From d7a2ab760e06f87fd0158602e34ce3c2236ed82c Mon Sep 17 00:00:00 2001
From: Marcel Keller <mks.keller@gmail.com>
Date: Tue, 20 Oct 2020 15:30:47 +1100
Subject: [PATCH] Fix multithreaded output.

---
 Tools/SwitchableOutput.h | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/Tools/SwitchableOutput.h b/Tools/SwitchableOutput.h
index 90278d1b..51f6ad04 100644
--- a/Tools/SwitchableOutput.h
+++ b/Tools/SwitchableOutput.h
@@ -12,7 +12,7 @@ using namespace std;
 
 class SwitchableOutput
 {
-    bool on;
+    ostream* out;
 
 public:
     SwitchableOutput(bool on = true)
@@ -22,21 +22,22 @@ public:
 
     void activate(bool on)
     {
-        this->on = on;
+        if (on)
+            out = &cout;
+        else
+            out = 0;
     }
 
     void redirect_to_file(ofstream& out_file)
     {
-        if (!on)
-            this->on = true;
-        cout.rdbuf(out_file.rdbuf());
+        out = &out_file;
     }
 
     template<class T>
     SwitchableOutput& operator<<(const T& value)
     {
-        if (on)
-            cout << value;
+        if (out)
+            *out << value;
         return *this;
 
         cout << flush;
@@ -44,8 +45,8 @@ public:
 
     SwitchableOutput& operator<<(ostream& (*__pf)(ostream&))
     {
-        if (on)
-            cout << __pf;
+        if (out)
+            *out << __pf;
         return *this;
     }
 };