flag: cannot suppress output to os.Stderr

[rogpeppe]

Even with ContinueOnError, some messages are always printed to os.Stderr. This means
that it's not possible to collect the error messages when flag is used to parse options
from the other side of a network connection, for example; neither is it possible to
suppress all output to run a script quietly.

One backwardly compatible solution would be to add an output io.Writer
inside FlagSet and use os.Stderr if that's nil.

As a nice side effect, this could remove the spurious print when flag is tested.

354b17404643 weekly/weekly.2012-01-15

[robpike]

Comment 1:

Labels changed: added priority-go1, removed priority-triage.

Owner changed to builder@golang.org.

[rsc]

Comment 2:

Status changed to Accepted.

[bradfitz]

Comment 3:

http://golang.org/cl/5564065

Owner changed to @bradfitz.

Status changed to Started.

[bradfitz]

Comment 4:

This issue was closed by revision b79ba6a.

Status changed to Fixed.

[gopherbot]

Comment 5 by victorvieux:

What about here: https://code.google.com/p/go/source/browse/src/pkg/flag/flag.go#405 ?

[davecheney]

Comment 6:

This issue was marked closed 18 months ago, please open a new issue.

Labels changed: added restrict-addissuecomment-commit.