apf::parameter_map Struct Reference

A "dictionary" for parameters. More...

#include <apf/parameter_map.h>

Inherits std::map< K, T >.

Inherited by apf::MimoProcessor ::Xput< Derived, interface_policy, query_policy >::Params.

Public Member Functions
template<typename... Args>
	parameter_map (Args &&... args)
	Constructor. More...
const std::string &	operator[] (const std::string &k) const
	"Getter". More...
std::string &	operator[] (const std::string &k)
	"Setter". More...
template<typename T >
T	get (const std::string &k, const T &def) const
	Get value converted to given type. More...
template<typename char_T >
std::basic_string< char_T >	get (const std::string &k, const char_T *const def) const
	Overloaded function for character array (aka C-string). More...
template<typename T >
T	get (const std::string &k) const
	Throwing getter. More...
template<typename T >
const std::string &	set (const std::string &k, const T &v)
	Set value. More...
bool	has_key (const std::string &k) const
	Check if a given parameter is available. More...

Detailed Description

A "dictionary" for parameters.

All values are saved as std::string's.

Usage examples:

apf::parameter_map params;
params.set("one", "first value");
params.set("two", 2);
params.set("three", 3.1415);
std::string val1, val5;
int val2, val3, val4;
val1 = params["one"];
val2 = params.get<int>("two");
val3 = params.get<int>("one");  // throws std::invalid_argument exception!
val4 = params.get("one", 42);  // default value 42 if conversion fails
                               // template argument is deduced from 2nd arg
if (params.has_key("four"))
{
  // this is not done because there is no key named "four":
  do_something();
}
params["four"] = "42";  // throws std::out_of_range exception!
val5 = params["four"];  // throws std::out_of_range exception!

Examples

audiofile_simpleprocessor.cpp, dummy_example.cpp, jack_simpleprocessor.cpp, mex_simpleprocessor.cpp, and simpleprocessor.h.

Definition at line 67 of file parameter_map.h.

Constructor & Destructor Documentation

parameter_map()

template<typename... Args>

apf::parameter_map::parameter_map ( Args &&...  args )

inlineexplicit

Constructor.

All parameters are forwarded to the std::map constructor.

Definition at line 73 of file parameter_map.h.

Member Function Documentation

operator[]() [1/2]

const std::string & apf::parameter_map::operator[] ( const std::string &  k ) const

inline

"Getter".

Parameters

k	Name of the parameter which should be retrieved.

Returns

const reference to the value referenced by k.

Exceptions

std::out_of_range

if the key k doesn't exist. You should've checked beforehand with has_key() ...

See also

has_key(), get()

Definition at line 84 of file parameter_map.h.

operator[]() [2/2]

std::string & apf::parameter_map::operator[] ( const std::string &  k )

inline

"Setter".

Well, not really. It just gives you a reference where you can assign stuff to.

Parameters

k	Name of the parameter which should be set. The parameter has to be in the map already, if not, an exception is thrown! If you want to add a new value, use set().

Returns

non-const reference to the value referenced by k. You can assign a std::string to actually set a new value.

Exceptions

std::out_of_range

if the key k doesn't exist yet.

See also

has_key(), set()

Definition at line 106 of file parameter_map.h.

get() [1/3]

template<typename T >

T apf::parameter_map::get ( const std::string &  k, const T &  def  ) const

inline

Get value converted to given type.

Template Parameters

T	The desired type. Can be omitted if def is specified.

Parameters

k	Name of the parameter which should be retrieved.
def	Default value for cases where conversion fails.

Returns

Value referenced by k, converted to type T. If the key k isn't available, or if the conversion failed, def is returned.

Warning

If the result is equal to the default value def, there is no way to know ...

• if the key was available
• if the conversion was successful

To check the former, you can use has_key(), for the latter you have to get the value as string (with operator[]()) and convert it yourself (e.g. with apf::str::S2A()). Or you can use the throwing version of get<T>().

Examples

simpleprocessor.h.

Definition at line 135 of file parameter_map.h.

Referenced by get().

get() [2/3]

template<typename char_T >

std::basic_string< char_T > apf::parameter_map::get ( const std::string &  k, const char_T *const  def  ) const

inline

Overloaded function for character array (aka C-string).

This is mainly used to specify a string literal as default value, which wouldn't work with the other get() version, e.g.

apf::parameter_map params;
params.set("id", "item42");
std::string id1, id2, name1, name2;
id1   = params.get("id"  , "no_id_available"); // id1   = "item42";
id2   = params.get("id"  , "item42");          // id2   = "item42";
name1 = params.get("name", "Default Name");    // name1 = "Default Name";
name2 = params.get("name", "");                // name2 = "";

Template Parameters

T	The given character type. Can be omitted if def is specified (which is normally the case!).

Parameters

k	Name of the parameter which should be retrieved.
def	Default value for cases where conversion fails.

Returns

Value referenced by k, converted to a std::basic_string<char_T>. If the key k isn't available, or if the conversion failed, def is returned.

Warning

Same warning as for the other get() version with default value.

Definition at line 174 of file parameter_map.h.

References get().

get() [3/3]

template<typename T >

T apf::parameter_map::get ( const std::string &  k ) const

inline

Throwing getter.

Template Parameters

T	Desired output type

Parameters

k	Name of the parameter which should be retrieved.

Exceptions

std::out_of_range	if the key k is not available
std::invalid_argument	if the content cannot be converted to T

Definition at line 186 of file parameter_map.h.

set()

template<typename T >

const std::string & apf::parameter_map::set ( const std::string &  k, const T &  v  )

inline

Set value.

Template Parameters

T	Input type

Parameters

k	Name of parameter to be set
v	Value. Will be converted to std::string.

Returns

const reference to the std::string representation of v. If "" is returned, the conversion failed (or v was "" originally).

Examples

audiofile_simpleprocessor.cpp, and jack_simpleprocessor.cpp.

Definition at line 209 of file parameter_map.h.

References apf::str::A2S().

has_key()

bool apf::parameter_map::has_key ( const std::string &  k ) const

inline

Check if a given parameter is available.

Parameters

k	The parameter name

Returns

true if k is available

Definition at line 218 of file parameter_map.h.

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The documentation for this struct was generated from the following file:

• apf/parameter_map.h