from test.support import TestFailed # A test for SF bug 422177: manifest float constants varied way too much in # precision depending on whether Python was loading a module for the first # time, or reloading it from a precompiled .pyc. The "expected" failure # mode is that when test_import imports this after all .pyc files have been # erased, it passes, but when test_import imports this from # double_const.pyc, it fails. This indicates a woeful loss of precision in # the marshal format for doubles. It's also possible that repr() doesn't # produce enough digits to get reasonable precision for this box. PI = 3.14159265358979324 TWOPI = 6.28318530717958648 PI_str = "3.14159265358979324" TWOPI_str = "6.28318530717958648" # Verify that the double x is within a few bits of eval(x_str). def check_ok(x, x_str): assert x > 0.0 x2 = eval(x_str) assert x2 > 0.0 diff = abs(x - x2) # If diff is no larger than 3 ULP (wrt x2), then diff/8 is no larger # than 0.375 ULP, so adding diff/8 to x2 should have no effect. if x2 + (diff / 8.) != x2: raise TestFailed("Manifest const %s lost too much precision " % x_str) check_ok(PI, PI_str) check_ok(TWOPI, TWOPI_str) SIMPAN PERUBAHAN