How do I use libraries manually?

[H. S. Teoh]

On Tue, Feb 05, 2019 at 07:06:24PM +0000, Murilo via Digitalmars-d-learn wrote:
> Can anyone teach me how to download and use a library manually without
> having to use DUB?

1) Locate the source code. There should be a link from the
   code.dlang.org page of the library, usually pointing to github.com or
   some similar public repo hosting service, or pointing to a .zip or a
   tarball that you can download.

2) Download the source code.  If it's from github.com, `git clone
   <download URL>` should create the source directory.  If it's a zip
   file or a tarball, you'll need to download and uncompress it
   yourself.

3) Identify the import directory (directories).  For simplicity, Let's
   assume you placed the downloaded sources in /path/to/somelibrary/ (or
   if you're on Windows, C:\path\to\somelibrary\).  If the library is a
   DUB package, the code should usually be under "source", i.e.,
   /path/to/somelibrary/source or C:\path\to\somelibrary\source. For
   complex libraries, there may be more than one such path that you'll
   need.

4) Repeat the above step for all dependencies of the library.

	# Example
	git clone http://github.com/somelibrary.git /path/to/somelibrary
	git clone http://github.com/anotherlibrary.git /path/to/anotherlibrary

5) Once you've identified all needed import paths, add the import
   directories to your dmd command line with -I, one for each import
   directory. Using the above example, you'll need something like this:

   	dmd -I/path/to/somelibrary/source ...

   Or, if there's more than one import directory:

   	dmd -I/path/to/somelibrary/source -I/path/to/anotherlibrary/source ...

6) Add -i to your dmd command line so that it will automatically compile
   any imports that you use. This requires a pretty up-to-date version
   of dmd.
   
   If this fails, you'll have to manually compile each library and its
   dependencies.  Start with the dependencies first, then the dependent
   library, then finally your program.  You'll probably need to specify
   -lib for most of your library dependencies so that dmd produces .so
   or .a (or .lib) files that you'll need. You may need separate
   compilation if the library is too big to compile all at once.

   When linking the library, you'll need to specify any dependent
   library .so or .a (.lib) files.


For example, let's say somelibrary depends on anotherlibrary.  For
simplicity, let's assume all their sources lie in the respective
`source` subdirectory. So you have:

	/path/to/somelibrary/source/*.d
	/path/to/anotherlibrary/source/*.d

So the first step is to compile anotherlibrary (because somelibrary
depends on it, and may not compile if it's anotherlibrary isn't compiled
first), then compile the rest.

	cd /path/to/anotherlibrary
	dmd -lib -o libanotherlibrary.a -Isource source/*.d

	# Assuming the preceding was successful
	cd /path/to/somelibrary
	dmd -lib -o somelibrary.a -Isource -I/path/to/anotherlibrary/source \
		source/*.d /path/to/anotherlibrary/libanotherlibrary.a

	# Finally, compile your own program
	cd /path/to/myprogram
	dmd -o myprogram -Isource -I/path/to/anotherlibrary/source \
		-I/path/to/somelibrary/source source/*.d \
		/path/to/anotherlibrary/libanotherlibrary.a \
		/path/to/somelibrary/libsomelibrary.a

You'll probably want to put these commands in a shell script / batch
file, since the commands can get pretty long and complicated and
error-prone, and you really don't want to have to retype everything by
hand just to fix a small typo in the middle.  Or put this in a makefile
or build script of your build system of choice.

Note that for each step, you may need additional flags to dmd to compile
a dependency; consult the dub.sdl / dub.json file to find any that might
be necessary.

Welcome to the world of manual compilation. :-D  (This is where you
start to really appreciate things like Adam Ruppe's single-file library
modules, where you can just copy the file into your source tree and
include it in your dmd command line without needing to go through the
above baroque dance.)


T

-- 
Without geometry, life would be pointless. -- VS