Make checkpoint a struct

[Charleslee522]

Now, checkpoint type is string so when we want to use source or target, we have to call ParseCheckpoint method. And checkpoint is used frequently, performance is important. I think if we define the Checkpoint struct and define related methods then it would be helpful for both performance and code quality.

type Checkpoint struct {
  Source string
  Target string
}

[leejames00]

If Checkpoint is struct, Source and Target types should be hash, not string.. am i right?

[Charleslee522]

@leejames00 It would be better :)

[anarcher]

Maybe it can be another approach... How about it? But I am not sure that it makes to improve performance. ~_~

type Checkpoint struct {
    Subtracted string // or Hash
    Added string // or Hash 
}

[outsideris]

What is another approach? I didn't get it.

[Charleslee522]

@outsideris I guess, the name of fields?

[Charleslee522]

@anarcher If we use Checkpoint struct, we don't have to parse checkpoint string every time.

[sconeman]

It would be better to name them Source andTarget. Later, when we develop TC, we can implement other functions besides boscoin transactions.

[anarcher]

I confused that ‘Source’ as SourceCheckpoint :-)

My approach is same as yours :-) haha

[anarcher]

type Checkpoint struct {
    Hash string // Compound value: "<Subtracted>-<Added>"
    Subtracted string
    Added string
}

[spikeekips]

Resolved by #140