but since there is no public maven-friendly JDK 1.4 runtime jar  
> that I am aware of, and since I bet that Apache wouldn't want us to  
> commit it to the repository, I don't think there is any solution  
> that wouldn't require the developer to perform a manual  
> installation of JDK 1.4 in some pre-determined location. And I'm  
> personally loathe to add any environmental requirements that  
> hinders new developers from being able to build OpenJPA.
>
>
>
>
> On Jun 13, 2007, at 10:50 PM, Craig L Russell wrote:
>
>> Hi Marc,
>>
>> Ah, you are right. I looked at the projects and didn't see the  
>> project.properties where the compile.source and target properties  
>> are. They are also in the pom.xml though in the build plugins.
>>
>> But why should this be a choice of developers? I'd think that  
>> either we would want to enforce this restriction for the project  
>> or not. If we leave it up to developers' choice then someone will  
>> eventually have to come around and fix up the 1.5 dependencies. Is  
>> that what we want?
>>
>> Craig
>>
>> On Jun 13, 2007, at 7:35 AM, Marc Prud'hommeaux wrote:
>>
>>> Craig-
>>>
>>> We were already setting the "source" and "target" flags to "1.4"  
>>> for the 1.4 modules, but that only enforces language-level  
>>> restrictions (e.g., it would raise an error if you tried to use  
>>> generics or autoboxing), it doesn't check to make sure you didn't  
>>> use an API method that doesn't exist in 1.4. In order to validate  
>>> that, say, you didn't call String.contains() (which is new in  
>>> 1.5), you need to use the bootclasspath argument to provide the  
>>> 1.4 runtime jar so that that level of verification can take place.
>>>
>>>
>>>
>>> On Jun 13, 2007, at 10:21 PM, Craig L Russell wrote:
>>>
>>>> There is a maven flag that you can put into maven's  
>>>> project.properties that specifies the level of jdk to use for  
>>>> that project.
>>>>
>>>> maven.compile.source = 1.4
>>>> maven.compile.target = 1.4
>>>>
>>>> This can be dropped into those projects that we want to compile  
>>>> with 1.4. This will enforce the dependency at compile time.
>>>>
>>>> Craig
>>>>
>>>> On Jun 13, 2007, at 12:55 AM, Marc Prud'hommeaux wrote:
>>>>
>>>>>
>>>>> We recently had some problems where JDK 1.5-specific methods  
>>>>> (e.g., String.contains(String)) were slipping into JDK 1.4- 
>>>>> specific modules. This isn't a problem for stand-alone OpenJPA  
>>>>> (whose only implementation is JPA, which is JDK 1.5-dependent),  
>>>>> but other products built on OpenJPA may still support JDK 1.4.
>>>>>
>>>>> To that end, I've added a 'java14.jar' property to the pom.xml  
>>>>> files that can be used to specify the location of the JDK 1.4  
>>>>> runtime jar, against which we will compile the JDK 1.4-specific  
>>>>> modules. Since the location of the JDK 1.4 runtime jar is  
>>>>> platform- and installation- dependent, we can't just rely on a  
>>>>> single location (nor is there any maven-friendly JDK 1.4  
>>>>> runtime jar that I am aware of), the flag needs to be specified  
>>>>> manually.
>>>>>
>>>>> Note that the flag will be silently ignored when it is  
>>>>> unspecified, which I expect will be the common case for most  
>>>>> OpenJPA developers. You only need to use it if you are  
>>>>> interested in ensuring that any code you add to JDK 1.4 modules  
>>>>> won't break 1.4 compatibility.
>>>>>
>>>>>
>>>>
>>>> Craig Russell
>>>> Architect, Sun Java Enterprise System http://java.sun.com/ 
>>>> products/jdo
>>>> 408 276-5638 mailto:Craig.Russell@sun.com
>>>> P.S. A good JDO? O, Gasp!
>>>>
>>>
>>
>> Craig Russell
>> Architect, Sun Java Enterprise System http://java.sun.com/products/ 
>> jdo
>> 408 276-5638 mailto:Craig.Russell@sun.com
>> P.S. A good JDO? O, Gasp!
>>
>

Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:Craig.Russell@sun.com
P.S. A good JDO? O, Gasp!


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