Fix issue2183

[0xc0170]

@bogdanm @theotherjimmy Please review. This is a fix for backward compatibility as our tools use for instance if is in Exporter.TARGETS . I found one more solution to this via metaclass, but was less clear to me. Any suggestions welcome.

Tested with the same command as reported, plus some others (uvision4,5 and iar as all of them introduced TARGETS as property):
tools\project.py -c -m NUCLEO_L432KC -p 0 -i uvision5

cc @svastm

[svastm]

Looks ok to me but after a quick test,

class ExporterTargetsProperty(object):
    def __init__(self, func):
        self.func = func
    def __get__(self, inst, cls):
        print("[PROP] inst: " + str(inst) + ", cls: " + str(cls))
        return self.func(cls)

class ClassTest(object):
    @ExporterTargetsProperty
    def property_test(cls):
        print("[FUNC] cls: " + str(cls))
        return [1, 2, 3]

# Call from class
if 1 in ClassTest.property_test:
    print("OK")

# Call from instance    
instance_test = ClassTest()
if 1 in instance_test.property_test:
    print("OK")

[PROP] inst: None, cls: <class '__main__.ClassTest'>
[FUNC] cls: <class '__main__.ClassTest'>
OK
[PROP] inst: <__main__.ClassTest object at 0x025CD490>, cls: <class '__main__.ClassTest'>
[FUNC] cls: <class '__main__.ClassTest'>
OK

the TARGETS() take as parameter cls instead of self when called from instance and class.

To be more consistent, the method should be

@ExporterTargetsProperty
def TARGETS(cls):
        if not hasattr(cls, "_TARGETS_SUPPORTED"):
            cls._TARGETS_SUPPORTED = []
            for target in TARGET_NAMES:
                try:
                    if (ProGenDef('iar').is_supported(str(TARGET_MAP[target])) or
                        ProGenDef('iar').is_supported(TARGET_MAP[target].progen['target'])):
                        cls._TARGETS_SUPPORTED.append(target)
                except AttributeError:
                    # target is not supported yet
                    continue
        return cls._TARGETS_SUPPORTED

[0xc0170]

@svastm cls shall be used for a class method (reason: PEP 8). I don't think @property is. When you look at python examples (this one is for python 3) https://docs.python.org/3/library/functions.html#property, @property has self as an argument there as well.

[svastm]

@property don't but @ExporterTargetsProperty call func on <class '__main__.ClassTest'> and not on <__main__.ClassTest object at 0x0251D510>. So a method decorated by @ExporterTargetsProperty can be called class method.

[0xc0170]

@svastm Updated ;)

[bogdanm]

LGTM. It looks like it fixes the reported issue, so it's good to go.