Document why Book is defined static

This was not clear to someone on talkchess and actually
is not trivial to understand.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

diff --git a/src/search.cpp b/src/search.cpp
index ed18936f760eb71cb7450daa8c12279f7d3f1ef0..1f848183481a573cf59710f2993a1c4fb890a1f2 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -363,7 +363,7 @@ int64_t perft(Position& pos, Depth depth) {
 
 bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) {
 
-  static Book book;
+  static Book book; // Define static to initialize the PRNG only once
 
   // Initialize global search-related variables
   StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = false;