xtd::diagnostics::default_trace_listener Class Reference

Inheritance diagram for xtd::diagnostics::default_trace_listener:

Definition

Provides the default output methods and behavior for tracing.

class core_export_ default_trace_listener : public xtd::diagnostics::trace_listener

Inheritance

xtd::object → xtd::abstract_object → xtd::diagnostics::trace_listener → xtd::diagnostics::default_trace_listener

Header

#include <xtd/diagnostics/default_trace_listener> 

Namespace

xtd::diagnostics

Library

xtd.core

Examples

The following code example calculates binomial coefficients, which are values used in probability and statistics. This example uses a xtd::diagnostics::default_trace_listener to trace results and log errors. It creates a new xtd::diagnostics::default_trace_listener, adds it to the xtd::diagnostics::trace::listeners collection, and sets the xtd::diagnostics::default_trace_listener::log_file_name property to the log file specified in the command-line arguments.

If an error is detected while processing the input parameter, or if the calc_binomial function throws an exception, the xtd::diagnostics::default_trace_listener::fail method logs and displays an error message. If the xtd::diagnostics::default_trace_listener::assert_ui_enabled property is false, the error message is also written to the console. When the result is calculated successfully, the xtd::diagnostics::default_trace_listener::write and xtd::diagnostics::default_trace_listener::write_line methods write the results to the log file.

The xtd::diagnostics::default_trace_listener::fail, xtd::diagnostics::default_trace_listener::write, and xtd::diagnostics::default_trace_listener::write_line methods cause trace information to be written only to the xtd::diagnostics::default_trace_listener. To write trace information to all listeners in the xtd::diagnostics::trace::listeners collection, use the xtd::diagnostics::trace::fail, xtd::diagnostics::trace::write, and xtd::diagnostics::trace::write_line methods of the xtd::diagnostics::trace class.

#include <xtd/diagnostics/trace>
#include <xtd/diagnostics/default_trace_listener>
#include <xtd/console>
#include <xtd/startup>
 
using namespace std;
using namespace xtd;
using namespace xtd::diagnostics;
 
class binomial {
public:
  // args(0) is the number of possibilities for binomial coefficients.
  // args(1) is the file specification for the trace log file.
  static auto main(const vector<ustring>& args) {
    auto possibilities = .0l;
    auto iter = .0l;
    
    // Remove the original default trace listener.
    trace::listeners().erase(trace::listeners().begin());
    
    // Create and add a new default trace listener.
    auto default_listener = make_shared<default_trace_listener>();
    trace::listeners().push_back(default_listener);
    
    // Assign the log file specification from the command line, if entered.
    if (args.size() >= 2)
      default_listener->log_file_name(args[1]);
      
    // Validate the number of possibilities argument.
    if (args.size() >= 1) {
      // Verify that the argument is a number within the correct range.
      try {
        const auto MAX_POSSIBILITIES = 99.0l;
        possibilities = parse<decimal>(args[0]);
        if (possibilities < 0 || possibilities > MAX_POSSIBILITIES)
          throw new system_exception(ustring::format("The number of possibilities must be in the range 0..{}.", MAX_POSSIBILITIES));
      } catch (const system_exception& ex) {
        auto fail_message = ustring::format("\"{}\" is not a valid number of possibilities.", args[0]);
        default_listener->fail(fail_message, ex.message());
        if (!default_listener->assert_ui_enabled())
          console::write_line(fail_message + "\n" + ex.message());
        return;
      }
    } else {
      // Report that the required argument is not present.
      const auto ENTER_PARAM = "Enter the number of possibilities as a command line argument.";
      default_listener->fail(ENTER_PARAM);
      if (!default_listener->assert_ui_enabled())
        console::write_line(ENTER_PARAM);
      return;
    }
    
    for (iter = 0; iter <= possibilities; iter++) {
      auto result = .0l;
      auto binomial = ustring::empty_string;
      
      // Compute the next binomial coefficient and handle all exceptions.
      try {
        result = calc_binomial(possibilities, iter);
      } catch (const system_exception& ex) {
        auto fail_message = ustring::format("An exception was raised when calculating Binomial( {}, {} ).", possibilities, iter);
        default_listener->fail(fail_message, ex.message());
        if (!default_listener->assert_ui_enabled())
          console::write_line(fail_message + "\n" + ex.message());
        return;
      }
      
      // Format the trace and console output.
      binomial = ustring::format("Binomial( {0}, {1} ) = ", possibilities, iter);
      default_listener->write(binomial);
      default_listener->write_line(ustring::format("{}", result));
      console::write_line("{0} {1}", binomial, result);
    }
  }
  
  static decimal calc_binomial(xtd::decimal possibilities, decimal outcomes) {
    // Calculate a binomial coefficient, and minimize the chance of overflow.
    auto result = 1.0l;
    auto iter = .0l;
    for (iter = 1.0l; iter <= possibilities - outcomes; iter++) {
      result *= outcomes + iter;
      result /= iter;
    }
    return result;
  }
};
 
startup_(binomial::main);
 
// This code can produces the following output :
//
// Binomial( 20, 0 ) = 1
// Binomial( 20, 1 ) = 20
// Binomial( 20, 2 ) = 190
// Binomial( 20, 3 ) = 1140
// Binomial( 20, 4 ) = 4845
// Binomial( 20, 5 ) = 15504
// Binomial( 20, 6 ) = 38760
// Binomial( 20, 7 ) = 77520
// Binomial( 20, 8 ) = 125970
// Binomial( 20, 9 ) = 167960
// Binomial( 20, 10 ) = 184756
// Binomial( 20, 11 ) = 167960
// Binomial( 20, 12 ) = 125970
// Binomial( 20, 13 ) = 77520
// Binomial( 20, 14 ) = 38760
// Binomial( 20, 15 ) = 15504
// Binomial( 20, 16 ) = 4845
// Binomial( 20, 17 ) = 1140
// Binomial( 20, 18 ) = 190
// Binomial( 20, 19 ) = 20
// Binomial( 20, 20 ) = 1

Public Constructors
	default_trace_listener ()
	Initializes a new instance of the default_trace_listener class with "default" as its xtd::diagnostics::default_trace_listener::name property value.

Public Properties
bool	assert_ui_enabled () const noexcept
	Gets a value indicating whether the application is running in user-interface mode.
void	assert_ui_enabled (bool assert_ui_enabled) noexcept
	Sets a value indicating whether the application is running in user-interface mode.
xtd::ustring	log_file_name () const noexcept
	Gets the name of a log file to write trace or debug messages to.
void	log_file_name (const xtd::ustring log_file_name) noexcept
	Sets the name of a log file to write trace or debug messages to.

Public Methods
void	close () override
	When overridden in a derived class, closes the output stream so it no longer receives tracing or debugging output.
void	flush () override
	When overridden in a derived class, flushes the output buffer.
void	write (const xtd::ustring &message) override
	Writes the message to the listener you create when you implement the trace_listener class.
void	write_line (const xtd::ustring &message) override
	Writes the message to the listener you create when you implement the trace_listener class followed by a line terminator.followed by a line terminator.

Additional Inherited Members
Public Member Functions inherited from xtd::diagnostics::trace_listener
	trace_listener ()=default
	Initializes a new instance of the trace_listener class.
	trace_listener (const xtd::ustring &name)
	Initializes a new instance of the trace_listener class using the specified name as the listener.
uint32	indent_level () const noexcept
	Gets the indent level.
void	indent_level (uint32 indent_level) noexcept
	Sets the indent level.
uint32	indent_size () const noexcept
	Gets the number of spaces in an indent.
void	indent_size (uint32 indent_size) noexcept
	Sets the number of spaces in an indent.
virtual bool	is_thread_safe () const noexcept
	Gets a value indicating whether the trace listener is thread safe.
const xtd::ustring &	name () const noexcept
	Gets or sets a name for this TraceListener.
void	name (const xtd::ustring &name) noexcept
	Sets a name for this TraceListener.
trace_options	trace_output_options () const noexcept
	Gets the trace output options.
void	trace_output_options (trace_options trace_output_options) noexcept
	Sets the trace output options.
virtual void	fail (const xtd::ustring &message)
	Emits an error message to the listener you create when you implement the TraceListener class.
virtual void	fail (const xtd::ustring &message, const xtd::ustring &detail_message)
	Emits the specified error message.
template<typename object >
void	trace_data (const xtd::diagnostics::trace_event_cache &event_cache, const xtd::ustring &source, const xtd::diagnostics::trace_event_type &event_type, int32 id, const object &data)
	Writes trace information, a data object and event information to the listener specific output.
template<typename object >
void	trace_data (const xtd::diagnostics::trace_event_cache &event_cache, const xtd::ustring &source, const xtd::diagnostics::trace_event_type &event_type, int32 id, const std::vector< object > &data)
	Writes trace information, a data object and event information to the listener specific output.
template<typename ... objects>
void	trace_data (const xtd::diagnostics::trace_event_cache &event_cache, const xtd::ustring &source, const xtd::diagnostics::trace_event_type &event_type, int32 id, const objects &... data)
	Writes trace information, an array of data objects and event information to the listener specific output.
virtual void	trace_event (const xtd::diagnostics::trace_event_cache &event_cache, const xtd::ustring &source, const xtd::diagnostics::trace_event_type &event_type, int32 id)
	Writes trace and event information to the listener specific output.
virtual void	trace_event (const xtd::diagnostics::trace_event_cache &event_cache, const xtd::ustring &source, const xtd::diagnostics::trace_event_type &event_type, int32 id, const xtd::ustring &message)
	Writes trace information, a message, and event information to the listener specific output.
template<typename ... objects>
void	trace_event (const xtd::diagnostics::trace_event_cache &event_cache, const xtd::ustring &source, const xtd::diagnostics::trace_event_type &event_type, int32 id, const xtd::ustring &format, const objects &... args)
	Writes trace information, a formatted array of objects and event information to the listener specific output.
template<typename activity_id_type >
void	trace_transfer (const xtd::diagnostics::trace_event_cache &event_cache, const xtd::ustring &source, int32 id, const xtd::ustring &message, const activity_id_type &related_activity_id)
	Writes trace information, a message, a related activity identity and event information to the listener specific output.
template<typename object >
void	write (const object &o)
	Writes the value of the object's ToString method to the listener you create when you implement the TraceListener class.
template<typename object >
void	write (const object &o, const xtd::ustring &category)
	Writes a category name and the value of the object's ToString method to the listener you create when you implement the TraceListener class.
template<typename object >
void	write_line (const object &o)
	Writes the value of the object's ToString method to the listener you create when you implement the TraceListener class.
template<typename object >
void	write_line (const object &o, const xtd::ustring &category)
	Writes a category name and the value of the object's ToString method to the listener you create when you implement the TraceListener class.
Public Member Functions inherited from xtd::object
	object ()=default
	Create a new instance of the ultimate base class object.
bool	equals (const object &obj) const noexcept
	Determines whether the specified object is equal to the current object.
virtual size_t	get_hash_code () const noexcept
	Serves as a hash function for a particular type.
virtual type_object	get_type () const noexcept
	Gets the type of the current instance.
template<typename object_t >
std::unique_ptr< object_t >	memberwise_clone () const noexcept
	Creates a shallow copy of the current object.
virtual xtd::ustring	to_string () const noexcept
	Returns a sxd::ustring that represents the current object.
Static Public Member Functions inherited from xtd::object
static bool	equals (const object &object_a, const object &object_b) noexcept
	Determines whether the specified object instances are considered equal.
static bool	reference_equals (const object &object_a, const object &object_b) noexcept
	Determines whether the specified object instances are the same instance.
Protected Member Functions inherited from xtd::diagnostics::trace_listener
bool	need_indent () const noexcept
	Gets a value indicating whether to indent the output.
void	need_indent (bool need_indent) noexcept
	Sets a value indicating whether to indent the output.
void	thread_safe (bool thread_safe) noexcept
	Sets a value indicating whether the trace listener is thread safe.
virtual void	write_indent ()
	Writes the indent to the listener you create when you implement this class, and resets the NeedIndent property to false.
Protected Member Functions inherited from xtd::abstract_object
	abstract_object ()=default
	Initializes a new instance of the xtd::abstract_object class.

Constructor & Destructor Documentation

default_trace_listener()

xtd::diagnostics::default_trace_listener::default_trace_listener

(

)

Initializes a new instance of the default_trace_listener class with "default" as its xtd::diagnostics::default_trace_listener::name property value.

Examples

The following code example removes the xtd::diagnostics::default_trace_listener provided by the application from the xtd::diagnostics::trace::listeners collection and then creates a new xtd::diagnostics::default_trace_listener and adds it to the xtd::diagnostics::trace::listeners collection.

// Remove the original default trace listener.
trace::listeners().erase(trace::listeners().begin());
 
// Create and add a new default trace listener.
shared_ptr<default_trace_listener> default_listener = make_shared<default_trace_listener>();
trace::listeners().push_back(default_listener);
 
// Assign the log file specification from the command line, if entered.
if (args.size() >= 2)
  default_listener->log_file_name(args[1]);

Member Function Documentation

assert_ui_enabled() [1/2]

bool xtd::diagnostics::default_trace_listener::assert_ui_enabled ( ) const

noexcept

Gets a value indicating whether the application is running in user-interface mode.

Returns

true if user-interface mode is enabled; otherwise, false.

Examples

The following code example calls a function that calls the xtd::diagnostics::default_trace_listener::fail method to log an error message if the function throws an exception. If the xtd::diagnostics::default_trace_listener::assert_ui_enabled property is false, the method also writes the error message to the console.

// Compute the next binomial coefficient and handle all exceptions.
  result = calc_binomial(possibilities, iter);
} catch (const system_exception& ex) {
  ustring fail_message = ustring::format("An exception was raised when calculating Binomial( {}, {} ).", possibilities, iter);
  default_listener->fail(fail_message, ex.message());
  if (!default_listener->assert_ui_enabled())
    console::write_line(fail_message + "\n" + ex.message());
  return;
}

assert_ui_enabled() [2/2]

void xtd::diagnostics::default_trace_listener::assert_ui_enabled ( bool  assert_ui_enabled )

noexcept

Sets a value indicating whether the application is running in user-interface mode.

Parameters

assert_ui_enabled

true if user-interface mode is enabled; otherwise, false.

Examples

The following code example calls a function that calls the xtd::diagnostics::default_trace_listener::fail method to log an error message if the function throws an exception. If the xtd::diagnostics::default_trace_listener::assert_ui_enabled property is false, the method also writes the error message to the console.

// Compute the next binomial coefficient and handle all exceptions.
  result = calc_binomial(possibilities, iter);
} catch (const system_exception& ex) {
  ustring fail_message = ustring::format("An exception was raised when calculating Binomial( {}, {} ).", possibilities, iter);
  default_listener->fail(fail_message, ex.message());
  if (!default_listener->assert_ui_enabled())
    console::write_line(fail_message + "\n" + ex.message());
  return;
}

close()

void xtd::diagnostics::default_trace_listener::close ( )

overridevirtual

When overridden in a derived class, closes the output stream so it no longer receives tracing or debugging output.

Remarks

Use this method when the output is going to a file, such as to the TextWriterTraceListener. After a call to this method, you must reinitialize the object.

Reimplemented from xtd::diagnostics::trace_listener.

flush()

void xtd::diagnostics::default_trace_listener::flush ( )

overridevirtual

When overridden in a derived class, flushes the output buffer.

Reimplemented from xtd::diagnostics::trace_listener.

log_file_name() [1/2]

xtd::ustring xtd::diagnostics::default_trace_listener::log_file_name ( ) const

noexcept

Gets the name of a log file to write trace or debug messages to.

Returns

The name of a log file to write trace or debug messages to.

Examples

The following code example creates a new xtd::diagnostics::default_trace_listener, adds it to the xtd::diagnostics::trace::listeners collection, and sets the xtd::diagnostics::default_trace_listener::log_file_name property to the log file specified in the command-line arguments.

// Create and add a new default trace listener.
shared_ptr<default_trace_listener> default_listener = make_shared<default_trace_listener>();
trace::listeners().push_back(default_listener);
 
// Assign the log file specification from the command line, if entered.
if (args.size() >= 2)
  default_listener->log_file_name(args[1]);

log_file_name() [2/2]

void xtd::diagnostics::default_trace_listener::log_file_name ( const xtd::ustring  log_file_name )

noexcept

Sets the name of a log file to write trace or debug messages to.

Parameters

log_file_name

The name of a log file to write trace or debug messages to.

Examples

The following code example creates a new xtd::diagnostics::default_trace_listener, adds it to the xtd::diagnostics::trace::listeners collection, and sets the xtd::diagnostics::default_trace_listener::log_file_name property to the log file specified in the command-line arguments.

// Create and add a new default trace listener.
shared_ptr<default_trace_listener> default_listener = make_shared<default_trace_listener>();
trace::listeners().push_back(default_listener);
 
// Assign the log file specification from the command line, if entered.
if (args.size() >= 2)
  default_listener->log_file_name(args[1]);

write()

void xtd::diagnostics::default_trace_listener::write ( const xtd::ustring &  message )

overridevirtual

Writes the message to the listener you create when you implement the trace_listener class.

Parameters

message

A string you want to write.

Implements xtd::diagnostics::trace_listener.

write_line()

void xtd::diagnostics::default_trace_listener::write_line ( const xtd::ustring &  message )

overridevirtual

Writes the message to the listener you create when you implement the trace_listener class followed by a line terminator.followed by a line terminator.

Parameters

message

A string you want to write.

Implements xtd::diagnostics::trace_listener.

---

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

• xtd.core/include/xtd/diagnostics/default_trace_listener.h