Mix Shared and Static Libraries to Reduce Bloat?

[matt.mccormick]

@spinicist

My repo is here: GitHub - spinicist/QUIT: A set of tools for processing Quantitative MR Images.

This is very cool!

@spinicist

I tried building ITK as static libraries, tried to link those into my shared library, and then link my executables against the shared library. This led to utterly bizarre behaviour from one of my custom filters where accessing each output would cause the filter to re-update itself unnecessarily, and from the output it looked like multiple instances of the filter came into existence.

This is a consequence of how static libraries work and how global variables are handled. For now, if mixing static libraries and shared libraries, link the static library into the executable / shared libraries only once. This is a general rule of thumb that is relevant to most static libraries. Linking the static library into multiple shared libraries or a shared library will cause issues. We are working a way mitigate these issues in ITK, but it would still require explicit action to call the relevant methods in applications that want to build this way.