#include <default_trace_listener.h>

Definition

Provides the default output methods and behavior for tracing.

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

Inheritance: xtd::diagnostics::trace_listener → 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/xtd>
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 void main(const vector<ustring>& args) {
decimal possibilities;
decimal iter;

// 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]);

// Validate the number of possibilities argument.
if (args.size() >= 1) {
// Verify that the argument is a number within the correct range.
try {
const decimal MAX_POSSIBILITIES = 99;
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) {
ustring 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 ustring 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++) {
decimal result;
ustring binomial;

// Compute the next binomial coefficient and handle all exceptions.
try {
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;
}

// 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.
decimal result = 1;
decimal iter;
for (iter = 1; iter <= possibilities - outcomes; iter++) {
result *= outcomes + iter;
result /= iter;
}
return result;
}
};
startup_(binomial);
// 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

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. More...

Properties
bool	assert_ui_enabled ()
	Gets a value indicating whether the application is running in user-interface mode. More...

void	assert_ui_enabled (bool assert_ui_enabled)
	Sets a value indicating whether the application is running in user-interface mode. More...

xtd::ustring	log_file_name () const
	Gets the name of a log file to write trace or debug messages to. More...

void	log_file_name (const xtd::ustring log_file_name)
	Sets the name of a log file to write trace or debug messages to. More...

Methods
void	close () override
	When overridden in a derived class, closes the output stream so it no longer receives tracing or debugging output. More...

void	flush () override
	When overridden in a derived class, flushes the output buffer. More...

void	write (const xtd::ustring &message) override
	Writes the message to the listener you create when you implement the trace_listener class. More...

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. More...

Additional Inherited Members
Public Member Functions inherited from xtd::diagnostics::trace_listener
	trace_listener ()=default
	Initializes a new instance of the trace_listener class. More...

	trace_listener (const xtd::ustring &name)
	Initializes a new instance of the trace_listener class using the specified name as the listener. More...

unsigned int	indent_level () const
	Gets the indent level. More...

void	indent_level (unsigned int indent_level)
	Sets the indent level. More...

unsigned int	indent_size () const
	Gets the number of spaces in an indent. More...

void	indent_size (unsigned int indent_size)
	Sets the number of spaces in an indent. More...

virtual bool	is_thread_safe () const
	Gets a value indicating whether the trace listener is thread safe. More...

const xtd::ustring &	name () const
	Gets or sets a name for this TraceListener. More...

void	name (const xtd::ustring &name)
	Sets a name for this TraceListener. More...

const trace_options &	trace_output_options () const
	Gets the trace output options. More...

void	trace_output_options (const trace_options &trace_output_options)
	Sets the trace output options. More...

virtual void	fail (const xtd::ustring &message)
	Emits an error message to the listener you create when you implement the TraceListener class. More...

virtual void	fail (const xtd::ustring &message, const xtd::ustring &detail_message)
	Emits the specified error message. More...

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, int id, const object &data)
	Writes trace information, a data object and event information to the listener specific output. More...

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, int id, const std::vector< object > &data)
	Writes trace information, a data object and event information to the listener specific output. More...

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, int id, const objects &... data)
	Writes trace information, an array of data objects and event information to the listener specific output. More...

virtual void	trace_event (const xtd::diagnostics::trace_event_cache &event_cache, const xtd::ustring &source, const xtd::diagnostics::trace_event_type &event_type, int id)
	Writes trace and event information to the listener specific output. More...

virtual void	trace_event (const xtd::diagnostics::trace_event_cache &event_cache, const xtd::ustring &source, const xtd::diagnostics::trace_event_type &event_type, int id, const xtd::ustring &message)
	Writes trace information, a message, and event information to the listener specific output. More...

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, int id, const xtd::ustring &format, const objects &... args)
	Writes trace information, a formatted array of objects and event information to the listener specific output. More...

template<typename activity_id_type >
void	trace_transfer (const xtd::diagnostics::trace_event_cache &event_cache, const xtd::ustring &source, int 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. More...

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. More...

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. More...

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. More...

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. More...

Protected Member Functions inherited from xtd::diagnostics::trace_listener
bool	need_indent () const
	Gets a value indicating whether to indent the output. More...

void	need_indent (bool need_indent)
	Sets a value indicating whether to indent the output. More...

void	thread_safe (bool thread_safe)
	Sets a value indicating whether the trace listener is thread safe. More...

virtual void	write_indent ()
	Writes the indent to the listener you create when you implement this class, and resets the NeedIndent property to false. More...

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 ( )

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 )

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

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 )

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

Definition

Constructors

Properties

Methods

Additional Inherited Members

Constructor & Destructor Documentation

◆ default_trace_listener()

Member Function Documentation

◆ assert_ui_enabled() [1/2]

◆ assert_ui_enabled() [2/2]

◆ close()

◆ flush()

◆ log_file_name() [1/2]

◆ log_file_name() [2/2]

◆ write()

◆ write_line()