func (a *api) outputPrelude(f simprogtext.SimProgFile) {
	f.AddLine("package " + a.PackageName)
	f.AddLineIndent("import (")
	f.AddLine(`"fmt"`)
	f.AddLine(`"github.com/d-s-d/vesupro"`)
	f.AddLineUnindent(")")
}
func (a *api) outputDispatchers(f simprogtext.SimProgFile) {
	mCallParam := simprogtext.NewSimpleVar("mc")
	errVar := simprogtext.NewSimpleVar("err")
	argsVar := simprogtext.NewSimpleVar("arg")
	rcvVar := simprogtext.NewSimpleVar("r")

	for rcvTypeName, methods := range a.Methods {

		f.AddLineIndent(
			"func (%s *%s) Dispatch(%s *vesupro.MethodCall) "+
				"(vesupro.VesuproObject, error) {",
			rcvVar.VarName(), rcvTypeName, mCallParam.VarName())
		f.AddLine("var %s error", errVar.VarName())
		f.AddLine("%s := %s.Arguments", argsVar.VarName(),
			mCallParam.VarName())

		f.AddLine("switch %s.Name {", mCallParam.VarName())

		for _, _m := range methods {
			m := (*method)(_m)
			f.AddLineIndent("case %q:", m.Name)
			m.outputCall(f, mCallParam, argsVar, errVar, rcvVar,
				[]string{"nil"})
			f.Unindent()
		}

		f.AddLineIndent("default:")
		f.AddLine(`return nil,fmt.Errorf("Unknown function %%s.", %s.Name)`,
			mCallParam.VarName())
		f.AddLineUnindent("}") // switch
		f.AddLineUnindent("}") // DispatchCall function
	}
}
func outputCheckErrorReturn(f simprogtext.SimProgFile,
	errVar simprogtext.Var, nilVals []string) {
	retArgs := make([]string, len(nilVals)+1)
	copy(retArgs, nilVals)
	retArgs[len(nilVals)] = errVar.VarName()

	f.AddLineIndent("if %s != nil {", errVar.VarName())
	f.AddLine("return %s", strings.Join(retArgs, ", "))
	f.AddLineUnindent("}")
}
func (m *method) outputCall(f simprogtext.SimProgFile,
	mCallVar, argsVar, errVar, rcvVar simprogtext.Var,
	nilRetVals []string) error {
	paramVars := make([]simprogtext.DynSSAVar, len(m.Params))
	finalParams := make([]string, len(m.Params))

	f.AddLineIndent("if len(%s.Arguments) != %d {", mCallVar.VarName(),
		len(m.Params))
	f.AddLine(
		`fmt.Errof("Method \"%s\": Wrong number of arguments: %%d (want: %d)",`+
			`len(%s))`, m.Name, len(m.Params), argsVar.VarName())

	f.AddLineUnindent("}")

	var err error
	for i, param := range m.Params {
		paramVars[i] = simprogtext.NewDynSSAVar(fmt.Sprintf(
			"param_%d", param.Position), "")
		// parse Argument
		err = (*parameter)(param).OutputParseArgument(f, paramVars[i],
			simprogtext.NewSimpleVar(fmt.Sprintf("%s[%d]", argsVar.VarName(),
				i)), errVar)

		// go sucks
		if err != nil {
			return err
		}

		// check error
		outputCheckErrorReturn(f, errVar, nilRetVals)
	}

	for i, param := range m.Params {
		if param.IsStruct {
			finalParams[i] = paramVars[i].VarName()
		} else {
			finalParams[i] = fmt.Sprintf("%s(%s)", param.TypeName,
				paramVars[i].VarName())
		}
	}

	f.AddLine("return %s.%s(%s)", rcvVar.VarName(), m.Name,
		strings.Join(finalParams, ", "))

	return nil
}