diff --git a/src/error-demo/error-demo.cc b/src/error-demo/error-demo.cc
index 8fb20d38c..fdb574b25 100644
--- a/src/error-demo/error-demo.cc
+++ b/src/error-demo/error-demo.cc
@@ -22,21 +22,25 @@ int main()
     // created.
 
     // ProgramError takes name, description, and an optional hint.
-    printErrorInfo( ProgramError()
-                    .name("name")
-                    .description("error description")
-                    .nohint()
-                  );
+    printErrorInfo(
+        ErrorInfo::ProgramError("name",
+                                "error description",
+                                std::nullopt));
 
     // ProgramWarning takes name, description, and an optional hint.
     // The hint is in the form of a hintfmt class, which wraps boost::format(),
     // and makes all the substituted text yellow.
-    printErrorInfo( ProgramWarning()
-                    .name("warning name")
-                    .description("warning description")
-                    // the templated value, 'warning', is automatically colored yellow.
-                    .hint(hintfmt("there was a %1%", "warning")) 
-                  );
+    printErrorInfo(
+        ErrorInfo::ProgramWarning("name",
+                                  "warning description",
+                                  std::optional(hintfmt("there was a %1%", "warning"))));
+
+    // printErrorInfo( ProgramWarning()
+    //                 .name("warning name")
+    //                 .description("warning description")
+    //                 // the templated value, 'warning', is automatically colored yellow.
+    //                 .hint(hintfmt("there was a %1%", "warning"))
+    //               );
 
     /*
       // some invalid errors:
@@ -63,25 +67,34 @@ int main()
     SymbolTable testTable;
     auto problem_symbol = testTable.create("problem");
 
-    printErrorInfo(NixLangWarning()
-                   .name("warning name")
-                   .description("warning description")
-                   .pos(Pos(problem_symbol, 40, 13))
-                   .linesOfCode(std::nullopt,
-                                "this is the problem line of code",
-                                std::nullopt)
-                   .hint(hintfmt("this hint has %1% templated %2%!!", "yellow" , "values")));
+    printErrorInfo(ErrorInfo::NixLangWarning(
+                       "warning name",
+                       "warning description",
+                       Pos(problem_symbol, 40, 13),
+                       std::nullopt,
+                       "this is the problem line of code",
+                       std::nullopt,
+                       hintfmt("this hint has %1% templated %2%!!", "yellow", "values")));
+
+    // // NixLangError is just the same as NixLangWarning, except for the Error
+    // // flag.
+    // printErrorInfo(NixLangError()
+    //                .name("error name")
+    //                .description("error description")
+    //                .pos(Pos(problem_symbol, 40, 13))
+    //                .linesOfCode(std::optional("previous line of code"),
+    //                             "this is the problem line of code",
+    //                             std::optional("next line of code"))
+    //                .hint(hintfmt("this hint has %1% templated %2%!!", "yellow", "values")));
+    printErrorInfo(ErrorInfo::NixLangError(
+                       "error name",
+                       "error description",
+                       Pos(problem_symbol, 40, 13),
+                       std::optional("previous line of code"),
+                       "this is the problem line of code",
+                       std::optional("next line of code"),
+                       hintfmt("this hint has %1% templated %2%!!", "yellow", "values")));
 
-    // NixLangError is just the same as NixLangWarning, except for the Error
-    // flag.
-    printErrorInfo(NixLangError()
-                   .name("error name")
-                   .description("error description")
-                   .pos(Pos(problem_symbol, 40, 13))
-                   .linesOfCode(std::optional("previous line of code"),
-                                "this is the problem line of code",
-                                std::optional("next line of code"))
-                   .hint(hintfmt("this hint has %1% templated %2%!!", "yellow", "values")));
 
     return 0;
 }
diff --git a/src/libutil/error.cc b/src/libutil/error.cc
index 8ab4a2dea..41fabbbcf 100644
--- a/src/libutil/error.cc
+++ b/src/libutil/error.cc
@@ -8,7 +8,43 @@ namespace nix
 
 std::optional<string> ErrorInfo::programName = std::nullopt;
 
-string showErrLine(ErrLine &errLine)
+ErrorInfo ErrorInfo::ProgramError(const string &name,
+                                  const string &description,
+                                  const std::optional<hintformat> &hf)
+{
+    return ProgramEI(elError, name, description, hf);
+}
+
+ErrorInfo ErrorInfo::ProgramWarning(const string &name,
+                                    const string &description,
+                                    const std::optional<hintformat> &hf)
+{
+    return ProgramEI(elWarning, name, description, hf);
+}
+
+
+
+ErrorInfo ErrorInfo::ProgramEI(ErrLevel level,
+                               const string &name,
+                               const string &description,
+                               const std::optional<hintformat> &hf)
+{
+    ErrorInfo ei(elError);
+    ei.name = name;
+    ei.description = description;
+    if (hf.has_value())
+        ei.hint = std::optional<string>(hf->str());
+    else
+        ei.hint = std::nullopt;
+    return ei;
+}
+
+
+
+
+
+
+string showErrLine(const ErrLine &errLine)
 {
     if (errLine.columnRange.has_value()) {
         return (format("(%1%:%2%)") % errLine.lineNumber % errLine.columnRange->start).str();
@@ -17,7 +53,7 @@ string showErrLine(ErrLine &errLine)
     };
 }
 
-void printCodeLines(string &prefix, NixCode &nixCode)
+void printCodeLines(const string &prefix, const NixCode &nixCode)
 {
 
     if (nixCode.errLine.has_value()) {
@@ -69,7 +105,7 @@ void printCodeLines(string &prefix, NixCode &nixCode)
 
 }
 
-void printErrorInfo(ErrorInfo &einfo)
+void printErrorInfo(const ErrorInfo &einfo)
 {
     int errwidth = 80;
     string prefix = "    ";
diff --git a/src/libutil/error.hh b/src/libutil/error.hh
index 57a9944be..a73b6639e 100644
--- a/src/libutil/error.hh
+++ b/src/libutil/error.hh
@@ -41,153 +41,8 @@ class NixCode
 public:
     std::optional<string> nixFile;
     std::optional<ErrLine> errLine;
-
-    ErrLine& ensureErrLine()
-    {
-        if (!this->errLine.has_value())
-            this->errLine = std::optional(ErrLine());
-        return *this->errLine;
-    }
 };
 
-// -------------------------------------------------
-// ErrorInfo.
-
-// Forward friend class declarations.    "builder classes"
-template <class T>
-class AddName;
-
-template <class T>
-class AddDescription;
-
-template <class T>
-class AddPos;
-
-template <class T>
-class AddLOC;
-
-// The error info class itself.
-class ErrorInfo
-{
-public:
-    ErrLevel level;
-    string name;
-    string description;
-    std::optional<NixCode> nixCode;
-    std::optional<string> hint;
-    ErrorInfo& GetEI()
-    {
-        return *this;
-    }
-
-    static std::optional<string> programName;
-
-    // give these access to the private constructor,
-    // when they are direct descendants (children but not grandchildren).
-    friend AddName<ErrorInfo>;
-    friend AddDescription<ErrorInfo>;
-    friend AddPos<ErrorInfo>;
-    friend AddLOC<ErrorInfo>;
-
-    NixCode& ensureNixCode()
-    {
-        if (!this->nixCode.has_value())
-            this->nixCode = std::optional(NixCode());
-        return *this->nixCode;
-    }
-protected:
-    // constructor is protected, so only the builder classes can create an ErrorInfo.
-    ErrorInfo(ErrLevel level)
-    {
-        this->level = level;
-    }
-};
-
-// Init as error
-class EIError : public ErrorInfo
-{
-protected:
-    EIError() : ErrorInfo(elError) {}
-};
-
-// Init as warning
-class EIWarning : public ErrorInfo
-{
-protected:
-    EIWarning() : ErrorInfo(elWarning) {}
-};
-
-// Builder class definitions.
-template <class T>
-class AddName : private T
-{
-public:
-    T& name(const std::string &name)
-    {
-        GetEI().name = name;
-        return *this;
-    }
-protected:
-    ErrorInfo& GetEI()
-    {
-        return T::GetEI();
-    }
-};
-
-template <class T>
-class AddDescription : private T
-{
-public:
-    T& description(const std::string &description)
-    {
-        GetEI().description = description;
-        return *this;
-    }
-protected:
-    ErrorInfo& GetEI()
-    {
-        return T::GetEI();
-    }
-};
-
-template <class T>
-class AddPos : private T
-{
-public:
-    template <class P>
-    T& pos(const P &aPos)
-    {
-        GetEI().ensureNixCode().nixFile = aPos.file;
-        GetEI().ensureNixCode().ensureErrLine().lineNumber = aPos.line;
-        GetEI().ensureNixCode().ensureErrLine().columnRange = { .start = aPos.column, .len = 1 };
-        return *this;
-    }
-protected:
-    ErrorInfo& GetEI()
-    {
-        return T::GetEI();
-    }
-};
-
-template <class T>
-class AddLOC : private T
-{
-public:
-    T& linesOfCode(std::optional<string> prevloc, string loc, std::optional<string> nextloc)
-    {
-        GetEI().ensureNixCode().ensureErrLine().prevLineOfCode = prevloc;
-        GetEI().ensureNixCode().ensureErrLine().errLineOfCode = loc;
-        GetEI().ensureNixCode().ensureErrLine().nextLineOfCode = nextloc;
-        return *this;
-    }
-protected:
-    ErrorInfo& GetEI()
-    {
-        return T::GetEI();
-    }
-};
-
-
 // ----------------------------------------------------------------
 // format for hints.  same as fmt, except templated values
 // are always in yellow.
@@ -229,7 +84,6 @@ public:
     friend class AddHint;
 private:
     format fmt;
-
 };
 
 template<typename... Args>
@@ -240,6 +94,143 @@ inline hintformat hintfmt(const std::string & fs, const Args & ... args)
     return f;
 }
 
+// -------------------------------------------------
+// ErrorInfo.
+class ErrorInfo
+{
+public:
+    ErrLevel level;
+    string name;
+    string description;
+    std::optional<NixCode> nixCode;
+    std::optional<string> hint;
+
+    static std::optional<string> programName;
+
+    static ErrorInfo ProgramError(const string &name,
+                                  const string &description,
+                                  const std::optional<hintformat> &hf);
+
+
+    static ErrorInfo ProgramWarning(const string &name,
+                                    const string &description,
+                                    const std::optional<hintformat> &hf);
+
+
+    template <class P>
+    static ErrorInfo NixLangError(const string &name,
+                                  const string &description,
+                                  const P &pos,
+                                  std::optional<string> prevloc,
+                                  string loc,
+                                  std::optional<string> nextloc,
+                                  const std::optional<hintformat> &hf)
+    {
+        return NixLangEI(elError, name, description, pos, prevloc, loc, nextloc, hf);
+    }
+
+
+    template <class P>
+    static ErrorInfo NixLangWarning(const string &name,
+                                    const string &description,
+                                    const P &pos,
+                                    std::optional<string> prevloc,
+                                    string loc,
+                                    std::optional<string> nextloc,
+                                    const std::optional<hintformat> &hf)
+    {
+        return NixLangEI(elWarning, name, description, pos, prevloc, loc, nextloc, hf);
+    }
+
+
+
+private:
+    template <class P>
+    static ErrorInfo NixLangEI(ErrLevel level,
+                               const string &name,
+                               const string &description,
+                               const P &pos,
+                               std::optional<string> prevloc,
+                               string loc,
+                               std::optional<string> nextloc,
+                               const std::optional<hintformat> &hf)
+    {
+        ErrorInfo ei(level);
+        ei.name = name;
+        ei.description = description;
+        if (hf.has_value())
+            ei.hint = std::optional<string>(hf->str());
+        else
+            ei.hint = std::nullopt;
+
+        ErrLine errline;
+        errline.lineNumber = pos.line;
+        errline.columnRange = { .start = pos.column, .len = 1 };
+        errline.prevLineOfCode = prevloc;
+        errline.errLineOfCode = loc;
+        errline.nextLineOfCode = nextloc;
+        NixCode nixcode;
+        nixcode.nixFile = pos.file;
+        nixcode.errLine = std::optional(errline);
+        ei.nixCode = std::optional(nixcode);
+
+        return ei;
+    }
+
+    static ErrorInfo ProgramEI(ErrLevel level,
+                               const string &name,
+                               const string &description,
+                               const std::optional<hintformat> &hf);
+
+
+
+    // constructor is protected, so only the builder classes can create an ErrorInfo.
+    ErrorInfo(ErrLevel level)
+    {
+        this->level = level;
+    }
+};
+
+/*
+template <class T>
+class AddPos : private T
+{
+public:
+    template <class P>
+    T& pos(const P &aPos)
+    {
+        GetEI().ensureNixCode().nixFile = aPos.file;
+        GetEI().ensureNixCode().ensureErrLine().lineNumber = aPos.line;
+        GetEI().ensureNixCode().ensureErrLine().columnRange = { .start = aPos.column, .len = 1 };
+        return *this;
+    }
+protected:
+    ErrorInfo& GetEI()
+    {
+        return T::GetEI();
+    }
+};
+
+template <class T>
+class AddLOC : private T
+{
+public:
+    T& linesOfCode(std::optional<string> prevloc, string loc, std::optional<string> nextloc)
+    {
+        GetEI().ensureNixCode().ensureErrLine().prevLineOfCode = prevloc;
+        GetEI().ensureNixCode().ensureErrLine().errLineOfCode = loc;
+        GetEI().ensureNixCode().ensureErrLine().nextLineOfCode = nextloc;
+        return *this;
+    }
+protected:
+    ErrorInfo& GetEI()
+    {
+        return T::GetEI();
+    }
+};
+*/
+
+/*
 // the template layer for adding a hint.
 template <class T>
 class AddHint : private T
@@ -261,11 +252,12 @@ protected:
         return T::GetEI();
     }
 };
+*/
 
 // --------------------------------------------------------
 // error types
 
-typedef AddName<
+/*typedef AddName<
         AddDescription<
         AddHint<
         EIError>>> ProgramError;
@@ -290,11 +282,12 @@ typedef AddName<
         EIWarning>>>>> NixLangWarning;
 
 
+*/
 // --------------------------------------------------------
 // error printing
 
 // just to cout for now.
-void printErrorInfo(ErrorInfo &einfo);
+void printErrorInfo(const ErrorInfo &einfo);
 
 }