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https://issues.apache.org/jira/browse/MESOS-2711?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Marco Massenzio updated MESOS-2711:
-----------------------------------
Description:
When using {{stout/flags/flags.hpp}} and implementing our own {{Flags}} class
(derived from {{flags::FlagsBase}}) pretty much everyone ends up
re-implementing some variant of the following:
{code}
void usage(const char* argv0, const flags::FlagsBase& flags)
{
cerr << "Usage: " << os::basename(argv0).get() << " [...]" << endl
<< endl
<< "Supported options:" << endl
<< flags.usage();
}
{code}
and in {{main.cpp}}:
{code}
int main(int argc, char** argv)
{
bool help;
flags.add(&help,
"help",
"Prints this help message",
false);
// ...
if (load.isError()) {
cerr << load.error() << endl;
usage(argv[0], flags);
exit(1);
}
if (help) {
usage(argv[0], flags);
exit(1);
}
}
{code}
Note that {{FlagsBase}} already "knows" {{argv[0]}} and it would be nice if it
implemented the "help" functionality itself, so that everyone immediately gains
access to it; further, the {{printUsage()}} method could be implemented easily
by simply adding the facility for derived classes to specify some form of a
"blurb" (the bit that is emitted between the {{Usage:}} line and the
{{Options:}} body and, possibly, to customize the "usage" one-liner.
was:
When using {{stout/flags/flags.hpp}} and implementing our own {{Flags}} class
(derived from {{flags::FlagsBase}}) pretty much everyone ends up
re-implementing some variant of the following:
{code}
void printUsage(const string& prog, const string& options)
{
cout << "Usage: " << os::basename(prog).get() << " [options]\n\n"
"One (and only one) of the following options MUST be present.\n\n"
"Options:\n" << options << endl;
}
{code}
and in {{main.cpp}}:
{code}
int main(int argc, char** argv)
{
MyFlags flags;
bool help;
flags.add(&help, "help", "Prints this help message", false);
Try<Nothing> load = flags.load(None(), argc, argv);
// ...
if (help) {
printUsage(argv[0], flags.usage());
}
// ...
}
{code}
Note that {{FlagsBase}} already "knows" {{argv[0]}} and it would be nice if it
implemented the "help" functionality itself, so that everyone immediately gains
access to it; further, the {{printUsage()}} method could be implemented easily
by simply adding the facility for derived classes to specify some form of a
"blurb" (the bit that is emitted between the {{Usage:}} line and the
{{Options:}} body and, possibly, to customize the "usage" one-liner.
> Add some commonly-used utility to stout/flags
> ---------------------------------------------
>
> Key: MESOS-2711
> URL: https://issues.apache.org/jira/browse/MESOS-2711
> Project: Mesos
> Issue Type: Improvement
> Components: stout
> Affects Versions: 0.22.0
> Reporter: Marco Massenzio
> Assignee: Marco Massenzio
> Priority: Minor
>
> When using {{stout/flags/flags.hpp}} and implementing our own {{Flags}} class
> (derived from {{flags::FlagsBase}}) pretty much everyone ends up
> re-implementing some variant of the following:
> {code}
> void usage(const char* argv0, const flags::FlagsBase& flags)
> {
> cerr << "Usage: " << os::basename(argv0).get() << " [...]" << endl
> << endl
> << "Supported options:" << endl
> << flags.usage();
> }
> {code}
> and in {{main.cpp}}:
> {code}
> int main(int argc, char** argv)
> {
> bool help;
> flags.add(&help,
> "help",
> "Prints this help message",
> false);
> // ...
> if (load.isError()) {
> cerr << load.error() << endl;
> usage(argv[0], flags);
> exit(1);
> }
> if (help) {
> usage(argv[0], flags);
> exit(1);
> }
> }
> {code}
> Note that {{FlagsBase}} already "knows" {{argv[0]}} and it would be nice if
> it implemented the "help" functionality itself, so that everyone immediately
> gains access to it; further, the {{printUsage()}} method could be implemented
> easily by simply adding the facility for derived classes to specify some form
> of a "blurb" (the bit that is emitted between the {{Usage:}} line and the
> {{Options:}} body and, possibly, to customize the "usage" one-liner.
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