C++ Boost Program Options 中的向量参数
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Vector arguments in Boost Program Options
提问by Szabolcs
I have two related questions:
我有两个相关的问题：
What is the simplestway to allow passing a series of values, using Boost Program Options? My aim is to avoid
prog --opt 1 --opt 2 --opt 3and haveprog --opt 1 2 3instead.What is the simplest way to have an option that takes exactlytwo numbers, e.g.
prog --opt 137 42?
使用 Boost Program Options 允许传递一系列值的最简单方法是什么？我的目标是避免
prog --opt 1 --opt 2 --opt 3并拥有prog --opt 1 2 3。拥有一个恰好需要两个数字的选项的最简单方法是什么，例如
prog --opt 137 42？
(I don't need any "free" program parameters.)
（我不需要任何“免费”程序参数。）
采纳答案by rcollyer
For the first part, this should work
对于第一部分，这应该有效
namespace po = boost::program_options;
po::option_descriptions desc("");
desc.add_options()
("opt", po::value<std::vector<int> >()->multitoken(), "description");
The second part, requires a bit more work. The function po::valuereturns a po::typed_value< T, charT >on which you'll have to override the behavior of several functions, as follows
第二部分，需要更多的工作。该函数po::value返回一个po::typed_value< T, charT >，您必须在其上覆盖多个函数的行为，如下所示
template< typename T, typename charT = char >
class fixed_tokens_typed_value : public po::typed_value< T, charT > {
unsigned _min, _max;
typedef po::typed_value< T, charT > base;
public:
fixed_tokens_typed_value( T * t, unsigned min, unsigned max )
: _min(min), _max(max), base( t ) {
base::multitoken();
}
virtual multi_typed_value* min_tokens( unsigned min ) {
_min = min;
return *this;
}
unsigned min_tokens() const {return _min;}
virtual multi_typed_value* max_tokens( unsigned max ) {
_max = max;
return *this;
}
unsigned max_tokens() const {return _max;}
base* zero_tokens() {
_min = _max = 0;
base::zero_tokens();
return *this;
}
}
which needs to be accompanied by
这需要伴随
template< typename T >
fixed_tokens_typed_value< T >
fixed_tokens_value(unsigned min, unsigned max) {
return fixed_tokens_typed_value< T >(0, min, max ); }
template< typename T >
fixed_tokens_typed_value< T >
fixed_tokens_value(T * t, unsigned min, unsigned max) {
fixed_tokens_typed_value< T >* r = new
fixed_tokens_typed_value< T >(t, min, max);
return r; }
Then
然后
desc.add_options()
("opt", po::fixed_tokens_value<std::vector<int> >(2,2), "description");
should work. I have not yet had a chance to test it, so it likely contains a few bugs. But, at a minimum, should give you an idea of what you need.
应该管用。我还没有机会测试它，所以它可能包含一些错误。但是，至少应该让您了解您需要什么。
回答by Bee
This is a late answer but I hope it helps someone. You could easily use the same technique in item #1, except you need to add another validation on the number of items in your vector:
这是一个迟到的答案，但我希望它可以帮助某人。您可以轻松地在第 1 项中使用相同的技术，但您需要对向量中的项数添加另一个验证：
from rcollyer's example:
来自 rcollyer 的例子：
namespace po = boost::program_options;
po::option_descriptions desc("");
desc.add_options()
("opt", po::value<std::vector<int> >()->multitoken(), "description");
po::variables_map vm;
po::store(po::parse_command_line(argc, argv, desc), vm);
po::notify(vm);
vector<int> opts;
if (!vm["opt"].empty() && (opts = vm["opt"].as<vector<int> >()).size() == 2) {
// good to go
}
