From 7825a6021c460dbdbae36aea2d448481df301f46 Mon Sep 17 00:00:00 2001
From: The MMGen Project <mmgen@tuta.io>
Date: Wed, 20 May 2020 11:09:42 +0000
Subject: [PATCH] ImmutableAttr: move conversion logic from __set__() to
 __init__()

---
 mmgen/altcoins/eth/tw.py |  4 ++--
 mmgen/obj.py             | 46 ++++++++++++++++++++++++----------------
 mmgen/tw.py              |  4 ++--
 mmgen/tx.py              |  2 +-
 4 files changed, 33 insertions(+), 23 deletions(-)

diff --git a/mmgen/altcoins/eth/tw.py b/mmgen/altcoins/eth/tw.py
index 97dd80cd..ab5ab0fd 100755
--- a/mmgen/altcoins/eth/tw.py
+++ b/mmgen/altcoins/eth/tw.py
@@ -265,8 +265,8 @@ Actions:         [q]uit view, [p]rint to file, pager [v]iew, [w]ide view,
 	class MMGenTwUnspentOutput(MMGenListItem):
 		txid   = ListItemAttr('CoinTxID')
 		vout   = ListItemAttr(int,typeconv=False)
-		amt    = ImmutableAttr(lambda:g.proto.coin_amt,typeconv=False)
-		amt2   = ListItemAttr(lambda:g.proto.coin_amt,typeconv=False)
+		amt    = ImmutableAttr(lambda val:g.proto.coin_amt(val),typeconv=False)
+		amt2   = ListItemAttr(lambda val:g.proto.coin_amt(val),typeconv=False)
 		label  = ListItemAttr('TwComment',reassign_ok=True)
 		twmmid = ImmutableAttr('TwMMGenID')
 		addr   = ImmutableAttr('CoinAddr')
diff --git a/mmgen/obj.py b/mmgen/obj.py
index 46971382..61c55bef 100755
--- a/mmgen/obj.py
+++ b/mmgen/obj.py
@@ -231,10 +231,30 @@ class ImmutableAttr: # Descriptor
 	ok_dtypes = (str,type,type(None),type(lambda:0))
 
 	def __init__(self,dtype,typeconv=True,set_none_ok=False):
-		self.typeconv = typeconv
-		self.set_none_ok = set_none_ok
-		assert isinstance(dtype,self.ok_dtypes),'{!r}: invalid dtype arg'.format(dtype)
-		self.dtype = dtype
+		assert isinstance(dtype,self.ok_dtypes), 'ImmutableAttr_check1'
+		if set_none_ok:   assert typeconv and type(dtype) != str, 'ImmutableAttr_check3'
+
+		if type(dtype).__name__ == 'function':
+			self.conv = lambda instance,value: dtype(value)
+		elif typeconv:
+			"convert this attribute's type"
+			if type(dtype) == str:
+				self.conv = lambda instance,value: globals()[dtype](value,on_fail='raise')
+			else:
+				if set_none_ok:
+					self.conv = lambda instance,value: None if value is None else dtype(value)
+				else:
+					self.conv = lambda instance,value: dtype(value)
+		else:
+			"check this attribute's type"
+			def assign_with_check(instance,value):
+				if type(value) == dtype:
+					return value
+				raise TypeError('Attribute {!r} of {} instance must of type {}'.format(
+					self.name,
+					type(instance).__name__,
+					dtype ))
+			self.conv = assign_with_check
 
 	def __set_name__(self,owner,name):
 		self.name = name
@@ -248,22 +268,12 @@ class ImmutableAttr: # Descriptor
 
 	def __set__(self,instance,value):
 		if not self.setattr_condition(instance):
-			raise AttributeError('Attribute {self.name!r} of {type(instance)} instance cannot be reassigned')
-		if self.set_none_ok and value == None:
-			instance.__dict__[self.name] = None
-		elif self.typeconv:   # convert type
-			instance.__dict__[self.name] = \
-				globals()[self.dtype](value,on_fail='raise') if type(self.dtype) == str else self.dtype(value)
-		else:                 # check type
-			if type(value) == self.dtype:
-				instance.__dict__[self.name] = value
-			elif callable(self.dtype) and type(value) == self.dtype():
-				instance.__dict__[self.name] = value
-			else:
-				raise TypeError('Attribute {self.name!r} of {type(instance)} instance must of type {self.dtype}')
+			raise AttributeError(f'Attribute {self.name!r} of {type(instance)} instance cannot be reassigned')
+		instance.__dict__[self.name] = self.conv(instance,value)
 
 	def __delete__(self,instance):
-		raise AttributeError('Attribute {self.name!r} of {type(instance)} instance cannot be deleted')
+		raise AttributeError(
+			f'Attribute {self.name!r} of {type(instance).__name__} instance cannot be deleted')
 
 class ListItemAttr(ImmutableAttr):
 	"""
diff --git a/mmgen/tw.py b/mmgen/tw.py
index 24f416f0..f53877e8 100755
--- a/mmgen/tw.py
+++ b/mmgen/tw.py
@@ -87,8 +87,8 @@ Actions: [q]uit view, [p]rint to file, pager [v]iew, [w]ide view, add [l]abel:
 	class MMGenTwUnspentOutput(MMGenListItem):
 		txid         = ListItemAttr('CoinTxID')
 		vout         = ListItemAttr(int,typeconv=False)
-		amt          = ImmutableAttr(lambda:g.proto.coin_amt,typeconv=False)
-		amt2         = ListItemAttr(lambda:g.proto.coin_amt,typeconv=False)
+		amt          = ImmutableAttr(lambda val:g.proto.coin_amt(val),typeconv=False)
+		amt2         = ListItemAttr(lambda val:g.proto.coin_amt(val),typeconv=False)
 		label        = ListItemAttr('TwComment',reassign_ok=True)
 		twmmid       = ImmutableAttr('TwMMGenID')
 		addr         = ImmutableAttr('CoinAddr')
diff --git a/mmgen/tx.py b/mmgen/tx.py
index dc4fb117..67222fbb 100755
--- a/mmgen/tx.py
+++ b/mmgen/tx.py
@@ -223,7 +223,7 @@ class DeserializedTX(dict,MMGenObject):
 
 class MMGenTxIO(MMGenListItem):
 	vout     = ListItemAttr(int,typeconv=False)
-	amt      = ImmutableAttr(lambda:g.proto.coin_amt,typeconv=False)
+	amt      = ImmutableAttr(lambda val:g.proto.coin_amt(val),typeconv=False)
 	label    = ListItemAttr('TwComment',reassign_ok=True)
 	mmid     = ListItemAttr('MMGenID')
 	addr     = ImmutableAttr('CoinAddr')