suyu/externals/vcpkg/packages/boost-build_x64-windows/tools/boost-build/example/variant/readme.qbk

[/
Copyright 2004 Vladimir Prus
Copyright 2017 Rene Rivera
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
/]

[section Build Variants]

This example shows how user can create his own build variants. Two variants are
defined: "crazy", which is just a random combination of properties, and
"super-release", which is inherited from "release", and differs by a single
define.

Files:

* [@../../example/variant/a.cpp a.cpp]
* [@../../example/variant/jamroot.jam jamroot.jam]
* [@../../example/variant/jamfile.jam jamfile.jam]
* [@../../example/variant/libs/jamfile.jam libs/jamfile.jam]
* [@../../example/variant/libs/l.cpp libs/l.cpp]

[import jamroot.jam]
[import jamfile.jam]
[import libs/jamfile.jam]

In this project the `jamroot.jam` specifies the custom build variants and the
targets are specified in the two `jamfile.jam` files.

[jamroot]

The top-level `jamfile.jam`:

[jamfile]

And the library `jamfile.jam` that the top-level `jamfile.jam` refers to:

[libs_jamfile]

Building the example yields:

[teletype]
```
> cd /example/variant
> b2
...found 20 targets...
...updating 16 targets...
common.mkdir bin
common.mkdir bin/clang-darwin-4.2.1
common.mkdir bin/clang-darwin-4.2.1/crazy
clang-darwin.compile.c++ bin/clang-darwin-4.2.1/crazy/a.o
common.mkdir libs/bin
common.mkdir libs/bin/clang-darwin-4.2.1
common.mkdir libs/bin/clang-darwin-4.2.1/crazy
clang-darwin.compile.c++ libs/bin/clang-darwin-4.2.1/crazy/l.o
clang-darwin.link.dll libs/bin/clang-darwin-4.2.1/crazy/libl.dylib
clang-darwin.link bin/clang-darwin-4.2.1/crazy/a
common.mkdir bin/clang-darwin-4.2.1/super_release
clang-darwin.compile.c++ bin/clang-darwin-4.2.1/super_release/a.o
common.mkdir libs/bin/clang-darwin-4.2.1/super_release
clang-darwin.compile.c++ libs/bin/clang-darwin-4.2.1/super_release/l.o
clang-darwin.link.dll libs/bin/clang-darwin-4.2.1/super_release/libl.dylib
clang-darwin.link bin/clang-darwin-4.2.1/super_release/a
...updated 16 targets...
```

As specified in the top-level `jamfile.jam` both custom variants where built
by default. Once can override that by specifying the variant one wants to
build directly on the command line with a `variant=super_release`. Or just
with a `super_release` as variants can be referred to by their name only.
For example using that argument yields:

```
> cd /example/variant
> b2 super_release
...found 14 targets...
...updating 10 targets...
common.mkdir bin
common.mkdir bin/clang-darwin-4.2.1
common.mkdir bin/clang-darwin-4.2.1/super_release
clang-darwin.compile.c++ bin/clang-darwin-4.2.1/super_release/a.o
common.mkdir libs/bin
common.mkdir libs/bin/clang-darwin-4.2.1
common.mkdir libs/bin/clang-darwin-4.2.1/super_release
clang-darwin.compile.c++ libs/bin/clang-darwin-4.2.1/super_release/l.o
clang-darwin.link.dll libs/bin/clang-darwin-4.2.1/super_release/libl.dylib
clang-darwin.link bin/clang-darwin-4.2.1/super_release/a
...updated 10 targets...
```

[note The actual paths in the `bin` sub-directory will depend on your
toolset.]

[endsect]