From d3ebaa37fa9d06ca60017d9bc6dc213518cc1fc9 Mon Sep 17 00:00:00 2001
From: Levi Armstrong <levi.armstrong@gmail.com>
Date: Mon, 2 Oct 2023 09:21:21 -0500
Subject: [PATCH] Update composite instruction user data to align with gazebo
 user data variant

---
 .../composite_instruction.h                         | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/tesseract_command_language/include/tesseract_command_language/composite_instruction.h b/tesseract_command_language/include/tesseract_command_language/composite_instruction.h
index 268a98d4a44..859d20beb04 100644
--- a/tesseract_command_language/include/tesseract_command_language/composite_instruction.h
+++ b/tesseract_command_language/include/tesseract_command_language/composite_instruction.h
@@ -71,8 +71,17 @@ class CompositeInstruction
   EIGEN_MAKE_ALIGNED_OPERATOR_NEW
   // LCOV_EXCL_STOP
 
-  /** User Data */
-  using UserDataVariant = std::variant<double, long, std::size_t, std::string, tesseract_common::AnyPoly>;
+  /**
+   * @brief Alias for a variant that can hold various types of data.
+   * @details The first type of the variant is std::monostate in order to prevent
+   * default-constructed variants from holding a type (a default-constructed
+   * variant is returned when a user calls CompositeInstruction::UserData with a key that
+   * doesn't exist for the CompositeInstruction. In this case, since the key doesn't
+   * exist, the variant that is returned shouldn't hold any types - an
+   * "empty variant" should be returned for keys that don't exist)
+   */
+  using UserDataVariant =
+      std::variant<std::monostate, int, long, float, double, std::string, bool, std::size_t, tesseract_common::AnyPoly>;
   using UserData = std::unordered_map<std::string, UserDataVariant>;
 
   /** value_type */