More Noob Friendly Intro about ycm-generator

[rdnetto]

Ok, so there's two separate things here I'd like to talk about:

The first is that the core idea is not that you should write makefiles, etc. with YCM-Gen in mind - it's that you should just write good, portable makefiles and YCM-Gen will just work. Actually, all portable means for us is that you haven't hardcoded the path to the compiler. That is, you should be using $(CC) and $(CXX) instead of the name of the compiler.

The second is that the large projects aren't there as examples of how a build system should be written. They're there to demonstrate that YCM-Gen works with 'real' projects, with all their painful complexity and ugly hacks.

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That being said, it probably is worthwhile to include an example, so here's the Makefile from a simple C program I wrote a little while ago as reference, which I consider to be fairly concise:

CFLAGS=-g -std=gnu99 -Wall -Wno-parentheses

all: main.o base_station.o sensor_node.o
    $(CC) $(CFLAGS) $^ -o simulate_wsn

clean:
    rm -rf *.o simulate_wsn

main.c, base_station.c, etc. are the source files. (Header files do not need to be included.) Because their respective object files are dependencies of all, make will generate implicit targets for them of the form:

$(CC) $(CFLAGS) foo.c -o foo.o

We then have a single explicitly defined rule for the all target, which links those object files together to generate the binary. ($^ contains all the dependencies of the current target. i.e. the object file names). The clean target is needed as YCM-Gen uses it to erase any state left behind, but you'll normally want to include that anyway out of convenience.

It's worth noting that you can ignore pretty much all of what I said, because only two things really matter:

• there should be all and clean targets
• all invocations of the C compiler use $(CC) instead of gcc, etc. (Use $(CXX) for C++.)

Now, if for some reason you need to use a specific / non-default compiler for a given project, you can define the CC variable (in a similar fashion to the CFLAGS variable), but you will then need to pass --make-flags=-e to YCM-Gen so that it will be overridden.

Let me know if I've left anything out. :)