We've already been introduced to the
COMMAND_LINE_TARGETS variable,
which contains a list of targets specified on the command line,
and the DEFAULT_TARGETS variable,
which contains a list of targets specified
via calls to the Default method or function.
Sometimes, however,
you want a list of whatever targets
SCons will try to build,
regardless of whether the targets came from the
command line or a Default call.
You could code this up by hand, as follows:
if COMMAND_LINE_TARGETS:
targets = COMMAND_LINE_TARGETS
else:
targets = DEFAULT_TARGETS
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SCons, however, provides a convenient
BUILD_TARGETS variable
that eliminates the need for this by-hand manipulation.
Essentially, the BUILD_TARGETS variable
contains a list of the command-line targets,
if any were specified,
and if no command-line targets were specified,
it contains a list of the targets specified
via the Default method or function.
Because BUILD_TARGETS may contain a list of SCons nodes,
you must convert the list elements to strings
if you want to print them or look for a specific target name,
just like the DEFAULT_TARGETS list:
prog1 = Program('prog1.c')
Program('prog2.c')
Default(prog1)
print "BUILD_TARGETS is", map(str, BUILD_TARGETS)
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Notice how the value of BUILD_TARGETS
changes depending on whether a target is
specified on the command line:
% scons -Q
BUILD_TARGETS is ['prog1']
cc -o prog1.o -c prog1.c
cc -o prog1 prog1.o
% scons -Q prog2
BUILD_TARGETS is ['prog2']
cc -o prog2.o -c prog2.c
cc -o prog2 prog2.o
% scons -Q -c .
BUILD_TARGETS is ['.']
Removed prog1.o
Removed prog1
Removed prog2.o
Removed prog2
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