Set empty collections to nil value #14
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Given a type:
```golang
type Foo struct {
Bar []string
}
```
When `Foo.Bar` is uninitialised/ `nil`, we Marshall with a Len of
0. When we then Unmarshall we initialise a `[]string` of length 0.
The problem here is that a `nil` slice and a slice of `len()` 0 are two
different things. Thus, when we try:
```golang
in := new(Foo)
in.Marshall(buf)
out := new(Foo)
out.Unmarshall(buf)
```
our types don't match up.
By testing whether `f.Len() == 0` and setting `Foo.Bar` as the nil
value, rather than anything else, we know our collection should be nil.
Of course, this wont work if the collection _should_ be of length 0.
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Note: we could use negative lengths to signify that a slice (etc.) should be nil, and use 0 to signify a 0 length slice, but our format uses We could just as easily change this, but all current serialised stuff will no longer unmarshall. |
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Given a type:
When
Foo.Baris uninitialised/nil, we Marshall with a Len of 0. When we then Unmarshall we initialise a[]stringof length 0.The problem here is that a
nilslice and a slice oflen()0 are two different things. Thus, when we try:our types don't match up.
By testing whether
f.Len() == 0and settingFoo.Baras the nil value, rather than anything else, we know our collection should be nil.Of course, this wont work if the collection should be of length 0.