Please review: JDK-8178725: provide way to link to external documentation

[Magnus Ihse Bursie]

On 2017-04-20 20:02, Jonathan Gibbons wrote:
> David, Magnus,
>
> Yes, this is somewhat Oracle-specific (more accurately it is 
> JDK-specific, which is why this is a proposed to be a JDK build-time 
> taglet, and not a standard tag in the standard doclet), but it is no 
> worse than the explicit Oracle-specific URLs that have been used up to 
> now, or the relative links using {@docRoot}/../stuff  which assume 
> that "stuff " is available nearby somehow.  I would also go further 
> and say this is better that the existing methodology because it 
> abstracts all the linking to a single taglet, removing it from inline 
> in the doc comments. 
I agree, it's in no way worse than what already existed. But it shed 
light on the somewhat unclear division between online Oracle 
documentation and OpenJDK documentation.

Just to be clear: I do not oppose the fix. It looks good to me.

If anything, there was a bit of a clash between on the one hand 
providing a means for overriding the URL, but on the other hand not 
really making it as general as it could be. Either removing the 
possibility to override it (and, as you say, let an alternative 
implementation change the code of the taglet itself), or as Roger 
suggest, using a more general mechanism like MessageFormat would have 
the code make slightly more sense. The simplest way is probably to skip 
the property override, which doesn't get used anyhow right now (and 
therefore suspect according to "if you don't test it, it is (or will 
become) broken").

/Magnus

> Yes, the currently proposed taglet may assume the existence of  single 
> "base URL", but anyone with an alternate implementation of OpenJDK 
> could change the impl of the taglet to use any other mechanism to 
> establish the link. Doing a "strings in switch" on the identifier to 
> select a URL comes to mind, and avoids anyone having to edit the main 
> source doc comments.
>
> -- Jon
>
>
>
> On 04/19/2017 01:37 PM, David Holmes wrote:
>> On 20/04/2017 3:50 AM, Kumar Srinivasan wrote:
>>>
>>> We could potentially make the default URL to be "some" cgi url,
>>> and have the build system specify the  URL all the time, in our
>>> case it would be the Oracle documentation URL.
>>>
>>> Would this be an acceptable approach ?
>>
>> I'm not sure what you mean. I have a hard time seeing how a simple 
>> identifier (that will be fixed in the file using the taglet) can be 
>> attached to an arbitrary URL to yield a valid result. As Magnus said, 
>> being able to change the URL is good, but it still requires the same 
>> "kind" of URL where the identifier is used as a key.
>>
>> Imagine you have all the documentation locally on your machine then 
>> try to figure out how you could link to other local documentation 
>> using this scheme.
>>
>> David
>>
>>> Kumar
>>>
>>>> On 19/04/2017 9:26 PM, Magnus Ihse Bursie wrote:
>>>>> On 2017-04-18 19:44, Kumar Srinivasan wrote:
>>>>>> Hello,
>>>>>>
>>>>>> As explained in the JBS issue [1], this new taglet enables API
>>>>>> documents
>>>>>> to contain the extLink tag to link external sources.
>>>>>>
>>>>>> Please review the webrev [2].
>>>>> Changes looks good.
>>>>>
>>>>> Just a reflection: This is heavily biased to Oracle documentation. 
>>>>> Even
>>>>> if it's possible to override the URL via a system property, it 
>>>>> assumes
>>>>> the Oracle URL format and id name. Just wondering a bit how that fits
>>>>> with the OpenJDK philosophy.
>>>>
>>>> I have to agree, this is not at all general purpose but totally Oracle
>>>> documentation centric.
>>>>
>>>> David
>>>> -----
>>>>
>>>>
>>>>> /Magnus
>>>>>
>>>>>>
>>>>>> Thanks
>>>>>> Kumar
>>>>>>
>>>>>> [1] https://bugs.openjdk.java.net/browse/JDK-8178725
>>>>>> [2] http://cr.openjdk.java.net/~ksrini/8178725/webrev.00/
>>>>>
>>>
>