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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:

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

1variant crazy : <optimization>speed <inlining>off
                <debug-symbols>on <profiling>on ;

2variant super_release : release : <define>USE_ASM ;

1

Define a build variant which is just combination of four properties.

2

Define a built variant inherited from 'release'. It defines one new property and gets all properties from the parent release variant.

The top-level jamfile.jam: 

1project : default-build crazy super_release ;

2exe a : a.cpp libs//l ;

1

By default, build the project with the two variants we have defined in jamroot.jam.

2

We build an a exe target that links a built library. The library builds with the propagated properties of the exe.

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

1lib l : l.cpp ;

1

The library l just needs the sources. By default it will be a shared library.

Building the example yields: 

> 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.

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