> On May 24, 2021, at 9:36 PM, Nick Rosbrook <rosbro...@gmail.com> wrote:
>
> Add a ContextOption type to support functional options in NewContext.
> Then, add a variadic ContextOption parameter to NewContext, which allows
> callers to specify 0 or more configuration options.
>
> For now, just add the WithLogLevel option so that callers can set the
> log level of the Context's xentoollog_logger. Future configuration
> options can be created by adding an appropriate field to the
> contextOptions struct and creating a With<OptionName> function to return
> a ContextOption
>
> Signed-off-by: Nick Rosbrook <rosbro...@ainfosec.com>
> ---
> tools/golang/xenlight/xenlight.go | 44 +++++++++++++++++++++++++++++--
> 1 file changed, 42 insertions(+), 2 deletions(-)
>
> diff --git a/tools/golang/xenlight/xenlight.go
> b/tools/golang/xenlight/xenlight.go
> index f68d7b6e97..65f93abe32 100644
> --- a/tools/golang/xenlight/xenlight.go
> +++ b/tools/golang/xenlight/xenlight.go
> @@ -136,7 +136,7 @@ func sigchldHandler(ctx *Context) {
> }
>
> // NewContext returns a new Context.
> -func NewContext() (ctx *Context, err error) {
> +func NewContext(opts ...ContextOption) (ctx *Context, err error) {
> ctx = &Context{}
>
> defer func() {
> @@ -146,8 +146,19 @@ func NewContext() (ctx *Context, err error) {
> }
> }()
>
> + // Set the default context options. These fields may
> + // be modified by the provided opts.
> + copts := &contextOptions{
> + logLevel: LogLevelError,
> + }
> +
> + for _, opt := range opts {
> + opt.apply(copts)
> + }
> +
> // Create a logger
> - ctx.logger = C.xtl_createlogger_stdiostream(C.stderr, C.XTL_ERROR, 0)
> + ctx.logger = C.xtl_createlogger_stdiostream(C.stderr,
> + C.xentoollog_level(copts.logLevel), 0)
>
> // Allocate a context
> ret := C.libxl_ctx_alloc(&ctx.ctx, C.LIBXL_VERSION, 0,
> @@ -201,6 +212,35 @@ func (ctx *Context) Close() error {
> return nil
> }
>
> +type contextOptions struct {
> + logLevel LogLevel
> +}
> +
> +// ContextOption is used to configure options for a Context.
> +type ContextOption interface {
> + apply(*contextOptions)
> +}
> +
> +type funcContextOption struct {
> + f func(*contextOptions)
> +}
> +
> +func (fco *funcContextOption) apply(c *contextOptions) {
> + fco.f(c)
> +}
Why all this convolution with interfaces and such, rather than just defining
ContextOption as a function pointer? Is it just to keep contextOptions out of
the documentation page?
-George
