Fix retrieval of pflag stringSlice

[moorereason]

With some extra trace log formatting changes thrown into the mix.

Fixes #112

[CLAassistant]

All committers have signed the CLA.

[awfm9]

Don't see any issues with this, thank you for your contribution.

[aarondl]

@awishformore @moorereason

This PR seems to fix #200 (haven't tested)

But note that I changed two hunks in my workaround, one in find() as in this PR (pretty much the same code) and one in Get() . I wonder if the second one in Get() is necessary. Can anyone who knows the code base advise on this? The code I put in that case is probably wrong, but the fact that there's a similar type check going on there makes me suspicious. I just want to make sure we covered all the possibilities.

If it's truly done, then we should probably close #200 as well.

[awfm9]

I'll try to take a look soon.

[shenwei356]

fix bug of string_slice with square brackets

[shenwei356]

This wrongly trims the "[" and "]" in the flags.

Fix it by:

s := flag.ValueString()
return s[1:len(s)-1]

[shenwei356]

see spf13/pflag#98

[moorereason]

@shenwei356, your solution is probably faster, but strings.TrimPrefix only removes a single "[" character. The problem with pflag was that it used strings.Trim which would remove multiples.

[shenwei356]

you are right!