* Debug levels. Use `--verbose / -v LEVEL' to display only messages

  up to the given verbosity levels.  These currently are:

    lvlError = 0, 
    lvlNormal = 5,
    lvlDebug = 10,
    lvlDebugMore = 15

  although only lvlError and lvlDebug are actually used right now.

8 files changed, 68 insertions, 25 deletions

diff --git a/src/fix.cc b/src/fix.cc
index afa0167ecd..8463c0ddb1 100644
--- a/src/fix.cc
+++ b/src/fix.cc
@@ -310,6 +310,16 @@ void run(Strings args)
                 throw UsageError(format("argument required in `%1%'") % arg);
             state.searchDirs.push_back(*it++);
         }
+        else if (arg == "--verbose" || arg == "-v") {
+            if (it == args.end()) throw UsageError(
+                format("`%1%' requires an argument") % arg);
+            istringstream str(*it++);
+            int lvl;
+            str >> lvl;
+            if (str.fail()) throw UsageError(
+                format("`%1%' requires an integer argument") % arg);
+            verbosity = (Verbosity) lvl;
+        }
         else if (arg[0] == '-')
             throw UsageError(format("unknown flag `%1%`") % arg);
         else
diff --git a/src/nix.cc b/src/nix.cc
index e088542276..f672c42a80 100644
--- a/src/nix.cc
+++ b/src/nix.cc
@@ -1,4 +1,5 @@
 #include <iostream>
+#include <sstream>
 
 #include "globals.hh"
 #include "normalise.hh"
@@ -278,10 +279,9 @@ void run(Strings args)
     Strings opFlags, opArgs;
     Operation op = 0;
 
-    for (Strings::iterator it = args.begin();
-         it != args.end(); it++)
+    for (Strings::iterator it = args.begin(); it != args.end(); )
     {
-        string arg = *it;
+        string arg = *it++;
 
         Operation oldOp = op;
 
@@ -307,6 +307,16 @@ void run(Strings args)
             op = opVerify;
         else if (arg == "--path" || arg == "-p")
             pathArgs = true;
+        else if (arg == "--verbose" || arg == "-v") {
+            if (it == args.end()) throw UsageError(
+                format("`%1%' requires an argument") % arg);
+            istringstream str(*it++);
+            int lvl;
+            str >> lvl;
+            if (str.fail()) throw UsageError(
+                format("`%1%' requires an integer argument") % arg);
+            verbosity = (Verbosity) lvl;
+        }
         else if (arg[0] == '-')
             opFlags.push_back(arg);
         else
diff --git a/src/normalise.cc b/src/normalise.cc
index f463457e4a..6ce73d1acd 100644
--- a/src/normalise.cc
+++ b/src/normalise.cc
@@ -26,8 +26,7 @@ typedef set<FSId> FSIdSet;
 
 Slice normaliseFState(FSId id, FSIdSet pending)
 {
-    debug(format("normalising fstate %1%") % (string) id);
-    Nest nest(true);
+    Nest nest(lvlDebug, format("normalising fstate %1%") % (string) id);
 
     /* Try to substitute $id$ by any known successors in order to
        speed up the rewrite process. */
@@ -177,8 +176,7 @@ Slice normaliseFState(FSId id, FSIdSet pending)
 
 void realiseSlice(const Slice & slice, FSIdSet pending)
 {
-    debug(format("realising slice"));
-    Nest nest(true);
+    Nest nest(lvlDebug, format("realising slice"));
 
     /* Perhaps all paths already contain the right id? */
 
diff --git a/src/shared.cc b/src/shared.cc
index bfd7498de1..75145f6db2 100644
--- a/src/shared.cc
+++ b/src/shared.cc
@@ -1,4 +1,5 @@
 #include <iostream>
+#include <cctype>
 
 extern "C" {
 #include <aterm2.h>
@@ -32,7 +33,12 @@ static void initAndRun(int argc, char * * argv)
         string arg = *it;
         if (arg.length() > 2 && arg[0] == '-' && arg[1] != '-') {
             for (unsigned int i = 1; i < arg.length(); i++)
-                args.insert(it, (string) "-" + arg[i]);
+                if (isalpha(arg[i]))
+                    args.insert(it, (string) "-" + arg[i]);
+                else {
+                    args.insert(it, string(arg, i));
+                    break;
+                }
             it = args.erase(it);
         } else it++;
     }
@@ -50,18 +56,21 @@ int main(int argc, char * * argv)
     try {
         initAndRun(argc, argv);
     } catch (UsageError & e) {
-        cerr << format(
-            "error: %1%\n"
-            "Try `%2% --help' for more information.\n")
-            % e.what() % programId;
+        msg(lvlError, 
+            format(
+                "error: %1%\n"
+                "Try `%2% --help' for more information.")
+            % e.what() % programId);
         return 1;
     } catch (Error & e) {
-        cerr << format("error: %1%\n") % e.msg();
+        msg(lvlError, format("error: %1%") % e.msg());
         return 1;
     } catch (exception & e) {
-        cerr << format("error: %1%\n") % e.what();
+        msg(lvlError, format("error: %1%") % e.what());
         return 1;
     }
 
     return 0;
 }
+
+
diff --git a/src/store.cc b/src/store.cc
index 013bd2e2a7..50932d8062 100644
--- a/src/store.cc
+++ b/src/store.cc
@@ -168,7 +168,7 @@ string expandId(const FSId & id, const string & target,
     const string & prefix, FSIdSet pending)
 {
     debug(format("expanding %1%") % (string) id);
-    Nest nest(true);
+    Nest nest(lvlDebug, format("expanding %1%") % (string) id);
 
     Strings paths;
 
diff --git a/src/test.cc b/src/test.cc
index 6b567abe03..a2431273e7 100644
--- a/src/test.cc
+++ b/src/test.cc
@@ -12,8 +12,7 @@
 
 void realise(FSId id)
 {
-    debug(format("TEST: realising %1%") % (string) id);
-    Nest nest(true);
+    Nest nest(lvlDebug, format("TEST: realising %1%") % (string) id);
     Slice slice = normaliseFState(id);
     realiseSlice(slice);
 }
diff --git a/src/util.cc b/src/util.cc
index a16643022a..8510bb7a63 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -130,13 +130,20 @@ void deletePath(string path)
 }
 
 
+Verbosity verbosity = lvlNormal;
+
 static int nestingLevel = 0;
 
 
-Nest::Nest(bool nest)
+Nest::Nest(Verbosity level, const format & f)
 {
-    this->nest = nest;
-    if (nest) nestingLevel++;
+    if (level > verbosity)
+        nest = false;
+    else {
+        msg(level, f);
+        nest = true;
+        nestingLevel++;
+    }
 }
 
 
@@ -146,8 +153,9 @@ Nest::~Nest()
 }
 
 
-void msg(const format & f)
+void msg(Verbosity level, const format & f)
 {
+    if (level > verbosity) return;
     string spaces;
     for (int i = 0; i < nestingLevel; i++)
         spaces += "|   ";
@@ -157,7 +165,7 @@ void msg(const format & f)
 
 void debug(const format & f)
 {
-    msg(format("debug: %1%") % f.str());
+    msg(lvlDebug, format("debug: %1%") % f.str());
 }
 
 
diff --git a/src/util.hh b/src/util.hh
index 8b23bee00b..6d87898b5d 100644
--- a/src/util.hh
+++ b/src/util.hh
@@ -72,17 +72,26 @@ void deletePath(string path);
 
 /* Messages. */
 
+typedef enum { 
+    lvlError = 0, 
+    lvlNormal = 5,
+    lvlDebug = 10,
+    lvlDebugMore = 15
+} Verbosity;
+
+extern Verbosity verbosity; /* supress msgs > this */
+
 class Nest
 {
 private:
     bool nest;
 public:
-    Nest(bool nest);
+    Nest(Verbosity level, const format & f);
     ~Nest();
 };
 
-void msg(const format & f);
-void debug(const format & f);
+void msg(Verbosity level, const format & f);
+void debug(const format & f); /* shorthand */
 
 
 /* Wrappers arount read()/write() that read/write exactly the