pd-lib-builder cheatsheet
=========================

# Creating special builds

## cross-compiling on linux for other platforms and architectures

Using pd-lib-builder >=0.6.0 we can define variable `PLATFORM` to specify a 
target triplet for cross-compilation. Example to build W32 binaries (assuming 
package `mingw-w64` is installed and a W32 package for Pd is unzipped into a 
path `${PDWIN32}`:

    make PLATFORM=x86_64-w64-mingw32 PDDIR="${PDWIN32}"

#### older pd-lib-builder versions

Using pd-lib-builder < 0.6.0, in the absence of variable `PLATFORM`, you would
instead override variables `system`, `target.arch`, `CC` and / or `CXX`,
`STRIP`. Example:

    make system=Windows target.arch=i686 CC=i686-w64-mingw32-gcc STRIP=i686-w64-mingw32-strip PDDIR="${PDWIN32}"

#### toolchains

Cross toolchains for relevant platforms in Debian Buster (install g++ 
with dependencies for a given platform to get the whole tool chain):

- `arm-linux-gnueabihf`
- `aarch64-linux-gnu`
- `i686-linux-gnu`
- `i686-w64-mingw32` and `x86_64-w64-mingw32` (install `mingw-w64`)

OSX/MacOS cross tool chains are not distributed by Debian. Use project 
`osxcross` from Thomas Poechtraeger to create the tools.

## building double-precision externals

At the time of writing (2018-02) there is no official Pd that supports
double-precision numbers yet.
However, if you do get hold of an experimental double-precision Pd, you can
easily build your externals for 64-bit numbers:

   make CPPFLAGS="-DPD_FLOATSIZE=64"

## building externals for W64 (64-bit Windows)

At the time of writing (2018-02) there is no official Pd that supports
W64 yet.
However, if you do get hold of an experimental W64 Pd, you can
easily build your externals for this environment with

   make CPPFLAGS="-DPD_LONGINTTYPE=__int64" CC=x86_64-w64-mingw32-gcc


To build a double-precision external for W64, use something like:

   make CPPFLAGS="-DPD_LONGINTTYPE=__int64 -DPD_FLOATSIZE=64" CC=x86_64-w64-mingw32-gcc


## TODO universal binaries on OSX


# Project management

In general it is advised to put the `Makefile.pdlibbuilder` into a separate
subdirectory (e.g. `pd-lib-builder/`).
This makes it much easier to update the `Makefile.pdlibbuilder` later

You *should* also use a variable to the actual path of the Makefile.pdlibbuilder
(even if you keep it in the root-directory), as this allows easy experimenting
with newer (or older) (or site-specific) versions of the pd-lib-builder
Makefile.

~~~make
PDLIBBUILDER_DIR=pd-lib-builder/
include $(PDLIBBUILDER_DIR)/Makefile.pdlibbuilder
~~~

## Keeping pd-lib-builder up-to-date

### `git subtree`

With git-subtrees, you make the pd-lib-builder repository (or any other
repository for that matter) part of your own repository - with full history and
everything - put nicely into a distinct subdirectory.

Support for *manipulating* subtrees has been added with Git-v1.7.11 (May 2012).
The nice thing however is, that from "outside" the subtree is part of your
repository like any other directory. E.g. older versions of Git can clone your
repository with the full subtree (and all it's history) just fine.
You can also use git-archive to make a complete snapshot of your repository
(including the subtree) - nice, if you e.g. want self-contained downloads of
your project from git hosting platforms (like Github, Gitlab, Bitbucket,...)

In short, `git subtree` is the better `git submodule`.

So here's how to do it:

#### Initial setup/check-out
This will create a `pd-lib-builder/` directory containing the full history of
the pd-lib-builder repository up to its release `v0.5.0`

~~~sh
git subtree add --prefix=pd-lib-builder/ https://github.com/pure-data/pd-lib-builder v0.5.0
~~~

This will automatically merge the `pd-lib-builder/` history into your current
branch, so everything is ready to go.

#### Cloning your repository with the subtree
Nothing special, really.
Just clone your repository as always:

~~~sh
git clone https://git.example.org/pd/superbonk~.git
~~~

#### Updating the subtree
Time passes and sooner or later you will find, that there is a shiny new
pd-lib-builder with plenty of bugfixes and new features.
To update your local copy to pd-lib-builder's current `master`, simply run:

~~~sh
git subtree pull --prefix pd-lib-builder/ https://github.com/pure-data/pd-lib-builder master
~~~

#### Pulling the updated subtree into existing clones
Again, nothing special.
Just pull as always:

~~~sh
git pull
~~~


#### Further reading
More on the power of `git subtree` can be found online
- https://medium.com/@v/git-subtrees-a-tutorial-6ff568381844
- https://www.atlassian.com/blog/git/alternatives-to-git-submodule-git-subtree
- ...

### ~~`git submodule`~~ [DISCOURAGED]


#### Initial setup/check-out
To add a new submodule to your repository, just run `git submodule add` and
commit the changes:

~~~sh
git submodule add https://github.com/pure-data/pd-lib-builder
git commit .gitmodules pd-lib-builder/ -m "Added pd-lib-builder as git-submodule"
~~~

#### Cloning your repository with the submodule

When doing a fresh clone of your repository, pass the `--recursive` option to
automatically fetch all submodules:

~~~sh
git clone --recursive https://git.example.org/pd/superbonk~.git
~~~

If you've cloned non-recursively, you can initialize and update the submodules
manually:

~~~sh
git submodule init
git submodule update
~~~

#### Updating the submodule
Submodules are usually fixed to a given commit in their repository.
To update the `pd-lib-builder` submodule to the current `master` do something
like:

~~~sh
cd pd-lib-builder
git checkout master
git pull
cd ..
git status pd-lib-builder
git commit pd-lib-builder -m "Updated pd-lib-builder to current master"
~~~

#### Pulling the updated submodule into existing clones
After you have pushed the submodule updates in your repository, other clones of
the repository can be updated as follows:

~~~sh
git pull
~~~

The above will make your repository aware, that the submodule is out-of-sync.

~~~sh
$ LANG=C git status pd-lib-builder
On branch master
Your branch is up to date with 'origin/master'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

	modified:   pd-lib-builder (new commits)
$
~~~

In order to sync the submodule to the correct commit, run the following:

~~~sh
git submodule update
~~~

#### Drawbacks
`git submodule` has a number of drawbacks:
- it requires special commands to synchronize the submodules, in addition to
  synching your repository.
- you must make sure to use an URL for the submodule that is accessible to your
  potential users. e.g. using `git@github.com:pure-data/pd-lib-builder` is bad,
  because it requires everybody who wants to checkout your sources to have a
  github-account - even if they could checkout *your* repository anonymously.
- submodules will be excluded from `git archive`. This means, that if you use a
  mainstream git provider (like Github, GitLab, Bitbucket,...) and make releases
  by creating a `git tag`, the automatically generated zipfiles with the sources
  will lack the submodule - and your users will not be able to compile your
  source code.

In general, I would suggest to **avoid** `git submodule`, and instead use the
better `git subtree` (above).

