is there an easiest/shorter way to drop the `g` in...

# announcements

[elect]

is there an easiest/shorter way to drop the g in a string such as v0.1.9-1-g3a259e0 (which is always "$version-g$commitId") other than using something relying on lastIndexOf(-g) and then combining the two substrings?

[rnett]

replace("-g", "-") , and you can use regex instead of a literal if you have a more complex pattern

[elect]

ah, so easy, thanks Ryan

[nkiesel]

be careful: git allows tag names like "a-g", and there the replace("-g", "-") will not work correctly. Using `replace(Regex("-g([a-z0-9]+)$"), "-$1")`is a safer approach (assuming you are really dealing with git describe output where the commit id is always a lowercase hex value)

[elect]

I think the dash is what is exclusive there, commit ids do not contain that

[nkiesel]

commit ids cannot contain dashes, but a tag name can contain dashes. and replace replaces all and not just the last occurrence. Therefore, a tag name "a1-good" combined with commit id "abc123" will be combined to "a-good-gabc123" and "a-good-gabc123".replace("-g", "-") will result in "a-ood-abc123" instead of the intended "a-good-abc123".

[elect]

yeah, replacing the last occurrence would be safer in that case

[elect]

what does the last $ mean here Regex("-g([a-z0-9]+)$") ?

[nkiesel]

$ matches "end of input". This guarantees that the part before it really is the commit id. Without the "$", you would get wrong results for a tag like "a-gdef" because `"a-gdef-gabc123".replace(Regex("-g([a-z0-9]+)"), "-$1")`will return "a-def-abc123" instead of the intended "a-gdef-abc123" because the regex matches twice and "replace" replaces all matching occurances

[nkiesel]

Perhaps there should be a `String.replaceLast`stdlib method, similar to String.replaceFirst. With

fun String.replaceLast(oldValue: String, newValue: String, ignoreCase: Boolean = false): String {
    val index = lastIndexOf(oldValue, ignoreCase = ignoreCase)
    return if (index < 0) this else this.replaceRange(index, index + oldValue.length, newValue)
}

you could just use "a-gdef-gabc123".replaceLast("-g", "-")

[elect]

Regex is a beast I can never stop learning..

[elect]

thanks Norbert