Oh Thanks Matt, when Ian explained to me, I didn't think it'd work, but on
seeing your code illustration, I now think it works perfectly for *this*
case.
Just that this function approach will break if there are many base class
member fields that need to be accessed, as type methods can access them
internally, under the encapsulation. But that's a different story...
Thanks again *everyone*!
On Tue, Jan 2, 2018 at 10:26 AM, <matthewju...@gmail.com> wrote:
> You want different tokenizer types to be used in the same WalkBody
> implementation. Interfaces abstract the implementation from the calling
> computation.
>
> I think Ian did answer your question.
>
> type TokenVisitor interface {
> VisitToken()
> }
>
> func WalkBody(of TokenVisitor) {
> // here you call of.VisitToken()
> }
>
> type MyTokenizer1 struct {
> *html.Tokenizer
> }
>
> func (the MyTokenizer1) VisitToken() {
>
> }
>
> type MyTokenizer2 struct {
> *html.Tokenizer
> }
>
> func (the MyTokenizer2) VisitToken() {
>
> }
>
> // call WalkBody somewhere with either MyTokenizer1 or MyTokenizer2
>
> When I wanted to write one list of tests for two different set types I
> added set.go and set_test.go here: https://github.com/pciet/
> pathsetbenchmark
>
> Matt
>
> On Tuesday, January 2, 2018 at 8:45:56 AM UTC-6, Tong Sun wrote:
>>
>>
>>
>> On Mon, Jan 1, 2018 at 9:46 PM, Tong Sun <sunto...@gmail.com> wrote:
>>
>>> Hi,
>>>
>>> I think I generally understand how embedding (
>>> https://golang.org/doc/effective_go.html#embedding) works in GO.
>>> However, when it comes to the following problem, I'm at lost again.
>>>
>>> I'm trying to extend the `html.Tokenizer` with new methods of my own:
>>>
>>> type MyTokenizer struct {
>>> html.Tokenizer
>>> }
>>>
>>>
>>> func NewMyTokenizer(i io.Reader) *MyTokenizer {
>>> z := html.NewTokenizer(i)
>>> return *MyTokenizer(z)
>>> return &MyTokenizer{z}
>>> }
>>>
>>>
>>>
>>> so code like
>>>
>>> z := html.NewTokenizer(body)
>>> ...
>>> func parseBody(z *html.Tokenizer) {
>>> tt := z.Next()
>>> ...
>>> testt := z.Token()
>>> ...
>>>
>>>
>>> can become:
>>>
>>> z := NewMyTokenizer(body)
>>> ...
>>> func (z *MyTokenizer) parseBody() {
>>> tt := z.Next()
>>> ...
>>>
>>> testt := z.Token()
>>> ...
>>>
>>>
>>>
>>>
>>> However, I'm really struggling to make it work as I was expected.
>>>
>>> Somebody help please, what's the proper way to extend a type with new
>>> methods of my own, while still able to access all existing methods?
>>>
>>
>>
>> Thanks to Jason Phillips' help, the above part is solved:
>>
>> type MyTokenizer struct {
>> *html.Tokenizer
>> }
>>
>> func NewMyTokenizer(i io.Reader) *MyTokenizer {
>> z := html.NewTokenizer(i)
>> return &MyTokenizer{z}
>> }
>>
>> What's remaining is,
>>
>> Further more, how to extend the above even further? --
>>>
>>> - I plan to define an interface with a new method `WalkBody()`, in which
>>> a "virtual" method of `VisitToken()` is used.
>>> - Then I plan to define two different type of MyTokenizer, with their
>>> own `VisitToken()` methods, so the same `WalkBody()` method defined in
>>> MyTokenizer will behave differently for those two different types.
>>>
>>> How to architect above in Go?
>>>
>>
>> I've found this afterward,
>>
>> http://hackthology.com/object-oriented-inheritance-in-go.html
>>
>> I'll digest and try it out, and see how that can solve the above problem,
>> because it builds bottom up (not mid-way up).
>>
>> Meanwhile, if someone can explain how to think and solve such problem in
>> Go, that'd be much appreciated. Only at the architectural level would be
>> fine for me, I can try it out myself. The real problem to me is that I have
>> a *systematic *thinking in OO how to solve such kind of inherit &
>> enhance problem, and there is a *practical *implementation in place for
>> me, the virtual functions. But when it comes to Go, I still need help for
>> how to *think*, and how to *do*.
>>
>> Thanks!
>>
>>
>>>
>>> For your convenience, you can use this as an easy start, when
>>> demonstrating your architectural solution.
>>> https://github.com/suntong/lang/blob/master/lang/Go/src/xml/
>>> htmlParserTokens.go
>>>
>>>
>>> Thx a lot!
>>>
>>>
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>>
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