class WIN32OLE::Param

Returns WIN32OLE_PARAM object which represents OLE parameter information. 1st argument should be WIN32OLE_METHOD object. 2nd argument ‘n’ is n-th parameter of the method specified by 1st argument.

tobj = WIN32OLE_TYPE.new('Microsoft Scripting Runtime', 'IFileSystem')
method = WIN32OLE_METHOD.new(tobj, 'CreateTextFile')
param = WIN32OLE_PARAM.new(method, 2) # => #<WIN32OLE_PARAM:Overwrite=true>

static VALUE
foleparam_initialize(VALUE self, VALUE olemethod, VALUE n)
{
    int idx;
    if (!rb_obj_is_kind_of(olemethod, cWIN32OLE_METHOD)) {
        rb_raise(rb_eTypeError, "1st parameter must be WIN32OLE_METHOD object");
    }
    idx = RB_FIX2INT(n);
    return oleparam_ole_param(self, olemethod, idx);
}

Returns default value. If the default value does not exist, this method returns nil.

tobj = WIN32OLE_TYPE.new('Microsoft Excel 9.0 Object Library', 'Workbook')
method = WIN32OLE_METHOD.new(tobj, 'SaveAs')
method.params.each do |param|
  if param.default
    puts "#{param.name} (= #{param.default})"
  else
    puts "#{param}"
  end
end

The above script result is following:
    Filename
    FileFormat
    Password
    WriteResPassword
    ReadOnlyRecommended
    CreateBackup
    AccessMode (= 1)
    ConflictResolution
    AddToMru
    TextCodepage
    TextVisualLayout

static VALUE
foleparam_default(VALUE self)
{
    struct oleparamdata *pparam;
    TypedData_Get_Struct(self, struct oleparamdata, &oleparam_datatype, pparam);
    return ole_param_default(pparam->pTypeInfo, pparam->method_index,
                             pparam->index);
}

Returns true if the parameter is input.

tobj = WIN32OLE_TYPE.new('Microsoft Excel 9.0 Object Library', 'Workbook')
method = WIN32OLE_METHOD.new(tobj, 'SaveAs')
param1 = method.params[0]
puts param1.input? # => true

static VALUE
foleparam_input(VALUE self)
{
    struct oleparamdata *pparam;
    TypedData_Get_Struct(self, struct oleparamdata, &oleparam_datatype, pparam);
    return ole_param_flag_mask(pparam->pTypeInfo, pparam->method_index,
                               pparam->index, PARAMFLAG_FIN);
}

Returns the parameter name with class name. If the parameter has default value, then returns name=value string with class name.

static VALUE
foleparam_inspect(VALUE self)
{
    VALUE detail = foleparam_name(self);
    VALUE defval = foleparam_default(self);
    if (defval != Qnil) {
        rb_str_cat2(detail, "=");
        rb_str_concat(detail, rb_inspect(defval));
    }
    return make_inspect("WIN32OLE_PARAM", detail);
}

Returns name.

tobj = WIN32OLE_TYPE.new('Microsoft Excel 9.0 Object Library', 'Workbook')
method = WIN32OLE_METHOD.new(tobj, 'SaveAs')
param1 = method.params[0]
puts param1.name # => Filename

static VALUE
foleparam_name(VALUE self)
{
    return rb_ivar_get(self, rb_intern("name"));
}

Returns OLE type of WIN32OLE_PARAM object(parameter of OLE method).

tobj = WIN32OLE_TYPE.new('Microsoft Excel 9.0 Object Library', 'Workbook')
method = WIN32OLE_METHOD.new(tobj, 'SaveAs')
param1 = method.params[0]
puts param1.ole_type # => VARIANT

static VALUE
foleparam_ole_type(VALUE self)
{
    struct oleparamdata *pparam;
    TypedData_Get_Struct(self, struct oleparamdata, &oleparam_datatype, pparam);
    return ole_param_ole_type(pparam->pTypeInfo, pparam->method_index,
                              pparam->index);
}

Returns detail information of type of argument.

tobj = WIN32OLE_TYPE.new('Microsoft Excel 9.0 Object Library', 'IWorksheetFunction')
method = WIN32OLE_METHOD.new(tobj, 'SumIf')
param1 = method.params[0]
p param1.ole_type_detail # => ["PTR", "USERDEFINED", "Range"]

static VALUE
foleparam_ole_type_detail(VALUE self)
{
    struct oleparamdata *pparam;
    TypedData_Get_Struct(self, struct oleparamdata, &oleparam_datatype, pparam);
    return ole_param_ole_type_detail(pparam->pTypeInfo, pparam->method_index,
                                     pparam->index);
}

Returns true if argument is optional.

tobj = WIN32OLE_TYPE.new('Microsoft Excel 9.0 Object Library', 'Workbook')
method = WIN32OLE_METHOD.new(tobj, 'SaveAs')
param1 = method.params[0]
puts "#{param1.name} #{param1.optional?}" # => Filename true

static VALUE
foleparam_optional(VALUE self)
{
    struct oleparamdata *pparam;
    TypedData_Get_Struct(self, struct oleparamdata, &oleparam_datatype, pparam);
    return ole_param_flag_mask(pparam->pTypeInfo, pparam->method_index,
                               pparam->index, PARAMFLAG_FOPT);
}

Returns true if argument is output.

tobj = WIN32OLE_TYPE.new('Microsoft Internet Controls', 'DWebBrowserEvents')
method = WIN32OLE_METHOD.new(tobj, 'NewWindow')
method.params.each do |param|
  puts "#{param.name} #{param.output?}"
end

The result of above script is following:
  URL false
  Flags false
  TargetFrameName false
  PostData false
  Headers false
  Processed true

static VALUE
foleparam_output(VALUE self)
{
    struct oleparamdata *pparam;
    TypedData_Get_Struct(self, struct oleparamdata, &oleparam_datatype, pparam);
    return ole_param_flag_mask(pparam->pTypeInfo, pparam->method_index,
                               pparam->index, PARAMFLAG_FOUT);
}

Returns true if argument is return value.

tobj = WIN32OLE_TYPE.new('DirectX 7 for Visual Basic Type Library',
                         'DirectPlayLobbyConnection')
method = WIN32OLE_METHOD.new(tobj, 'GetPlayerShortName')
param = method.params[0]
puts "#{param.name} #{param.retval?}"  # => name true

static VALUE
foleparam_retval(VALUE self)
{
    struct oleparamdata *pparam;
    TypedData_Get_Struct(self, struct oleparamdata, &oleparam_datatype, pparam);
    return ole_param_flag_mask(pparam->pTypeInfo, pparam->method_index,
                               pparam->index, PARAMFLAG_FRETVAL);
}