Add float initializer to FtPrecise

freqtrade/exchange/exchange.py

@@ -709,8 +709,8 @@ class Exchange:
             #                                    counting_mode=self.precisionMode,
             #                                    ))
             if self.precisionMode == TICK_SIZE:
-                precision = FtPrecise(str(self.markets[pair]['precision']['price']))
-                price_str = FtPrecise(str(price))
+                precision = FtPrecise(self.markets[pair]['precision']['price'])
+                price_str = FtPrecise(price)
                 missing = price_str % precision
                 if not missing == FtPrecise("0"):
                     price = round(float(str(price_str - missing + precision)), 14)

freqtrade/util/ft_precise.py

@@ -1,9 +1,12 @@
 """
 Slim wrapper around ccxt's Precise (string math)
-To have imports from freqtrade
+To have imports from freqtrade - and support float initializers
 """
 from ccxt import Precise
 
 
 class FtPrecise(Precise):
-    pass
+    def __init__(self, number, decimals=None):
+        if not isinstance(number, str):
+            number = str(number)
+        super().__init__(number, decimals)

tests/exchange/test_ccxt_precise.py

@@ -73,3 +73,8 @@ def test_FtPrecise():
 
     assert FtPrecise('3.1415') <= FtPrecise('3.1415')
     assert FtPrecise('3.1415') <= FtPrecise('3.14150000000000000000001')
+
+    assert FtPrecise(213) == '213'
+    assert FtPrecise(-213) == '-213'
+    assert str(FtPrecise(-213)) == '-213'
+    assert FtPrecise(213.2) == '213.2'