From bf2cd0f5e43c7e3aef37bbc34c3101ea800de17c Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomas@tbabej.com>
Date: Tue, 1 Jan 2019 21:54:38 -0500
Subject: [PATCH] TW-1511: Interpret string subtraction as concanetation with a
 dash

Fixes #1537 (previously known as TW-1511).
---
 src/Variant.cpp | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/Variant.cpp b/src/Variant.cpp
index 630264f7a..842794809 100644
--- a/src/Variant.cpp
+++ b/src/Variant.cpp
@@ -1278,7 +1278,18 @@ Variant& Variant::operator-= (const Variant& other)
     break;
 
   case type_string:
-    throw std::string (STRING_VARIANT_SUB_STRING);
+    switch (right._type)
+    {
+    case type_string:
+      cast (type_string);   _string   += '-' + right._string;   break;
+    case type_boolean:
+    case type_integer:
+    case type_real:
+    case type_date:
+    case type_duration:
+      throw std::string (STRING_VARIANT_SUB_STRING);
+      break;
+    }
     break;
 
   case type_date: