From 6243a24a0952dfea5373bce5d5dc9f9df1c1822c Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Tue, 23 Mar 2021 18:13:07 -0700
Subject: [PATCH] [otBase] Delete .Format if was introduced by .preWrite()

https://github.com/fonttools/fonttools/pull/2238#issuecomment-805192631
---
 Lib/fontTools/ttLib/tables/otBase.py | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Lib/fontTools/ttLib/tables/otBase.py b/Lib/fontTools/ttLib/tables/otBase.py
index 5ce32c17b..c47e940f0 100644
--- a/Lib/fontTools/ttLib/tables/otBase.py
+++ b/Lib/fontTools/ttLib/tables/otBase.py
@@ -654,9 +654,15 @@ class BaseTable(object):
 
 	def compile(self, writer, font):
 		self.ensureDecompiled()
+		# TODO Following hack to be removed by rewriting how FormatSwitching tables
+		# are handled.
+		# https://github.com/fonttools/fonttools/pull/2238#issuecomment-805192631
 		if hasattr(self, 'preWrite'):
+			deleteFormat = not hasattr(self, 'Format')
 			table = self.preWrite(font)
+			deleteFormat = deleteFormat and hasattr(self, 'Format')
 		else:
+			deleteFormat = False
 			table = self.__dict__.copy()
 
 		# some count references may have been initialized in a custom preWrite; we set
@@ -740,6 +746,9 @@ class BaseTable(object):
 				if conv.isPropagated:
 					writer[conv.name] = value
 
+		if deleteFormat:
+			del self.Format
+
 	def readFormat(self, reader):
 		pass