nmigen/_unused.py

   1 import sys
   2 import warnings
   3
   4 from ._utils import get_linter_option
   5
   6
   7 __all__ = ["UnusedMustUse", "MustUse"]
   8
   9
  10 class UnusedMustUse(Warning):
  11     pass
  12
  13
  14 class MustUse:
  15     _MustUse__silence = False
  16     _MustUse__warning = UnusedMustUse
  17
  18     def __new__(cls, *args, src_loc_at=0, **kwargs):
  19         frame = sys._getframe(1 + src_loc_at)
  20         self = super().__new__(cls)
  21         self._MustUse__used    = False
  22         self._MustUse__context = dict(
  23             filename=frame.f_code.co_filename,
  24             lineno=frame.f_lineno,
  25             source=self)
  26         return self
  27
  28     def __del__(self):
  29         if self._MustUse__silence:
  30             return
  31         if hasattr(self, "_MustUse__used") and not self._MustUse__used:
  32             if get_linter_option(self._MustUse__context["filename"],
  33                                  self._MustUse__warning.__name__, bool, True):
  34                 warnings.warn_explicit(
  35                     "{!r} created but never used".format(self), self._MustUse__warning,
  36                     **self._MustUse__context)
  37
  38
  39 _old_excepthook = sys.excepthook
  40 def _silence_elaboratable(type, value, traceback):
  41     # Don't show anything if the interpreter crashed; that'd just obscure the exception
  42     # traceback instead of helping.
  43     MustUse._MustUse__silence = True
  44     _old_excepthook(type, value, traceback)
  45 sys.excepthook = _silence_elaboratable