Command line parser for Qt4

Question

I am looking for a command line parser for Qt4.

I did a small google search, and found this: http://www.froglogic.com/pg?id=PublicationsFreeware&category=getopt however it lacks support for "--enable-foo" and "--disable-foo" switches. Besides that, it looks like a real winner.

EDIT:

It seems Frologic removed this. So the best options I see are using Boost (which is not API nor ABI stable) or forking the support for kdelibs. Yay...

Answer 1

QCoreApplication's constructors require (int &argc, char **argv) (and QApplication inherits from QCoreApplication). As the documentation states, it is highly recommended that

Since QApplication also deals with common command line arguments, it is usually a good idea to create it before any interpretation or modification of argv is done in the application itself.

And if you're letting Qt get the first pass at handling arguments anyways, it would also be a good idea to use QStringList QCoreApplication::arguments() instead of walking through argv; QApplication may remove some of the arguments that it has taken for its own use.

This doesn't lend itself to being very compatible with other argument-parsing libraries...

However, kdelibs does come with a nice argument parser, KCmdLineArgs. It is LGPL and can be used without KApplication if you really want (call KCmdLineArgs::init).

KCmdLineOptions options;
options.add("enable-foo", ki18n("enables foo"));
options.add("nodisable-foo", ki18n("disables foo"));
// double negatives are confusing, but this makes disable-foo enabled by default

KCmdLineArgs::addCmdLineOptions(options);
KApplication app;
KCmdLineArgs *args = KCmdLineArgs::parsedArgs();

if (args->isSet("enable-foo") && !args->isSet("disable-foo"))
    cout << "foo enabled" << endl;
else
    cout << "foo disabled" << endl;

Untested (who ever tests what they post on S.O.?).

Answer 2

Since Qt 5.2 you can finally find a solution in QtCore itself: I contributed QCommandLineParser there.

Answer 3

This is more or less the same answer as ephemient, but with a simple regexp to help parse the args. (This way could be useful if you only need a handful of args)

Run with this:

./QArgTest --pid=45 --enable-foo

And the code:

int main(int argc, char *argv[]) {
    QApplication app(argc, argv, false);
    qDebug() << "QApp arg test app"; 

    QStringList args = app.arguments();

    int pid = 0;

    QRegExp rxArgPid("--pid=([0-9]{1,})");
    QRegExp rxArgFooEna("--enable-foo");
    QRegExp rxArgFooDis("--disable-foo");

    for (int i = 1; i < args.size(); ++i) {
        if (rxArgPid.indexIn(args.at(i)) != -1 ) {   
            pid =  rxArgPid.cap(1).toInt();
            qDebug() << i << ":" << args.at(i) << rxArgPid.cap(1) << pid;
        }
        else if (rxArgFooEna.indexIn(args.at(i)) != -1 ) {   
            qDebug() << i << ":" << args.at(i) << "Enable Foo";
        } 
        else if (rxArgFooDis.indexIn(args.at(i)) != -1 ) {   
            qDebug() << i << ":" << args.at(i) << "Disable Foo";
        } 
        else {
            qDebug() << "Uknown arg:" << args.at(i);
        }
    }
    return 0;
}

Answer 4

There is also QxtCommandOptions from http://www.libqxt.org/

Answer 5

That package does support --disable-foo and --enable-foo via opts.addSwitch("disable-foo", &foo_disabled); and opts.addSwitch("enable-foo", &foo_enabled);. You need handle checking both, and dealing with someone specifying both (oops).

What I don't understand is how this has anything to do with QT4...

Answer 6

Look at this: http://code.google.com/p/qtargparser/

Answer 7

It's 2013 and still no "1st party" arg parser. Anyways..if anyone finds themselves facing the same problem and would like to avoid the learning curves that come with cmd parser libs, here is a "quick & dirty" fix for you:-

QString QArgByKey(QString key, QChar sep = QChar('\0') ) //prototype usually in separate header

QString QArgByKey(QString key, QChar sep )
{
    bool sepd=sep!=QChar('\0');
    int pos=sepd?qApp->arguments().indexOf(QRegExp('^'+key+sep+"\\S*")):qApp->arguments().indexOf(QRegExp(key));
    return pos==-1?QString::null:
    (sepd?qApp->arguments().at(pos).split(sep).at(1):(++pos<qApp->arguments().size()?qApp->arguments().at(pos):QString::null));
}

Example:-

user@box:~$ ./myApp  firstKey=Value1 --secondKey Value2 thirdKey=val3.1,val3.2,val3.3 --enable-foo

Usage:

QString param1   = QArgByKey("firstkey",'='); // Returns `Value1` from first pair
QString param2   = QArgByKey("--secondkey"); // Returns `Value2` from second pair
QString param3-1 = QArgByKey("thirdkey",'=').split(',').at(0); // Returns `val3.1`
bool fooEnabled  = qApp->arguments().contains("--enable-foo"); //To check for `--enable-foo` 

Params can be passed in any order

Edit: Updates to this snippet will be found here

Answer 8

A really simple method is to scan "key=value" args,
put them in a table say zz.map: QString -> QVariant,
and get their values with zz.map.value( key, default ). An example:

#include "ztest.h"
Ztest zz;  
int main( int argc, char* argv[] )
{
    zz.eqargs( ++ argv );  // scan  test=2 x=str ... to zz.map

    QString xx = zz.map.value( "xx", "" );
    if( Zint( Size, 10 ))  // a #def -> zz.map.value( "Size", 10 )
        ...

ztest.h is < 1 page, below; same for Python ~ 10 lines.

(Everybody has his/her favorite options parser; this one's about the simplest.
Worth repeating: however you specify options, echo them to output files --
"every scientist I know has trouble keeping track of what parameters they used last time they ran a script".)

To make QPoints etc work one of course needs a QString -> QPoint parser. Anyone know offhand why this doesn't work (in Qt 4.4.3) ?

QPoint pt(0,0);
QDataStream s( "QPoint(1,2)" );
s >> pt;
qDebug() << "pt:" << pt;  // QPoint(1364225897,1853106225) ??

Added 25nov --

// ztest.h: scan args x=2 s=str ... to a key -> string table
// usage:
// Ztest ztest;
// int main( int argc, char* argv[] )
// {
//     QApplication app( argc, argv );
//     ztest.eqargs( ++ argv );  // scan leading args name=value ...
//     int x = Zint( x, 10 );  // arg x= or default 10
//     qreal ff = Zreal( ff, 3.14 );
//     QString s = Zstr( s, "default" );
// care: int misspelled = Zint( misspellled ) -- you lose
//version: 2009-06-09 jun denis

#ifndef ztest_h
#define ztest_h

#include <QHash>
#include <QString>
#include <QVariant>
#include <QRegExp>

//------------------------------------------------------------------------------
class Ztest {
public:
  QHash< QString, QVariant > map;
  int test;  // arg test=num,  if( ztest.test )

  Ztest() : test( 0 ) {}

  QVariant val( const QString& key, const QVariant& default_ = 0 )
  {
    return map.value( key, default_ );
  }

  void setval( const QString& key, const QVariant& val )
  {
    map[key] = val;
    if( key == "test"  ||  key == "Test" )
        test = val.toInt();
  }

//------------------------------------------------------------------------------
    // ztest.eqargs( ++ argv )  scans test=2 x=3 ... -> ztest table
  void eqargs( char** argv )
  {
    char** argv0 = argv;
    char *arg;
    QRegExp re( "(\\w+)=(.*)" );  // name= anything, but not ./file=name
    for( ; (arg = *argv) && re.exactMatch( arg );  argv ++ ){
        setval( re.cap(1), re.cap(2) );
    }
        // change argv[0..] -> args after all name=values
    while(( *argv0++ = *argv++) != 0 ) {}
  }
};

extern Ztest ztest;

    // macros: int x = Zint( x, 10 ): x= arg or default 10
#define Zstr( key, default )    ztest.val( #key, default ).toString()
#define Zint( key, default )    ztest.val( #key, default ).toInt()
#define Zreal( key, default )   ztest.val( #key, default ).toDouble()

#endif

Answer 9

Does it have to be Qt4 specific? If not, GNU Getopt is really nice, although licensing may be a problem if you are not doing open source software.

Answer 10

Also for some fancy options parsing you can try gperf.

IBM has a nice tutorial on it.

Answer 11

Another option I ran across while looking to do this, too:

http://code.google.com/p/qgetopts/

I haven't used it though.