The documentation is lacking examples

[zimmski]

go-diff is currently lacking examples for each exported function and method. This would not only help other users but make the whole project a lot better and complete.

[tirithen]

Agreed, I'm rtying to create a gnu patch string and then beeing able to apply it at a later stage but I can't seem to understand how to do this:

var diff = diffmatchpatch.New()

// ApplyPatch takes a GNU patch string and applys it to a string
func ApplyPatch(patch string, text string) string {
    patches, err := diff.PatchFromText(patch)
    if err != nil {
        log.Fatal(err)
        return
    }
    return diff.PatchApply(patches, text)
}

// CreatePatch compares two strings and creates a patch string
func CreatePatch(textA string, textB string) string {
    diff := diff.DiffMain(textA, textB, true)
    // TODO: somehow convert diff to patch string
} 

[zimmski]

@tirithen: Maybe we should open a new issue for your question, but do you mean PatchMake?

[tirithen]

I wanted a way to create a diff/patch string and then I wanted to be able to apply that string. I could not understand how to do this full cycle of diffing and patching

[zimmski]

You can for example do that like this:

diffs := dmp.DiffMain(text1, text2, true)
patches := dmp.PatchMake(text1, diffs)
patchText := dmp.PatchToText(patches)
patchesFromText, _ := dmp.PatchFromText(patchText)
text2FromPatches, _ := dmp.PatchApply(patchesFromText, text1)

[tirithen]

Super! That seem to be it! ;D Got a bit lost in all the methods.

[zimmski]

Yeah, I will partly fix this with #53. Would you be interested in helping me out with the examples? I only have so much time to work on OSS so I would highly appreciate some help.

[idc77]

Complicated.

Imagine a wiki.

Data types

History data type

type History struct {
ID string
EntryID string
Date time.Time
PatchText string
PreviousHistoryID string
}

Entry data type

type Entry struct {
ID string
Content string
}

When I have newText, oldText

New Entry:

• insert new Entry
• diff not needed

Update Entry:

• diff needed

	dmp := diffmatchpatch.New()
	diffs := dmp.DiffMain(new, old, true)
	patches := dmp.PatchMake(new, diffs)
	patchText := dmp.PatchToText(patches)

• get current History ID
• insert new History
• update PreviousHistoryID

Revert to History point

• get histories up to point
• apply all patches in sequencial order
• set Entry content to result

for each of the History entries

	dmp := diffmatchpatch.New()
	patchesFromText, _ := dmp.PatchFromText(patchText)
	text2FromPatches, _ := dmp.PatchApply(patchesFromText, new)

How does Mediawiki do it?

I think I'll just store the old version in the history database without any diffing, only use diff to display differences between revisions. Storage space is not a big issue, but complexity is.

• no difftext stored in database
• no complex operations necessary

Sometimes you need "a rubberducky" to talk to, maybe others will have the same problem and read it.