[gnome-chess] Fix Stockfish engine integration

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 592754bed0bc180b194332f2c6347a540bfbd290
Author: Michael Catanzaro <mike catanzaro gmail com>
Date:   Sat May 11 22:24:08 2013 -0500

    Fix Stockfish engine integration
    
    Stockfish seems to go a bit nuts if passed an empty string for
    command-line arguments.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=696474

 src/ai-profile.vala        |    4 +++-
 src/chess-engine-cecp.vala |    2 +-
 src/chess-engine-uci.vala  |    2 +-
 src/chess-engine.vala      |    2 +-
 4 files changed, 6 insertions(+), 4 deletions(-)
---
diff --git a/src/ai-profile.vala b/src/ai-profile.vala
index 07cb636..a06b419 100644
--- a/src/ai-profile.vala
+++ b/src/ai-profile.vala
@@ -4,7 +4,7 @@ public class AIProfile
     public string protocol;
     public string binary;
     public string path;
-    public string args = "";
+    public string args;
     public string[] easy_options;
     public string[] normal_options;
     public string[] hard_options;
@@ -41,6 +41,8 @@ public List<AIProfile> load_ai_profiles (string filename)
            profile.binary = file.get_value (name, "binary");
            if (file.has_key (name, "args"))
                profile.args = file.get_value (name, "args");
+           else
+               profile.args = null; // bgo#696474
            profile.easy_options = load_options (file, name, "easy");
            profile.normal_options = load_options (file, name, "normal");
            profile.hard_options = load_options (file, name, "hard");
diff --git a/src/chess-engine-cecp.vala b/src/chess-engine-cecp.vala
index 65bd5df..ddb8f78 100644
--- a/src/chess-engine-cecp.vala
+++ b/src/chess-engine-cecp.vala
@@ -4,7 +4,7 @@ public class ChessEngineCECP : ChessEngine
     private bool moving = false;
     private string[] options;
 
-    public ChessEngineCECP (string binary, string args, string[] options)
+    public ChessEngineCECP (string binary, string? args, string[] options)
     {
         base (binary, args);
         this.options = options;
diff --git a/src/chess-engine-uci.vala b/src/chess-engine-uci.vala
index 505b906..6a8dc4a 100644
--- a/src/chess-engine-uci.vala
+++ b/src/chess-engine-uci.vala
@@ -5,7 +5,7 @@ public class ChessEngineUCI : ChessEngine
     private string[] options;
     private bool waiting_for_move;
 
-    public ChessEngineUCI (string binary, string args, string[] options)
+    public ChessEngineUCI (string binary, string? args, string[] options)
     {
         base (binary, args);
         this.options = options;
diff --git a/src/chess-engine.vala b/src/chess-engine.vala
index ee49f87..42a7ac0 100644
--- a/src/chess-engine.vala
+++ b/src/chess-engine.vala
@@ -30,7 +30,7 @@ public abstract class ChessEngine : Object
         }
     }
 
-    public ChessEngine (string binary, string args)
+    public ChessEngine (string binary, string? args)
     {
         this.binary = binary;
         this.args = args;