Add configurable Base to int, uint and uint64 flags

[ccremer]

What type of PR is this?

• feature

What this PR does / why we need it:

This allows users to configure the base for integer parsing.

Which issue(s) this PR fixes:

Fixes #1462

Special notes for your reviewer:

• I didn't find the location where I could add godoc for the Base field and its meaning.
  Is this not possible?
• I didn't yet add the same functionality for the IntSlice and UInt64Slice flags. I couldn't find a suitable test case where such a test fits. Do you think it's worth having the base configurable for the slice flags as well? If yes, which test case should I update?
• There seem to be several lookup functions, e.g.

  cli/flag_int.go

  Lines 83 to 93 in 77a5fef

  	func lookupInt(name string, set *flag.FlagSet) int {
  	f := set.Lookup(name)
  	if f != nil {
  	parsed, err := strconv.ParseInt(f.Value.String(), 0, 64)
  	if err != nil {
  	return 0
  	}
  	return int(parsed)
  	}
  	return 0
  	}

  
  I don't have access to the base field in there resp. the flagset. Is this going to be a problem?

Testing

make test

Release Notes

(REQUIRED)

Allow to configure the base for integer parsing in int, uint and uint64 flags

[dearchap]

LGTM. do you think we need to specify somewhere in flag help that the base is X ?

[ccremer]

LGTM. do you think we need to specify somewhere in flag help that the base is X ?

A bit of godoc would certainly help the developers that are setting up the flags, otherwise they'd have to read the source code to understand its meaning and the accepted values. Might also be enough to mention it in the docs, like the timestamp flag (https://cli.urfave.org/v2/#timestamp-flag). Maybe the flag-spec yaml could receive an additional godoc property to render it in https://github.com/urfave/cli/blob/main/cmd/urfave-cli-genflags/generated.gotmpl#L26 ?

Whether the base should also be mentioned in --help (if that was your question) I don't have strong opinions there.