diff --git a/mmgen/addr.py b/mmgen/addr.py
index ae76d698..0e5f6ac9 100755
--- a/mmgen/addr.py
+++ b/mmgen/addr.py
@@ -1159,7 +1159,7 @@ class TwAddrData(AddrData,metaclass=aInitMeta):
 		twd = await self.get_tw_data(wallet)
 		out,i = {},0
 		for acct,addr_array in twd:
-			l = TwLabel(self.proto,acct,on_fail='silent')
+			l = get_obj(TwLabel,proto=self.proto,text=acct,silent=True)
 			if l and l.mmid.type == 'mmgen':
 				obj = l.mmid.obj
 				if len(addr_array) != 1:
diff --git a/mmgen/altcoins/eth/tw.py b/mmgen/altcoins/eth/tw.py
index 7e05451f..8b21ee6d 100755
--- a/mmgen/altcoins/eth/tw.py
+++ b/mmgen/altcoins/eth/tw.py
@@ -257,7 +257,7 @@ Actions:         [q]uit view, [p]rint to file, pager [v]iew, [w]ide view,
 		if self.addrs:
 			wl = [d for d in wl if d['addr'] in self.addrs]
 		return [{
-				'account': TwLabel(self.proto,d['mmid']+' '+d['comment'],on_fail='raise'),
+				'account': TwLabel(self.proto,d['mmid']+' '+d['comment']),
 				'address': d['addr'],
 				'amount': await self.wallet.get_balance(d['addr']),
 				'confirmations': 0, # TODO
@@ -298,7 +298,7 @@ class EthereumTwAddrList(TwAddrList):
 		from mmgen.obj import CoinAddr
 		for mmid,d in list(tw_dict.items()):
 #			if d['confirmations'] < minconf: continue # cannot get confirmations for eth account
-			label = TwLabel(self.proto,mmid+' '+d['comment'],on_fail='raise')
+			label = TwLabel(self.proto,mmid+' '+d['comment'])
 			if usr_addr_list and (label.mmid not in usr_addr_list):
 				continue
 			bal = await self.wallet.get_balance(d['addr'])
diff --git a/mmgen/exception.py b/mmgen/exception.py
index 0d7d14cf..2dee1fa0 100755
--- a/mmgen/exception.py
+++ b/mmgen/exception.py
@@ -40,10 +40,11 @@ class InvalidTokenAddress(Exception):     mmcode = 2
 class UnrecognizedTokenSymbol(Exception): mmcode = 2
 class TokenNotInBlockchain(Exception):    mmcode = 2
 class TokenNotInWallet(Exception):        mmcode = 2
-class BadTwComment(Exception):            mmcode = 2
+class BadTwLabel(Exception):              mmcode = 2
 class BaseConversionError(Exception):     mmcode = 2
 class BaseConversionPadError(Exception):  mmcode = 2
 class TransactionChainMismatch(Exception):mmcode = 2
+class ObjectInitError(Exception):         mmcode = 2
 
 # 3: yellow hl, 'MMGen Error' + exception + message
 class RPCFailure(Exception):              mmcode = 3
diff --git a/mmgen/main_split.py b/mmgen/main_split.py
index a60ded14..d38d12c8 100755
--- a/mmgen/main_split.py
+++ b/mmgen/main_split.py
@@ -104,7 +104,7 @@ if len(cmd_args) != 2:
 
 from .obj import MMGenID
 try:
-	mmids = [MMGenID(a,on_fail='die') for a in cmd_args]
+	mmids = [MMGenID(a) for a in cmd_args]
 except:
 	die(1,'Command line arguments must be valid MMGen IDs')
 
diff --git a/mmgen/main_wallet.py b/mmgen/main_wallet.py
index 24665243..d4be11e1 100755
--- a/mmgen/main_wallet.py
+++ b/mmgen/main_wallet.py
@@ -148,10 +148,10 @@ if invoked_as == 'subgen':
 	from .obj import SubSeedIdx
 	ss_idx = SubSeedIdx(cmd_args.pop())
 elif invoked_as == 'seedsplit':
-	from .obj import SeedSplitSpecifier
+	from .obj import get_obj,SeedSplitSpecifier
 	master_share = MasterShareIdx(opt.master_share) if opt.master_share else None
 	if cmd_args:
-		sss = SeedSplitSpecifier(cmd_args.pop(),on_fail='silent')
+		sss = get_obj(SeedSplitSpecifier,s=cmd_args.pop(),silent=True)
 		if master_share:
 			if not sss:
 				sss = SeedSplitSpecifier('1:2')
diff --git a/mmgen/obj.py b/mmgen/obj.py
index fab4c5f1..3430a69a 100755
--- a/mmgen/obj.py
+++ b/mmgen/obj.py
@@ -34,14 +34,42 @@ class aInitMeta(type):
 		await instance.__ainit__(*args,**kwargs)
 		return instance
 
-def is_mmgen_seed_id(s):        return SeedID(sid=s,on_fail='silent')
-def is_mmgen_idx(s):            return AddrIdx(s,on_fail='silent')
-def is_addrlist_id(s):          return AddrListID(s,on_fail='silent')
-def is_seed_split_specifier(s): return SeedSplitSpecifier(s,on_fail='silent')
+def get_obj(objname,*args,**kwargs):
+	"""
+	Wrapper for data objects
+	- If the object throws an exception on instantiation, return False, otherwise return the object.
+	- If silent is True, suppress display of the exception.
+	- If return_bool is True, return True instead of the object.
+	Only keyword args are accepted.
+	"""
+	assert args == (), 'get_obj_chk1'
 
-def is_mmgen_id(proto,s):  return MMGenID(proto,s,on_fail='silent')
-def is_coin_addr(proto,s): return CoinAddr(proto,s,on_fail='silent')
-def is_wif(proto,s):       return WifKey(proto,s,on_fail='silent')
+	silent,return_bool = (False,False)
+	if 'silent' in kwargs:
+		silent = kwargs['silent']
+		del kwargs['silent']
+	if 'return_bool' in kwargs:
+		return_bool = kwargs['return_bool']
+		del kwargs['return_bool']
+
+	try:
+		ret = objname(**kwargs)
+	except Exception as e:
+		if not silent:
+			from .util import msg
+			msg(f'{e!s}')
+		return False
+	else:
+		return True if return_bool else ret
+
+def is_mmgen_seed_id(s):   return get_obj(SeedID,     sid=s, silent=True,return_bool=True)
+def is_mmgen_idx(s):       return get_obj(AddrIdx,    n=s,   silent=True,return_bool=True)
+def is_addrlist_id(s):     return get_obj(AddrListID, sid=s, silent=True,return_bool=True)
+def is_seed_split_specifier(s): return get_obj(SeedSplitSpecifier, s=s, silent=True,return_bool=True)
+
+def is_mmgen_id(proto,s):  return get_obj(MMGenID,  proto=proto, id_str=s, silent=True,return_bool=True)
+def is_coin_addr(proto,s): return get_obj(CoinAddr, proto=proto, addr=s,   silent=True,return_bool=True)
+def is_wif(proto,s):       return get_obj(WifKey,   proto=proto, wif=s,    silent=True,return_bool=True)
 
 def truncate_str(s,width): # width = screen width
 	wide_count = 0
@@ -88,15 +116,7 @@ class MMGenList(list,MMGenObject): pass
 class MMGenDict(dict,MMGenObject): pass
 class AddrListData(list,MMGenObject): pass
 
-class InitErrors(object):
-
-	on_fail='die'
-
-	@classmethod
-	def arg_chk(cls,on_fail):
-		cls.on_fail = on_fail
-		assert on_fail in ('die','return','silent','raise'),(
-			"'{}': invalid value for 'on_fail' in class {}".format(on_fail,cls.__name__) )
+class InitErrors:
 
 	@classmethod
 	def init_fail(cls,e,m,e2=None,m2=None,objname=None,preformat=False):
@@ -104,27 +124,19 @@ class InitErrors(object):
 		if preformat:
 			errmsg = m
 		else:
-			fs = "{!r}: value cannot be converted to {} {}({})"
-			e2_fmt = '({}) '.format(e2.args[0]) if e2 else ''
-			errmsg = fs.format(m,objname or cls.__name__,e2_fmt,e.args[0])
+			errmsg = '{!r}: value cannot be converted to {} {}({!s})'.format(
+				m,
+				(objname or cls.__name__),
+				(f'({e2!s}) ' if e2 else ''),
+				e )
 
 		if m2:
-			errmsg = '{!r}\n{}'.format(m2,errmsg)
+			errmsg = repr(m2) + '\n' + errmsg
 
-		from .util import die,msg
-		if cls.on_fail == 'silent':
-			return None # TODO: return False instead?
-		elif cls.on_fail == 'return':
-			if errmsg:
-				msg(errmsg)
-			return None # TODO: return False instead?
-		elif g.traceback or cls.on_fail == 'raise':
-			if hasattr(cls,'exc'):
-				raise cls.exc(errmsg)
-			else:
-				raise
-		elif cls.on_fail == 'die':
-			die(1,errmsg)
+		if hasattr(cls,'exc'):
+			raise cls.exc(errmsg)
+		else:
+			raise ObjectInitError(errmsg)
 
 	@classmethod
 	def method_not_implemented(cls):
@@ -201,10 +213,9 @@ class Int(int,Hilite,InitErrors):
 	max_digits = None
 	color = 'red'
 
-	def __new__(cls,n,base=10,on_fail='raise'):
+	def __new__(cls,n,base=10):
 		if type(n) == cls:
 			return n
-		cls.arg_chk(on_fail)
 		try:
 			me = int.__new__(cls,str(n),base)
 			if cls.min_val != None:
@@ -246,9 +257,9 @@ class ImmutableAttr: # Descriptor
 			"convert this attribute's type"
 			if type(dtype) == str:
 				if include_proto:
-					self.conv = lambda instance,value: globals()[dtype](instance.proto,value,on_fail='raise')
+					self.conv = lambda instance,value: globals()[dtype](instance.proto,value)
 				else:
-					self.conv = lambda instance,value: globals()[dtype](value,on_fail='raise')
+					self.conv = lambda instance,value: globals()[dtype](value)
 			else:
 				if set_none_ok:
 					self.conv = lambda instance,value: None if value is None else dtype(value)
@@ -359,28 +370,27 @@ class AddrIdx(MMGenIdx): max_digits = 7
 
 class AddrIdxList(list,InitErrors,MMGenObject):
 	max_len = 1000000
-	def __init__(self,fmt_str=None,idx_list=None,on_fail='die',sep=','):
-		type(self).arg_chk(on_fail)
+	def __init__(self,fmt_str=None,idx_list=None,sep=','):
 		try:
 			if idx_list:
-				return list.__init__(self,sorted({AddrIdx(i,on_fail='raise') for i in idx_list}))
+				return list.__init__(self,sorted({AddrIdx(i) for i in idx_list}))
 			elif fmt_str:
 				ret = []
 				for i in (fmt_str.split(sep)):
 					j = i.split('-')
 					if len(j) == 1:
-						idx = AddrIdx(i,on_fail='raise')
+						idx = AddrIdx(i)
 						if not idx:
 							break
 						ret.append(idx)
 					elif len(j) == 2:
-						beg = AddrIdx(j[0],on_fail='raise')
+						beg = AddrIdx(j[0])
 						if not beg:
 							break
-						end = AddrIdx(j[1],on_fail='raise')
+						end = AddrIdx(j[1])
 						if not beg or (end < beg):
 							break
-						ret.extend([AddrIdx(x,on_fail='raise') for x in range(beg,end+1)])
+						ret.extend([AddrIdx(x) for x in range(beg,end+1)])
 					else: break
 				else:
 					return list.__init__(self,sorted(set(ret))) # fell off end of loop - success
@@ -393,8 +403,7 @@ class MMGenRange(tuple,InitErrors,MMGenObject):
 	min_idx = None
 	max_idx = None
 
-	def __new__(cls,*args,on_fail='die'):
-		cls.arg_chk(on_fail)
+	def __new__(cls,*args):
 		try:
 			if len(args) == 1:
 				s = args[0]
@@ -449,10 +458,9 @@ class BTCAmt(Decimal,Hilite,InitErrors):
 	forbidden_types = (float,int)
 
 	# NB: 'from_decimal' rounds down to precision of 'min_coin_unit'
-	def __new__(cls,num,from_unit=None,from_decimal=False,on_fail='die'):
+	def __new__(cls,num,from_unit=None,from_decimal=False):
 		if type(num) == cls:
 			return num
-		cls.arg_chk(on_fail)
 		try:
 			if from_unit:
 				assert from_unit in cls.units,(
@@ -546,10 +554,9 @@ class CoinAddr(str,Hilite,InitErrors,MMGenObject):
 	hex_width = 40
 	width = 1
 	trunc_ok = False
-	def __new__(cls,proto,addr,on_fail='die'):
+	def __new__(cls,proto,addr):
 		if type(addr) == cls:
 			return addr
-		cls.arg_chk(on_fail)
 		try:
 			assert set(addr) <= set(ascii_letters+digits),'contains non-alphanumeric characters'
 			me = str.__new__(cls,addr)
@@ -571,11 +578,11 @@ class TokenAddr(CoinAddr):
 	color = 'blue'
 
 class ViewKey(object):
-	def __new__(cls,proto,viewkey,on_fail='die'):
+	def __new__(cls,proto,viewkey):
 		if proto.name == 'Zcash':
-			return ZcashViewKey.__new__(ZcashViewKey,proto,viewkey,on_fail)
+			return ZcashViewKey.__new__(ZcashViewKey,proto,viewkey)
 		elif proto.name == 'Monero':
-			return MoneroViewKey.__new__(MoneroViewKey,viewkey,on_fail)
+			return MoneroViewKey.__new__(MoneroViewKey,viewkey)
 		else:
 			raise ValueError(f'{proto.name}: protocol does not support view keys')
 
@@ -585,10 +592,9 @@ class SeedID(str,Hilite,InitErrors):
 	color = 'blue'
 	width = 8
 	trunc_ok = False
-	def __new__(cls,seed=None,sid=None,on_fail='die'):
+	def __new__(cls,seed=None,sid=None):
 		if type(sid) == cls:
 			return sid
-		cls.arg_chk(on_fail)
 		try:
 			if seed:
 				from .seed import SeedBase
@@ -606,10 +612,9 @@ class SeedID(str,Hilite,InitErrors):
 class SubSeedIdx(str,Hilite,InitErrors):
 	color = 'red'
 	trunc_ok = False
-	def __new__(cls,s,on_fail='die'):
+	def __new__(cls,s):
 		if type(s) == cls:
 			return s
-		cls.arg_chk(on_fail)
 		try:
 			assert isinstance(s,str),'not a string or string subclass'
 			idx = s[:-1] if s[-1] in 'SsLl' else s
@@ -631,15 +636,14 @@ class MMGenID(str,Hilite,InitErrors,MMGenObject):
 	color = 'orange'
 	width = 0
 	trunc_ok = False
-	def __new__(cls,proto,id_str,on_fail='die'):
-		cls.arg_chk(on_fail)
+	def __new__(cls,proto,id_str):
 		try:
 			ss = str(id_str).split(':')
 			assert len(ss) in (2,3),'not 2 or 3 colon-separated items'
-			t = proto.addr_type((ss[1],proto.dfl_mmtype)[len(ss)==2],on_fail='raise')
+			t = proto.addr_type((ss[1],proto.dfl_mmtype)[len(ss)==2])
 			me = str.__new__(cls,'{}:{}:{}'.format(ss[0],t,ss[-1]))
-			me.sid = SeedID(sid=ss[0],on_fail='raise')
-			me.idx = AddrIdx(ss[-1],on_fail='raise')
+			me.sid = SeedID(sid=ss[0])
+			me.idx = AddrIdx(ss[-1])
 			me.mmtype = t
 			assert t in proto.mmtypes, f'{t}: invalid address type for {proto.cls_name}'
 			me.al_id = str.__new__(AddrListID,me.sid+':'+me.mmtype) # checks already done
@@ -653,13 +657,12 @@ class TwMMGenID(str,Hilite,InitErrors,MMGenObject):
 	color = 'orange'
 	width = 0
 	trunc_ok = False
-	def __new__(cls,proto,id_str,on_fail='die'):
+	def __new__(cls,proto,id_str):
 		if type(id_str) == cls:
 			return id_str
-		cls.arg_chk(on_fail)
 		ret = None
 		try:
-			ret = MMGenID(proto,id_str,on_fail='raise')
+			ret = MMGenID(proto,id_str)
 			sort_key,idtype = ret.sort_key,'mmgen'
 		except Exception as e:
 			try:
@@ -680,14 +683,14 @@ class TwMMGenID(str,Hilite,InitErrors,MMGenObject):
 
 # non-displaying container for TwMMGenID,TwComment
 class TwLabel(str,InitErrors,MMGenObject):
-	def __new__(cls,proto,text,on_fail='die'):
+	exc = BadTwLabel
+	def __new__(cls,proto,text):
 		if type(text) == cls:
 			return text
-		cls.arg_chk(on_fail)
 		try:
 			ts = text.split(None,1)
-			mmid = TwMMGenID(proto,ts[0],on_fail='raise')
-			comment = TwComment(ts[1] if len(ts) == 2 else '',on_fail='raise')
+			mmid = TwMMGenID(proto,ts[0])
+			comment = TwComment(ts[1] if len(ts) == 2 else '')
 			me = str.__new__( cls, mmid + (' ' + comment if comment else '') )
 			me.mmid = mmid
 			me.comment = comment
@@ -701,10 +704,9 @@ class HexStr(str,Hilite,InitErrors):
 	width = None
 	hexcase = 'lower'
 	trunc_ok = False
-	def __new__(cls,s,on_fail='die',case=None):
+	def __new__(cls,s,case=None):
 		if type(s) == cls:
 			return s
-		cls.arg_chk(on_fail)
 		if case == None:
 			case = cls.hexcase
 		try:
@@ -730,10 +732,9 @@ class WifKey(str,Hilite,InitErrors):
 	"""
 	width = 53
 	color = 'blue'
-	def __new__(cls,proto,wif,on_fail='die'):
+	def __new__(cls,proto,wif):
 		if type(wif) == cls:
 			return wif
-		cls.arg_chk(on_fail)
 		try:
 			assert set(wif) <= set(ascii_letters+digits),'not an ascii alphanumeric string'
 			proto.parse_wif(wif) # raises exception on error
@@ -742,12 +743,12 @@ class WifKey(str,Hilite,InitErrors):
 			return cls.init_fail(e,wif)
 
 class PubKey(HexStr,MMGenObject): # TODO: add some real checks
-	def __new__(cls,s,compressed,on_fail='die'):
+	def __new__(cls,s,compressed):
 		try:
 			assert type(compressed) == bool,"'compressed' must be of type bool"
 		except Exception as e:
 			return cls.init_fail(e,s)
-		me = HexStr.__new__(cls,s,case='lower',on_fail=on_fail)
+		me = HexStr.__new__(cls,s,case='lower')
 		if me:
 			me.compressed = compressed
 			return me
@@ -767,12 +768,9 @@ class PrivKey(str,Hilite,InitErrors,MMGenObject):
 	wif        = ImmutableAttr(WifKey,typeconv=False)
 
 	# initialize with (priv_bin,compressed), WIF or self
-	def __new__(cls,proto,s=None,compressed=None,wif=None,pubkey_type=None,on_fail='die'):
-
+	def __new__(cls,proto,s=None,compressed=None,wif=None,pubkey_type=None):
 		if type(s) == cls:
 			return s
-		cls.arg_chk(on_fail)
-
 		if wif:
 			try:
 				assert s == None,"'wif' and key hex args are mutually exclusive"
@@ -801,7 +799,7 @@ class PrivKey(str,Hilite,InitErrors,MMGenObject):
 					assert compressed is not None, "'compressed' arg missing"
 					assert type(compressed) == bool,"{!r}: 'compressed' not of type 'bool'".format(compressed)
 					me = str.__new__(cls,proto.preprocess_key(s,pubkey_type).hex())
-					me.wif = WifKey(proto,proto.hex2wif(me,pubkey_type,compressed),on_fail='raise')
+					me.wif = WifKey(proto,proto.hex2wif(me,pubkey_type,compressed))
 					me.compressed = compressed
 				me.pubkey_type = pubkey_type
 				me.orig_hex = s.hex() # save the non-preprocessed key
@@ -814,8 +812,7 @@ class AddrListID(str,Hilite,InitErrors,MMGenObject):
 	width = 10
 	trunc_ok = False
 	color = 'yellow'
-	def __new__(cls,sid,mmtype,on_fail='die'):
-		cls.arg_chk(on_fail)
+	def __new__(cls,sid,mmtype):
 		try:
 			assert type(sid) == SeedID,"{!r} not a SeedID instance".format(sid)
 			if not isinstance(mmtype,(MMGenAddrType,MMGenPasswordType)):
@@ -835,10 +832,9 @@ class MMGenLabel(str,Hilite,InitErrors):
 	min_len = 0
 	max_screen_width = 0 # if != 0, overrides max_len
 	desc = 'label'
-	def __new__(cls,s,on_fail='die',msg=None):
+	def __new__(cls,s,msg=None):
 		if type(s) == cls:
 			return s
-		cls.arg_chk(on_fail)
 		for k in cls.forbidden,cls.allowed:
 			assert type(k) == list
 			for ch in k: assert type(ch) == str and len(ch) == 1
@@ -874,7 +870,6 @@ class MMGenWalletLabel(MMGenLabel):
 class TwComment(MMGenLabel):
 	max_screen_width = 80
 	desc = 'tracking wallet comment'
-	exc = BadTwComment
 
 class MMGenTxLabel(MMGenLabel):
 	max_len = 72
@@ -889,18 +884,17 @@ class MMGenPWIDString(MMGenLabel):
 
 class SeedSplitSpecifier(str,Hilite,InitErrors,MMGenObject):
 	color = 'red'
-	def __new__(cls,s,on_fail='raise'):
+	def __new__(cls,s):
 		if type(s) == cls:
 			return s
-		cls.arg_chk(on_fail)
 		try:
 			arr = s.split(':')
 			assert len(arr) in (2,3), 'cannot be parsed'
 			a,b,c = arr if len(arr) == 3 else ['default'] + arr
 			me = str.__new__(cls,s)
-			me.id = SeedSplitIDString(a,on_fail=on_fail)
-			me.idx = SeedShareIdx(b,on_fail=on_fail)
-			me.count = SeedShareCount(c,on_fail=on_fail)
+			me.id = SeedSplitIDString(a)
+			me.idx = SeedShareIdx(b)
+			me.count = SeedShareCount(c)
 			assert me.idx <= me.count, 'share index greater than share count'
 			return me
 		except Exception as e:
@@ -936,10 +930,9 @@ class MMGenAddrType(str,Hilite,InitErrors,MMGenObject):
 		'Z': ati('zcash_z','zcash_z',False,'zcash_z', 'zcash_z', 'wif',     ('viewkey',),      'Zcash z-address'),
 		'M': ati('monero', 'monero', False,'monero',  'monero',  'spendkey',('viewkey','wallet_passwd'),'Monero address'),
 	}
-	def __new__(cls,proto,id_str,on_fail='die',errmsg=None):
+	def __new__(cls,proto,id_str,errmsg=None):
 		if type(id_str) == cls:
 			return id_str
-		cls.arg_chk(on_fail)
 		try:
 			for k,v in cls.mmtypes.items():
 				if id_str in (k,v.name):
diff --git a/mmgen/protocol.py b/mmgen/protocol.py
index e361de9d..3083b2a1 100755
--- a/mmgen/protocol.py
+++ b/mmgen/protocol.py
@@ -168,11 +168,11 @@ class CoinProtocol(MMGenObject):
 		def coin_addr(self,addr):
 			return CoinAddr( proto=self, addr=addr )
 
-		def addr_type(self,id_str,on_fail='die'):
-			return MMGenAddrType(proto=self,id_str=id_str,on_fail=on_fail)
+		def addr_type(self,id_str):
+			return MMGenAddrType( proto=self, id_str=id_str )
 
-		def priv_key(self,s,on_fail='die'):
-			return PrivKey(proto=self,s=s,on_fail=on_fail)
+		def priv_key(self,s):
+			return PrivKey( proto=self, s=s )
 
 	class Secp256k1(Base):
 		"""
diff --git a/mmgen/tw.py b/mmgen/tw.py
index c06a84b5..e839da6c 100755
--- a/mmgen/tw.py
+++ b/mmgen/tw.py
@@ -33,8 +33,8 @@ def CUR_RIGHT(n): return '\033[{}C'.format(n)
 
 def get_tw_label(proto,s):
 	try:
-		return TwLabel(proto,s,on_fail='raise')
-	except BadTwComment:
+		return TwLabel(proto,s)
+	except BadTwLabel:
 		raise
 	except:
 		return None
@@ -410,7 +410,7 @@ Actions: [q]uit view, [p]rint to file, pager [v]iew, [w]ide view, add [l]abel:
 		while True:
 			ret = my_raw_input(f'Enter {self.item_desc} number (or RETURN to return to main menu): ')
 			if ret == '': return (None,None) if action == 'a_lbl_add' else None
-			n = AddrIdx(ret,on_fail='silent')
+			n = get_obj(AddrIdx,n=ret,silent=True)
 			if not n or n < 1 or n > len(self.unspent):
 				msg(f'Choice must be a single number between 1 and {len(self.unspent)}')
 			else:
@@ -424,7 +424,7 @@ Actions: [q]uit view, [p]rint to file, pager [v]iew, [w]ide view, add [l]abel:
 									f'Removing label for {self.item_desc} #{n}.  Is this what you want?'):
 								return n,s
 						elif s:
-							if TwComment(s,on_fail='return'):
+							if get_obj(TwComment,s=s):
 								return n,s
 				else:
 					if action == 'a_addr_delete':
@@ -801,8 +801,8 @@ class TrackingWallet(MMGenObject,metaclass=aInitMeta):
 	def conv_types(self,ad):
 		for k,v in ad.items():
 			if k not in ('params','coin'):
-				v['mmid'] = TwMMGenID(self.proto,v['mmid'],on_fail='raise')
-				v['comment'] = TwComment(v['comment'],on_fail='raise')
+				v['mmid'] = TwMMGenID(self.proto,v['mmid'])
+				v['comment'] = TwComment(v['comment'])
 
 	@property
 	def data_root(self):
@@ -918,9 +918,10 @@ class TrackingWallet(MMGenObject,metaclass=aInitMeta):
 	# returns on failure
 	@write_mode
 	async def add_label(self,arg1,label='',addr=None,silent=False,on_fail='return'):
+		assert on_fail in ('return','raise'), 'add_label_chk1'
 		mmaddr,coinaddr = None,None
 		if is_coin_addr(self.proto,addr or arg1):
-			coinaddr = CoinAddr(self.proto,addr or arg1,on_fail='return')
+			coinaddr = get_obj(CoinAddr,proto=self.proto,addr=addr or arg1)
 		if is_mmgen_id(self.proto,arg1):
 			mmaddr = TwMMGenID(self.proto,arg1)
 
@@ -948,11 +949,14 @@ class TrackingWallet(MMGenObject,metaclass=aInitMeta):
 
 		mmaddr = TwMMGenID(self.proto,mmaddr)
 
-		cmt = TwComment(label,on_fail=on_fail)
+		cmt = TwComment(label) if on_fail=='raise' else get_obj(TwComment,s=label)
 		if cmt in (False,None):
 			return False
 
-		lbl = TwLabel(self.proto,mmaddr + ('',' '+cmt)[bool(cmt)],on_fail=on_fail)
+		lbl_txt = mmaddr + (' ' + cmt if cmt else '')
+		lbl = (
+			TwLabel(self.proto,lbl_txt) if on_fail == 'raise' else
+			get_obj(TwLabel,proto=self.proto,text=lbl_txt) )
 
 		if await self.set_label(coinaddr,lbl) == False:
 			if not silent:
diff --git a/mmgen/tx.py b/mmgen/tx.py
index 8dce9a57..ebc06644 100755
--- a/mmgen/tx.py
+++ b/mmgen/tx.py
@@ -616,8 +616,9 @@ class MMGenTX:
 		# given tx size and absolute fee or fee spec, return absolute fee
 		# relative fee is N+<first letter of unit name>
 		def process_fee_spec(self,tx_fee,tx_size):
-			if self.proto.coin_amt(tx_fee,on_fail='silent'):
-				return self.proto.coin_amt(tx_fee)
+			fee = get_obj(self.proto.coin_amt,num=tx_fee,silent=True)
+			if fee:
+				return fee
 			else:
 				import re
 				units = {u[0]:u for u in self.proto.coin_amt.units}
@@ -733,7 +734,7 @@ class MMGenTX:
 			while True:
 				reply = my_raw_input(prompt).strip()
 				if reply:
-					selected = AddrIdxList(fmt_str=','.join(reply.split()),on_fail='return')
+					selected = get_obj(AddrIdxList, fmt_str=','.join(reply.split()) )
 					if selected:
 						if selected[-1] <= len(unspent):
 							return selected
@@ -1004,7 +1005,7 @@ class MMGenTX:
 			return self.inputs[0].sequence == g.max_int - 2
 
 		def check_txfile_hex_data(self):
-			self.hex = HexStr(self.hex,on_fail='raise')
+			self.hex = HexStr(self.hex)
 
 		def parse_txfile_hex_data(self):
 			pass
@@ -1242,7 +1243,7 @@ class MMGenTX:
 				tx_decoded = await self.rpc.call('decoderawtransaction',ret['hex'])
 				new.compare_size_and_estimated_size(tx_decoded)
 				new.check_hex_tx_matches_mmgen_tx(dtx)
-				new.coin_txid = CoinTxID(dtx['txid'],on_fail='raise')
+				new.coin_txid = CoinTxID(dtx['txid'])
 				if not new.coin_txid == tx_decoded['txid']:
 					raise BadMMGenTxID('txid mismatch (after signing)')
 				msg('OK')
diff --git a/mmgen/txfile.py b/mmgen/txfile.py
index 7cfb61fb..c14882b7 100755
--- a/mmgen/txfile.py
+++ b/mmgen/txfile.py
@@ -65,13 +65,13 @@ class MMGenTxFile:
 			tx_data = tx_data.splitlines()
 			assert len(tx_data) >= 5,'number of lines less than 5'
 			assert len(tx_data[0]) == 6,'invalid length of first line'
-			self.chksum = HexStr(tx_data.pop(0),on_fail='raise')
+			self.chksum = HexStr(tx_data.pop(0))
 			assert self.chksum == make_chksum_6(' '.join(tx_data)),'file data does not match checksum'
 
 			if len(tx_data) == 6:
 				assert len(tx_data[-1]) == 64,'invalid coin TxID length'
 				desc = f'coin TxID'
-				tx.coin_txid = CoinTxID(tx_data.pop(-1),on_fail='raise')
+				tx.coin_txid = CoinTxID(tx_data.pop(-1))
 
 			if len(tx_data) == 5:
 				# rough check: allow for 4-byte utf8 characters + base58 (4 * 11 / 8 = 6 (rounded up))
@@ -83,7 +83,7 @@ class MMGenTxFile:
 					comment = baseconv.tobytes(c,'b58').decode()
 					assert comment != False,'invalid comment'
 					desc = 'comment'
-					tx.label = MMGenTxLabel(comment,on_fail='raise')
+					tx.label = MMGenTxLabel(comment)
 
 			desc = 'number of lines' # four required lines
 			metadata,tx.hex,inputs_data,outputs_data = tx_data
@@ -113,7 +113,7 @@ class MMGenTxFile:
 			txid,send_amt,tx.timestamp,blockcount = metadata
 
 			desc = 'TxID in metadata'
-			tx.txid = MMGenTxID(txid,on_fail='raise')
+			tx.txid = MMGenTxID(txid)
 			desc = 'send amount in metadata'
 			tx.send_amt = tx.proto.coin_amt(send_amt)
 			desc = 'block count in metadata'
diff --git a/mmgen/wallet.py b/mmgen/wallet.py
index 4e6a2a36..f37a664a 100755
--- a/mmgen/wallet.py
+++ b/mmgen/wallet.py
@@ -724,7 +724,7 @@ class MMGenWallet(WalletEnc):
 			msg_r(prompt)
 			ret = my_raw_input('')
 			if ret:
-				lbl = MMGenWalletLabel(ret,on_fail='return')
+				lbl = get_obj(MMGenWalletLabel,s=ret)
 				if lbl:
 					return lbl
 				else:
diff --git a/test/objtest.py b/test/objtest.py
index 129da1c9..2e8e2887 100755
--- a/test/objtest.py
+++ b/test/objtest.py
@@ -41,6 +41,7 @@ opts_data = {
 		'options': """
 -h, --help         Print this help message
 --, --longhelp     Print help message for long options (common options)
+-g, --getobj       Instantiate objects with get_obj() wrapper
 -q, --quiet        Produce quieter output
 -s, --silent       Silence output of tested objects
 -S, --super-silent Silence all output except for errors
@@ -51,12 +52,11 @@ opts_data = {
 
 cmd_args = opts.init(opts_data)
 
-def run_test(test,arg,input_data):
+def run_test(test,arg,input_data,arg1,exc_name):
 	arg_copy = arg
-	kwargs = {'on_fail':'silent'} if opt.silent else {'on_fail':'die'}
+	kwargs = {}
 	ret_chk = arg
 	ret_idx = None
-	exc_type = None
 	if input_data == 'good' and type(arg) == tuple:
 		arg,ret_chk = arg
 	if type(arg) == dict: # pass one arg + kwargs to constructor
@@ -76,28 +76,42 @@ def run_test(test,arg,input_data):
 			ret_idx = arg['ret_idx']
 			del arg['ret_idx']
 			del arg_copy['ret_idx']
-		if 'ExcType' in arg:
-			exc_type = arg['ExcType']
-			del arg['ExcType']
-			del arg_copy['ExcType']
 		kwargs.update(arg)
 	elif type(arg) == tuple:
 		args = arg
 	else:
 		args = [arg]
+
+	if opt.getobj:
+		if args:
+			assert len(args) == 1, 'objtest_chk1: only one positional arg is allowed'
+			kwargs.update( { arg1: args[0] } )
+		if opt.silent:
+			kwargs.update( { 'silent': True } )
+
 	try:
 		if not opt.super_silent:
 			arg_disp = repr(arg_copy[0] if type(arg_copy) == tuple else arg_copy)
 			msg_r((orange,green)[input_data=='good']('{:<22}'.format(arg_disp+':')))
 		cls = globals()[test]
-		ret = cls(*args,**kwargs)
+
+		if opt.getobj:
+			ret = get_obj(globals()[test],**kwargs)
+		else:
+			ret = cls(*args,**kwargs)
+
 		bad_ret = list() if issubclass(cls,list) else None
 
 		if isinstance(ret_chk,str): ret_chk = ret_chk.encode()
 		if isinstance(ret,str): ret = ret.encode()
 
-		if (opt.silent and input_data=='bad' and ret!=bad_ret) or (not opt.silent and input_data=='bad'):
-			raise UserWarning("Non-'None' return value {} with bad input data".format(repr(ret)))
+		if opt.getobj:
+			if input_data == 'bad':
+				assert ret == False, 'non-False return on bad input data'
+		else:
+			if (opt.silent and input_data=='bad' and ret!=bad_ret) or (not opt.silent and input_data=='bad'):
+				raise UserWarning(f"Non-'None' return value {ret!r} with bad input data")
+
 		if opt.silent and input_data=='good' and ret==bad_ret:
 			raise UserWarning("'None' returned with good input data")
 
@@ -105,20 +119,31 @@ def run_test(test,arg,input_data):
 			if ret_idx:
 				ret_chk = arg[list(arg.keys())[ret_idx]].encode()
 			if ret != ret_chk and repr(ret) != repr(ret_chk):
-				raise UserWarning("Return value ({!r}) doesn't match expected value ({!r})".format(ret,ret_chk))
-		if not opt.super_silent:
+				raise UserWarning(f"Return value ({ret!r}) doesn't match expected value ({ret_chk!r})")
+
+		if opt.super_silent:
+			return
+
+		if opt.getobj and (not opt.silent and input_data == 'bad'):
+			pass
+		else:
 			try: ret_disp = ret.decode()
 			except: ret_disp = ret
 			msg(f'==> {ret_disp!r}')
 
 		if opt.verbose and issubclass(cls,MMGenObject):
 			ret.pmsg() if hasattr(ret,'pmsg') else pmsg(ret)
+
 	except Exception as e:
-		if not type(e).__name__ == exc_type:
+		if not type(e).__name__ == exc_name:
+			msg(f'Incorrect exception: expected {exc_name} but got {type(e).__name__}')
 			raise
-		if not opt.super_silent:
-			msg_r(' {}'.format(yellow(exc_type+':')))
-			msg(e.args[0])
+		if opt.super_silent:
+			pass
+		elif opt.silent:
+			msg(f'==> {exc_name}')
+		else:
+			msg( yellow(f' {exc_name}:') + str(e) )
 	except SystemExit as e:
 		if input_data == 'good':
 			raise ValueError('Error on good input data')
@@ -137,10 +162,17 @@ def do_loop():
 	clr = None
 	utests = cmd_args
 	for test in test_data:
+		arg1 = test_data[test].get('arg1')
 		if utests and test not in utests: continue
 		nl = ('\n','')[bool(opt.super_silent) or clr == None]
 		clr = (blue,nocolor)[bool(opt.super_silent)]
-		msg(clr('{}Testing {}'.format(nl,test)))
+
+		if opt.getobj and arg1 is None:
+			msg(gray(f'{nl}Skipping {test}'))
+			continue
+		else:
+			msg(clr(f'{nl}Testing {test}'))
+
 		for k in ('bad','good'):
 			if not opt.silent:
 				msg(purple(capfirst(k)+' input:'))
@@ -149,6 +181,8 @@ def do_loop():
 					test,
 					arg,
 					input_data = k,
+					arg1       = arg1,
+					exc_name   = test_data[test].get('exc_name') or 'ObjectInitError',
 				)
 
 from mmgen.protocol import init_proto_from_opts
diff --git a/test/objtest_py_d/ot_btc_mainnet.py b/test/objtest_py_d/ot_btc_mainnet.py
index 0407781e..ee2a15a4 100755
--- a/test/objtest_py_d/ot_btc_mainnet.py
+++ b/test/objtest_py_d/ot_btc_mainnet.py
@@ -19,6 +19,7 @@ ssm = str(SeedShareCount.max_val)
 
 tests = {
 	'Int': {
+		'arg1': 'n',
 		'bad':  ('1L',0.0,'0.0','1.0',1.0,'s',1.1,'1.1'),
 		'good': (
 			('0',0),('-1',-1),('7',7),-1,0,1,9999999,
@@ -29,22 +30,27 @@ tests = {
 		)
 	},
 	'AddrIdx': {
+		'arg1': 'n',
 		'bad':  ('s',1.1,10000000,-1,0),
 		'good': (('7',7),(1,1),(9999999,9999999))
 	},
 	'SeedShareIdx': {
+		'arg1': 'n',
 		'bad':  ('s',1.1,1025,-1,0),
 		'good': (('7',7),(1,1),(1024,1024))
 	},
 	'SeedShareCount': {
+		'arg1': 'n',
 		'bad':  ('s',2.1,1025,-1,0,1),
 		'good': (('7',7),(2,2),(1024,1024))
 	},
 	'MasterShareIdx': {
+		'arg1': 'n',
 		'bad':  ('s',1.1,1025,-1,0),
 		'good': (('7',7),(1,1),(1024,1024))
 	},
 	'AddrIdxList': {
+		'arg1': 'fmt_str',
 		'bad':  ('x','5,9,1-2-3','8,-11','66,3-2'),
 		'good': (
 			('3,2,2',[2,3]),
@@ -63,6 +69,7 @@ tests = {
 		)
 	},
 	'BTCAmt': {
+		'arg1': 'num',
 		'bad':  ('-3.2','0.123456789',123,'123L','22000000',20999999.12345678,
 					{'num':'1','from_decimal':True},
 					{'num':1,'from_decimal':True},
@@ -86,6 +93,7 @@ tests = {
 		)
 	},
 	'CoinAddr': {
+		'arg1': 'addr',
 		'good':  (
 			{'addr':'1MjjELEy6EJwk8fSNfpS8b5teFRo4X5fZr', 'proto':proto},
 			{'addr':'32GiSWo9zJQgkCmjAaLRrbPwXhKry2jHhj', 'proto':proto},
@@ -97,6 +105,7 @@ tests = {
 		),
 	},
 	'SeedID': {
+		'arg1': 'sid',
 		'bad':  (
 			{'sid':'я'},
 			{'sid':'F00F00'},
@@ -106,13 +115,19 @@ tests = {
 			{'sid':'f00baa12'},
 			'я',r32,'abc'
 			),
-		'good': (({'sid':'F00BAA12'},'F00BAA12'),(Seed(r16),Seed(r16).sid))
+		'good': (
+			{'sid':'F00BAA12'},
+			{'seed': Seed(r16),    'ret': SeedID(seed=Seed(r16))},
+			{'sid': Seed(r16).sid, 'ret': SeedID(seed=Seed(r16))}
+			)
 	},
 	'SubSeedIdx': {
+		'arg1': 's',
 		'bad':  (33,'x','я','1x',200,'1ss','L','s','200LS','30ll','s100',str(SubSeedIdxRange.max_idx+1),'0'),
 		'good': (('1','1L'),('1s','1S'),'20S','30L',('300l','300L'),('200','200L'),str(SubSeedIdxRange.max_idx)+'S')
 	},
 	'MMGenID': {
+		'arg1': 'id_str',
 		'bad':  (
 			{'id_str':'x',             'proto':proto},
 			{'id_str':1,               'proto':proto},
@@ -129,6 +144,7 @@ tests = {
 		),
 	},
 	'TwMMGenID': {
+		'arg1': 'id_str',
 		'bad':  (
 			{'id_str':'x',             'proto':proto},
 			{'id_str':'я',             'proto':proto},
@@ -150,6 +166,8 @@ tests = {
 		),
 	},
 	'TwLabel': {
+		'arg1': 'proto',
+		'exc_name': 'BadTwLabel',
 		'bad':  (
 			{'text':'x x',           'proto':proto},
 			{'text':'x я',           'proto':proto},
@@ -163,7 +181,7 @@ tests = {
 			{'text':tw_pfx+' x',     'proto':proto},
 			{'text':tw_pfx+'я x',    'proto':proto},
 			{'text':utf8_ctrl[:40],  'proto':proto},
-			{'text':'F00BAA12:S:1 '+ utf8_ctrl[:40], 'proto':proto, 'on_fail':'raise','ExcType':'BadTwComment'},
+			{'text':'F00BAA12:S:1 '+ utf8_ctrl[:40], 'proto':proto, },
 		),
 		'good':  (
 			{'text':'F00BAA12:99 a comment',            'proto':proto, 'ret':'F00BAA12:L:99 a comment'},
@@ -174,14 +192,17 @@ tests = {
 		),
 	},
 	'MMGenTxID': {
+		'arg1': 's',
 		'bad':  (1,[],'\0','\1','я','g','gg','FF','f00','F00F0012'),
 		'good': ('DEADBE','F00BAA')
 	},
 	'CoinTxID':{
+		'arg1': 's',
 		'bad':  (1,[],'\0','\1','я','g','gg','FF','f00','F00F0012',r16.hex(),r32.hex()+'ee'),
 		'good': (r32.hex(),)
 	},
 	'WifKey': {
+		'arg1': 'proto',
 		'bad': (
 			{'proto':proto, 'wif':1},
 			{'proto':proto, 'wif':[]},
@@ -201,10 +222,12 @@ tests = {
 		)
 	},
 	'PubKey': {
+		'arg1': 's',
 		'bad':  ({'arg':1,'compressed':False},{'arg':'F00BAA12','compressed':False},),
 		'good': ({'arg':'deadbeef','compressed':True},) # TODO: add real pubkeys
 	},
 	'PrivKey': {
+		'arg1': 'proto',
 		'bad': (
 			{'proto':proto, 'wif':1},
 			{'proto':proto, 'wif':'1'},
@@ -227,6 +250,7 @@ tests = {
 		)
 	},
 	'AddrListID': { # a rather pointless test, but do it anyway
+		'arg1': 'sid',
 		'bad':  (
 			{'sid':SeedID(sid='F00BAA12'),'mmtype':'Z','ret':'F00BAA12:Z'},
 		),
@@ -236,10 +260,12 @@ tests = {
 		)
 	},
 	'MMGenWalletLabel': {
+		'arg1': 's',
 		'bad': (utf8_text[:49],utf8_combining[:48],utf8_ctrl[:48],gr_uc_w_ctrl),
 		'good':  (utf8_text[:48],)
 	},
 	'TwComment': {
+		'arg1': 's',
 		'bad': (    utf8_combining[:40],
 					utf8_ctrl[:40],
 					text_jp[:41],
@@ -252,14 +278,17 @@ tests = {
 					text_zh[:40] )
 	},
 	'MMGenTxLabel':{
+		'arg1': 's',
 		'bad': (utf8_text[:73],utf8_combining[:72],utf8_ctrl[:72],gr_uc_w_ctrl),
 		'good':  (utf8_text[:72],)
 	},
 	'MMGenPWIDString': { # forbidden = list(u' :/\\')
+		'arg1': 's',
 		'bad': ('foo/','foo:','foo:\\'),
 		'good': ('qwerty@яяя',)
 	},
 	'MMGenAddrType': {
+		'arg1': 'proto',
 		'bad':  (
 			{'proto':proto, 'id_str':'U',        'ret':'L'},
 			{'proto':proto, 'id_str':'z',        'ret':'L'},
@@ -278,6 +307,7 @@ tests = {
 		)
 	},
 	'MMGenPasswordType': {
+		'arg1': 'proto',
 		'bad':  (
 			{'proto':proto, 'id_str':'U',        'ret':'L'},
 			{'proto':proto, 'id_str':'z',        'ret':'L'},
@@ -291,6 +321,7 @@ tests = {
 		)
 	},
 	'SeedSplitSpecifier': {
+		'arg1': 's',
 		'bad': ('M','αβ:2',1,'0:1','1:1','2:1','3:2','1:2000','abc:0:2'),
 		'good': (
 			('1:2','2:2','alice:2:2','αβ:2:2','1:'+ssm,ssm+':'+ssm)
diff --git a/test/test-release.sh b/test/test-release.sh
index bce62318..9387ef20 100755
--- a/test/test-release.sh
+++ b/test/test-release.sh
@@ -248,6 +248,7 @@ i_obj='Data object'
 s_obj='Testing data objects'
 t_obj="
 	$objtest_py --coin=btc
+	$objtest_py --getobj --coin=btc
 	$objtest_py --coin=btc --testnet=1
 	$objtest_py --coin=ltc
 	$objtest_py --coin=ltc --testnet=1