I am working in the context of an ODM.
I have an update method, like this:
func Update(key string, valuePtr interface{}) error
Inside of this method I need to do a Get in order to get the old value,
compare the modified fields and update them, then insert the new object in
the database.
The problem is that inside the Update method I don't know what type
valuePtr is in order to make a second object and feed to the Get method,
and then if I call the Get method with an interface{} object it will crash
because it can't Unmarshal (objects are kept as json in the database).
On Tuesday, August 2, 2016 at 11:26:01 AM UTC+3, Dave Cheney wrote:
>
> Hypothetically, if there was a syntax in Go that did this, what would you
> do next ? In other words, what is the problem you are trying to solve that
> has lead you to needing this feature?
>
> On Tuesday, 2 August 2016 18:18:05 UTC+10, Rayland wrote:
>>
>> I basically need something like this:
>>
>> var obj = &Person{Name: "John"} // I don't know what type obj will be
>> everytime
>> var newObj interface{}
>>
>> initNewObj(obj) // now newObj is an empty object of type *Person
>>
>>
>>
>>
>> On Tuesday, August 2, 2016 at 10:21:01 AM UTC+3, Dave Cheney wrote:
>>>
>>> TL;DR a shallow copy is easy, but it's almost never what you want.
>>>
>>> https://play.golang.org/p/wpWN3Znop8
>>>
>>> Needing to copy an arbitrary value is usually an anti pattern as values
>>> can contain references to other values, which contain references to other
>>> values, which contain references to other values, sometimes leading back to
>>> the previous values.
>>>
>>> On Tuesday, 2 August 2016 17:13:21 UTC+10, Rayland wrote:
>>>>
>>>> Let's say I have an object A of some type. Is there a way to create a
>>>> new object B with the same type as A without knowing the type of A in
>>>> advance?
>>>>
>>>
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