Call to DescriptorExtractor.create("SURF") causes NPE

[jpsacha]

Simple call to DescriptorExtractor.create("SURF") results in exception. Here is a sample code:

import org.bytedeco.javacpp.opencv_features2d.DescriptorExtractor;
new DescriptorExtractor().create("SURF");

Exception:

java.lang.NullPointerException: This pointer address is NULL.
    at org.bytedeco.javacpp.opencv_features2d$DescriptorExtractor.create(Native Method)
....

[saudet]

Binary snapshot released here:
https://oss.sonatype.org/content/repositories/snapshots/org/bytedeco/javacpp-presets/opencv/2.4.9-0.8-2-SNAPSHOT/
Thanks for reporting!

[jpsacha]

I cannot use the snapshot due to missing dependency:

javacpp-presets/opencv/pom.xml

Line 6 in 079d9b6

<parent>

<parent>
    <groupId>org.bytedeco</groupId>
    <artifactId>javacpp-presets</artifactId>
    <version>0.8-2-SNAPSHOT</version>
</parent>

It is missing in the snapshot repo:
https://oss.sonatype.org/content/repositories/snapshots/org/bytedeco/javacpp-presets/

[saudet]

Right, the binaries haven't changed, so we can hack something that way. Do
you have a better idea than making a complete release for every little bug?
It seems we can use this SNAPSHOT system for that, but it's clear to me yet
how exactly. Suggestions?

[jpsacha]

I can deal with dependencies of different version. Not a pretty setup but doable.
https://github.com/bytedeco/javacv-examples/blob/52ff65a0b58889b623bab525268d593f2a4817be/OpenCV2_Cookbook/build.sbt#L50

Here it is a bit different due to parent declaration. When I am trying to use artifact opencv it requires its parent according to what is in POM (artifact javacpp-presets). It is treated different than just a dependency. My suggestion is to release parent when children are released.

[saudet]

I see, the parent pom.xml file is missing! Of course, that's easy to do.
It's strange that Maven doesn't deploy that by default when called from the
parent. I'll do that when I get back home tomorrow. BTW, it should work
locally after a “mvn install -N“, IIRC.

[saudet]

Ok, I've uploaded the parent pom.xml file for 0.8-2-SNAPSHOT, so everything should work now!

[jpsacha]

I am testing this on windows. I am getting a strange error. SBT attempts to download platform snapshot as:
opencv-2.4.9-0.8-2-20140510.032943-13-windows-x86_64.jar
I am not clear why the SNAPSHOT is expanded that way rather than:
opencv-2.4.9-0.8-2-20140510.024254-7-windows-x86_64.jar

So I rebuild locally. Now DescriptorExtractor.create("SURF") works in Scala example but not in Java test (returns null), within the same project, but this is not related to this issue, maybe some classloader peculiarity.

[saudet]

I guess we need to figure out how to make the SNAPSHOT system work a bit better across Maven, SBT, and Gradle, hey. Let me know if you figure out how to fix any of that.

As for SURF, that's pretty normal. We need to call opencv_nonfree.initModule_nonfree(), but it seems to get called on load on most platforms anyway.

[saudet]

Do you know if SBT is complaining only about the buildNumber? Or something else? If it's only the buildNumber, there should be a way to force it. I'll look into that.

[saudet]

Good news, I've figured out how to make better SNAPSHOT "releases". Using the nexus-staging-maven-plugin, it's possible to stage locally before deploying remotely:
http://books.sonatype.com/nexus-book/reference/staging-sect-deployment.html
This way, everything gets the same build number. Please let me know if this still does not work well with SBT, thanks!

[jpsacha]

Are you planing to release new version (0.8.1?) so the release can be tested with SBT?

[saudet]

Are you saying SBT doesn't support SNAPSHOT versions?

[saudet]

I'm also trying to figure out a good way to manage versions across the artifacts, and create a parent pom.xml somehow, and there's issues with Gradle as well... If you have good ideas, let me know. I'd like to patch this up a bit better before making another release.

[jpsacha]

SBT does support snapshots. It is just not clear how you are asking me to test it. Did you released a SNAPSHOT that you want me to test?

[saudet]

Oh, l've just fixed the 0.8-2-SNAPSHOT builds. So, does it work OK that way
now?

[jpsacha]

It seems to work now with SBT and Cookbook Examples, I was able to re-download dependencies without building javacv*.
To be clear, I removed local cashes in ~/.m2 and ~/.ivy2 (used by SBT). Then rebuild current version of Cookbook examples (javacpp and javacpp-resets v.0.8-2-SNAPSHOT and javacv v.0.8). It was able to download needed dependencies automatically through SBT.

[saudet]

Fixed in version 0.9. Thanks for reporting!