[roslaunch] roslaunch-check doesn't respect if/unless

[mikepurvis]

We're having a case where we have some launch files which optionally include other launch files based on an environment variable being set. These are failing the test created by roslaunch_add_file_check, since it doesn't respect the conditional and attempts to resolve all include elements without regard for context.

This can be reproduced trivially by a launch file such as this, which launches just fine, but will (wrongly, in my opinion) fail the roslaunch check:

<launch>
  <include if="0" file="does/not/exist.launch" />
</launch>

---

Interestingly, roslaunch_add_file_check totally does resolve $(arg), $(env), $(optenv), etc, so this really does seem to be an issue with just the conditionals.

[mikepurvis]

I believe the issue is here:

ros_comm/tools/roslaunch/src/roslaunch/depends.py

Lines 144 to 148 in 6742631

	elif tag.tagName == 'include':
	try:
	sub_launch_file = resolve_args(tag.attributes['file'].value, context)
	except KeyError as e:
	raise RoslaunchDepsException("Cannot load roslaunch <%s> tag: missing required attribute %s.\nXML is %s"%(tag.tagName, str(e), tag.toxml()))

It needs logic to explicitly check for if/unless, similar to how the args work:

ros_comm/tools/roslaunch/src/roslaunch/depends.py

Lines 99 to 106 in 6742631

	if tag.attributes.has_key('if'):
	val = resolve_args(tag.attributes['if'].value, context)
	if val == '1' or val == 'true':
	return (name, _get_arg_value(tag, context))
	elif tag.attributes.has_key('unless'):
	val = resolve_args(tag.attributes['unless'].value, context)
	if val == '0' or val == 'false':
	return (name, _get_arg_value(tag, context))

What's mysterious to me is that this works correctly for a normal launch but not for roslaunch-check. Is there some preprocessing going on that strips out tags based on if/unless attributes?

---

Looks like for a normal launch, this is handled by xmlloader.py, and the @ifunless decorator:

ros_comm/tools/roslaunch/src/roslaunch/xmlloader.py

Lines 69 to 96 in caab9fd

	def ifunless_test(obj, tag, context):
	"""
	@return True: if tag should be processed according to its if/unless attributes
	"""
	if_val, unless_val = obj.opt_attrs(tag, context, ['if', 'unless'])
	if if_val is not None and unless_val is not None:
	raise XmlParseException("cannot set both 'if' and 'unless' on the same tag")
	if if_val is not None:
	if_val = loader.convert_value(if_val, 'bool')
	if if_val:
	return True
	elif unless_val is not None:
	unless_val = loader.convert_value(unless_val, 'bool')
	if not unless_val:
	return True
	else:
	return True
	return False
	def ifunless(f):
	"""
	Decorator for evaluating whether or not tag function should run based on if/unless attributes
	"""
	def call(*args, **kwds):
	#TODO: logging, as well as check for verbose in kwds
	if ifunless_test(args[0], args[1], args[2]):
	return f(*args, **kwds)
	return call

@dirk-thomas It seems like there are some parallel implementation issues going on here, but I don't have the desire or energy to do a wholesale fixup of it. I'd prefer to fix the immediate bug as best I can and at least add a unit test which would help support a future refactoring. Unless you have some particular insight into what the relationship is between xmlloader and these other pieces?

[dirk-thomas]

Addressed by #998. Thank you!