On Fri, Dec 3, 2010 at 5:08 PM, Evan Nemerson <e...@coeus-group.com> wrote:
> On Fri, 2010-12-03 at 15:38 -0800, Anatol Pomozov wrote:
>> Hi,
>>
>> I have a class that contains a field and method with the same name,
>> and Valac does not like it. What is the reason? Other languages
>> (C#/Java) allow it. You have to use () for method so you know whether
>> you access method or field.
>
> I'm not a C# or Java programmer, so feel free to correct me if I'm wrong
> but...
>
> Java doesn't have delegates. In this example, what is X?
Ah, delegates, functions that act as variables. Now it a little bit clearer.
>
> public class Foo {
> public boolean stop = true;
>
> public boolean stop () {
> return true;
> }
>
> public Foo () {
> var X = this.stop;
> }
> }
This example does not work. valac 0.11 complains with quite weird message
a.vala:11.7-11.18: error: Assignment: Cannot convert from `Foo.stop'
to `Foo.stop'
var x = this.stop;
We cannot use var - we need to declare Delegate type here. Something like
MyDelegateType x = this.stop;
But in this case it is clear that we want function. We cannot assign
field/property to a delegate, isn't it?
Sorry for stubbornness - I learn Vala and trying to illuminate all
dark corners. I am looking for an example that clearly shows why we
cannot have field/method with the same name.
> Actually, now that I think about it, I don't think Java does type
> inferencing either.
It is planned for Java7.
>
> In addition to type inferencing issues, this could cause problems with
> generics, and would generally be a pain to read.
Not sure what do you mean here.
>
> C# doesn't allow this either. AFAIK, in C# you can overload methods so
> that the most appropriate method is called, but you can't have a method
> and a property with the same name. Example:
>
> class Foo {
> bool stop () {
> return true;
> }
>
> // No problem
> bool stop (bool a) {
> return false;
> }
>
> // Problem
> bool stop = false;
>
> public static void Main () {
> var foo = new Foo ();
> }
> }
>
> Overloading methods is a separate issue, which Aleksander Wabik already
> explained.
>
>> anatol:vala $ valac a.vala
>> a.vala:4.3-4.21: error: `Foo' already contains a definition for `stop'
>> public boolean stop() {
>> ^^^^^^^^^^^^^^^^^^^
>> a.vala:2.3-2.21: note: previous definition of `stop' was here
>> public boolean stop = true;
>> ^^^^^^^^^^^^^^^^^^^
>> Compilation failed: 1 error(s), 0 warning(s)
>
> Amusingly, this is basically the same error message as you get in C# (at
> least from mcs):
>
> test.cs(12,8): error CS0102: The type `Foo' already contains a
> definition for `stop'
> test.cs(2,8): (Location of the symbol related to previous error)
> Compilation failed: 1 error(s), 0 warnings
Oops, my statement that it works in C# is wrong. I was looking at
incorrect C# example.
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