Package SCons :: Module Taskmaster :: Class Task
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Class Task

source code

Known Subclasses:
SConf.SConfBuildTask, Script.Main.BuildTask, Script.Main.CleanTask, Script.Main.QuestionTask


Default SCons build engine task.

This controls the interaction of the actual building of node
and the rest of the engine.

This is expected to handle all of the normally-customizable
aspects of controlling a build, so any given application
*should* be able to do what it wants by sub-classing this
class and overriding methods as appropriate.  If an application
needs to customze something by sub-classing Taskmaster (or
some other build engine class), we should first try to migrate
that functionality into this class.

Note that it's generally a good idea for sub-classes to call
these methods explicitly to update state, etc., rather than
roll their own interaction with Taskmaster from scratch.



Instance Methods [hide private]
 
__init__(self, tm, targets, top, node) source code
 
trace_message(self, method, node, description='node') source code
 
display(self, message)
Hook to allow the calling interface to display a message.
source code
 
prepare(self)
Called just before the task is executed.
source code
 
get_target(self)
Fetch the target being built or updated by this task.
source code
 
needs_execute(self)
Called to determine whether the task's execute() method should be run.
source code
 
execute(self)
Called to execute the task.
source code
 
executed_without_callbacks(self)
Called when the task has been successfully executed and the Taskmaster instance doesn't want to call the Node's callback methods.
source code
 
executed_with_callbacks(self)
Called when the task has been successfully executed and the Taskmaster instance wants to call the Node's callback methods.
source code
 
executed(self)
Called when the task has been successfully executed and the Taskmaster instance wants to call the Node's callback methods.
source code
 
failed(self)
Default action when a task fails: stop the build.
source code
 
fail_stop(self)
Explicit stop-the-build failure.
source code
 
fail_continue(self)
Explicit continue-the-build failure.
source code
 
make_ready_all(self)
Marks all targets in a task ready for execution.
source code
 
make_ready_current(self)
Marks all targets in a task ready for execution if any target is not current.
source code
 
make_ready(self)
Marks all targets in a task ready for execution if any target is not current.
source code
 
postprocess(self)
Post-processes a task after it's been executed.
source code
 
exc_info(self)
Returns info about a recorded exception.
source code
 
exc_clear(self)
Clears any recorded exception.
source code
 
exception_set(self, exception=False)
Records an exception to be raised at the appropriate time.
source code
 
_no_exception_to_raise(self) source code
 
_exception_raise(self)
Raises a pending exception that was recorded while getting a Task ready for execution.
source code
Method Details [hide private]

display(self, message)

source code 

Hook to allow the calling interface to display a message.

This hook gets called as part of preparing a task for execution
(that is, a Node to be built).  As part of figuring out what Node
should be built next, the actually target list may be altered,
along with a message describing the alteration.  The calling
interface can subclass Task and provide a concrete implementation
of this method to see those messages.

prepare(self)

source code 

Called just before the task is executed.

This is mainly intended to give the target Nodes a chance to
unlink underlying files and make all necessary directories before
the Action is actually called to build the targets.

needs_execute(self)

source code 

Called to determine whether the task's execute() method should
be run.

This method allows one to skip the somethat costly execution
of the execute() method in a seperate thread. For example,
that would be unnecessary for up-to-date targets.

execute(self)

source code 

Called to execute the task.

This method is called from multiple threads in a parallel build,
so only do thread safe stuff here.  Do thread unsafe stuff in
prepare(), executed() or failed().

executed_with_callbacks(self)

source code 

Called when the task has been successfully executed and
the Taskmaster instance wants to call the Node's callback
methods.

This may have been a do-nothing operation (to preserve build
order), so we must check the node's state before deciding whether
it was "built", in which case we call the appropriate Node method.
In any event, we always call "visited()", which will handle any
post-visit actions that must take place regardless of whether
or not the target was an actual built target or a source Node.

executed(self)

source code 

Called when the task has been successfully executed and
the Taskmaster instance wants to call the Node's callback
methods.

This may have been a do-nothing operation (to preserve build
order), so we must check the node's state before deciding whether
it was "built", in which case we call the appropriate Node method.
In any event, we always call "visited()", which will handle any
post-visit actions that must take place regardless of whether
or not the target was an actual built target or a source Node.

failed(self)

source code 

Default action when a task fails:  stop the build.

Note: Although this function is normally invoked on nodes in
the executing state, it might also be invoked on up-to-date
nodes when using Configure().

fail_stop(self)

source code 

Explicit stop-the-build failure.

This sets failure status on the target nodes and all of
their dependent parent nodes.

Note: Although this function is normally invoked on nodes in
the executing state, it might also be invoked on up-to-date
nodes when using Configure().

fail_continue(self)

source code 

Explicit continue-the-build failure.

This sets failure status on the target nodes and all of
their dependent parent nodes.

Note: Although this function is normally invoked on nodes in
the executing state, it might also be invoked on up-to-date
nodes when using Configure().

make_ready_all(self)

source code 

Marks all targets in a task ready for execution.

This is used when the interface needs every target Node to be
visited--the canonical example being the "scons -c" option.

make_ready_current(self)

source code 

Marks all targets in a task ready for execution if any target
is not current.

This is the default behavior for building only what's necessary.

make_ready(self)

source code 

Marks all targets in a task ready for execution if any target
is not current.

This is the default behavior for building only what's necessary.

postprocess(self)

source code 

Post-processes a task after it's been executed.

This examines all the targets just built (or not, we don't care
if the build was successful, or even if there was no build
because everything was up-to-date) to see if they have any
waiting parent Nodes, or Nodes waiting on a common side effect,
that can be put back on the candidates list.

exc_clear(self)

source code 

Clears any recorded exception.

This also changes the "exception_raise" attribute to point
to the appropriate do-nothing method.

exception_set(self, exception=False)

source code 

Records an exception to be raised at the appropriate time.

This also changes the "exception_raise" attribute to point
to the method that will, in fact