Re: Late binding of integer constants?

Petter,

During compile time a constant (final) static field were used, so javac
inline the value. At runtime the class SpHttpStatus is not used. I believe
that the unique way to extract the info that the constant came from
SpHttpStatus class is by source code analysis.

But the ibrary can init the constant in a static block, and the inline will
not occur. The JaCoCo guys did some think like this: see
https://github.com/jacoco/jacoco/pull/474

On Thu, Nov 16, 2017, 11:35 AM <[email protected]> wrote:

> Hi,
>
> The following source code:
>
> if (response.getStatus() == SpHttpStatus.SC_OK)
>
> Leads to the following byte code:
>
>          1: invokevirtual #3                  // Method /redacted/
> Response.getStatus:()I
>          4: sipush        200
>          7: if_icmpne     18
>
> In other words, the SpHttpStatus.SC_OK constant has been inlined and
> replaced
> with its value. However, that constant is defined in a different module
> than
> the calling code, meaning that if at runtime, a version with a different
> value
> is used, things will break. I didn't expect that (I was expecting late
> binding) - does anyone on this list know something about the rationale for
> this?
>
> Another question, probably more suitable for this mailing list: The
> problem I
> am trying to solve is to automatically trim/correct inter-project
> dependencies
> by looking into the bytecode of the classes to see which external classes
> are
> actually referenced. This particular thing makes it hard for me to extract
> the
> fact that this code references the SpHttpStatus class. That fact is noted
> in
> the constant pool, but I don't see an easy way of accessing that
> information -
> is there a good way to do that?
>
> Thanks,
> Petter
>
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