26 April 2013

Runtime Source Dependencies and Linux Runtime Include bug fix

The latest code on Github includes a new feature - Runtime Source Dependencies - along with a bugfix for Linux builds which resolves an issue with Runtime Includes.

A runtime source dependency is a source file which you need to have compiled when a given header is included by a runtime modifiable source file. Whilst having the source in a library and using the Runtime Link Library feature solves this problem to an extent, sometimes you don't want to create a whole library and thus the ability to compile in dependencies is a really useful feature. Using this feature simply requires the following lines in a header:

#include "RuntimeSourceDependency.h"
RUNTIME_COMPILER_SOURCEDEPENENCY;

If the header is called SomeFeature.h then the source file SomeFeature.cpp is compiled when any runtime modifiable code is changed which includes this header. Using the same filename as the header is required at the moment, in part due to issues with getting full paths from builds on Linux with GCC.

This brings us to the bug fix on Linux - although we'd implemented a system to get the full path for runtime modified source files from GCC, this hadn't been implemented for runtime includes and making the above changes caught this bug, so it's now been fixed. GCC only embeds the path passed in for __FILE__, which can be a relative path from the compile location, so we have to embed the compile path using the pre-processor define COMPILE_PATH="$(PWD)/"; Note that this isn't required if your build system uses full paths, which the cmake builds do, as does the internal GCC runtime compiler.

Note that I'm experiencing an odd issue on my cmake builds on Linux with makefiles - the Eclipse generated files work well however the makefile ones compile but the SimpleTest program fails to create a glfw window.

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