def __repr__(self):
        return "<NamedRequirements({}{})>".format(
            self.name,
            ", filename='{}'".format(self.filename.name) if self.filename
            else "")
def foam_arch(self):
        if not self._foam_arch:
            self._foam_arch = OpenfoamOrgArch(self.spec, **self.config)
        return self._foam_arch