From 28e08b23e27e9119e47d4425e3e6260cdcf31263 Mon Sep 17 00:00:00 2001
From: Richard Heck <rgheck@comcast.net>
Date: Thu, 13 Jan 2011 21:19:14 +0000
Subject: [PATCH] Fix bug #7044: Better error messages when modules are
 unavailable. Patch from Julien Rioux, modified by me.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@37207 a592a061-630c-0410-9148-cb99ea01b6c8
---
 src/ModuleList.cpp | 15 +++++++++++++--
 src/ModuleList.h   |  4 ++++
 src/TextClass.cpp  | 12 ++++++++----
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/src/ModuleList.cpp b/src/ModuleList.cpp
index 4ed97de914..a965871002 100644
--- a/src/ModuleList.cpp
+++ b/src/ModuleList.cpp
@@ -45,6 +45,17 @@ LyXModule::LyXModule(string const & n, string const & i,
 }
 
 
+vector<string> LyXModule::prerequisites() const {
+#ifdef TEX2LYX
+	return vector<string>();
+#else
+	if (!checked_)
+		isAvailable();
+	return prerequisites_;
+#endif
+}
+
+
 bool LyXModule::isAvailable() const {
 #ifdef TEX2LYX
 	return true;
@@ -54,16 +65,16 @@ bool LyXModule::isAvailable() const {
 	if (checked_)
 		return available_;
 	checked_ = true;
+	available_ = true;
 	//check whether all of the required packages are available
 	vector<string>::const_iterator it  = package_list_.begin();
 	vector<string>::const_iterator end = package_list_.end(); 
 	for (; it != end; ++it) {
 		if (!LaTeXFeatures::isAvailable(*it)) {
 			available_ = false;
-			return available_;
+			prerequisites_.push_back(*it);
 		}
 	}
-	available_ = true;
 	return available_;
 #endif
 }
diff --git a/src/ModuleList.h b/src/ModuleList.h
index c9a6f1f4d7..d3abef913a 100644
--- a/src/ModuleList.h
+++ b/src/ModuleList.h
@@ -58,6 +58,8 @@ public:
 	          std::string const & catgy);
 	/// whether the required packages are available
 	bool isAvailable() const;
+	/// the missing prerequisites, if any
+	std::vector<std::string> prerequisites() const;
 	///
 	std::string const & getName() const { return name_; }
 	///
@@ -108,6 +110,8 @@ private:
 	mutable bool checked_;
 	///
 	mutable bool available_;
+	///
+	mutable std::vector<std::string> prerequisites_;
 };
 
 typedef std::vector<LyXModule> LyXModuleList;
diff --git a/src/TextClass.cpp b/src/TextClass.cpp
index a43ad9edf9..750d554001 100644
--- a/src/TextClass.cpp
+++ b/src/TextClass.cpp
@@ -1308,11 +1308,15 @@ DocumentClass & DocumentClassBundle::makeDocumentClass(
 			continue;
 		}
 		if (!lm->isAvailable()) {
+			docstring const prereqs = from_utf8(getStringFromVector(lm->prerequisites(), "\n\t"));
 			docstring const msg =
-				bformat(_("The module %1$s requires a package that is\n"
-				"not available in your LaTeX installation, or a converter\n"
-				"you have not installed. LaTeX output may not be possible.\n"), 
-				from_utf8(modName));
+				bformat(_("The module %1$s requires a package that is not\n"
+					"available in your LaTeX installation, or a converter that\n"
+					"you have not installed. LaTeX output may not be possible.\n"
+					"Missing prerequisites:\n"
+						"\t%2$s\n"
+					"See section 3.1.2.3 of the User's Guide for more information."),
+				from_utf8(modName), prereqs);
 			frontend::Alert::warning(_("Package not available"), msg);
 		}
 		FileName layout_file = libFileSearch("layouts", lm->getFilename());