RF: delay calls of array repr in getlimits

Delay use of array repr until needed for string representations of the
float info parameters.  This is to allow getlimits to be imported early
without pulling in too much of the repr machinery.

See: numpy#8983 (comment)

numpy/core/getlimits.py

@@ -68,7 +68,8 @@ def __init__(self,
         params = _MACHAR_PARAMS[ftype]
         float_conv = lambda v: array([v], ftype)
         float_to_float = lambda v : _fr1(float_conv(v))
-        float_to_str = lambda v: (params['fmt'] % array(_fr0(v)[0], ftype))
+        self._float_to_str = lambda v: (params['fmt'] %
+                                        array(_fr0(v)[0], ftype))
         self.title = params['title']
         # Parameter types same as for discovered MachAr object.
         self.epsilon = self.eps = float_to_float(kwargs.pop('eps'))
@@ -79,11 +80,30 @@ def __init__(self,
         self.__dict__.update(kwargs)
         self.precision = int(-log10(self.eps))
         self.resolution = float_to_float(float_conv(10) ** (-self.precision))
-        self._str_eps = float_to_str(self.eps)
-        self._str_epsneg = float_to_str(self.epsneg)
-        self._str_xmin = float_to_str(self.xmin)
-        self._str_xmax = float_to_str(self.xmax)
-        self._str_resolution = float_to_str(self.resolution)
+
+    # Properties below to delay need for float_to_str, and thus avoid circular
+    # imports during early numpy module loading.
+    # See: https://github.com/numpy/numpy/pull/8983#discussion_r115838683
+
+    @property
+    def _str_eps(self):
+        return self._float_to_str(self.eps)
+
+    @property
+    def _str_epsneg(self):
+        return self._float_to_str(self.epsneg)
+
+    @property
+    def _str_xmin(self):
+        return self._float_to_str(self.xmin)
+
+    @property
+    def _str_xmax(self):
+        return self._float_to_str(self.xmax)
+
+    @property
+    def _str_resolution(self):
+        return self._float_to_str(self.resolution)
 
 
 # Known parameters for float16