wxProcess Class Reference

#include <wx/process.h>

Inheritance diagram for wxProcess:

Detailed Description

The objects of this class are used in conjunction with the wxExecute() function.

When a wxProcess object is passed to wxExecute(), its OnTerminate() virtual method is called when the process terminates. This allows the program to be (asynchronously) notified about the process termination and also retrieve its exit status which is unavailable from wxExecute() in the case of asynchronous execution.

Note

If the wxEVT_END_PROCESS event sent after termination is processed by the parent, then it is responsible for deleting the wxProcess object which sent it. However, if it is not processed, the object will delete itself and so the library users should only delete those objects whose notifications have been processed (and call wxProcess::Detach for others). This also means that unless you're going to process the wxEVT_END_PROCESS event, you must allocate the wxProcess class on the heap.

wxProcess also supports IO redirection of the child process. For this, you have to call its Redirect() method before passing it to wxExecute(). If the child process was launched successfully, GetInputStream(), GetOutputStream() and GetErrorStream() can then be used to retrieve the streams corresponding to the child process standard output, input and error output respectively.

Events emitted by this class

The following event handler macros redirect the events to member function handlers 'func' with prototypes like:

void handlerFuncName(wxProcessEvent& event)

Event macros for events emitted by this class:

• EVT_END_PROCESS(id, func):
  Process a wxEVT_END_PROCESS event, sent by wxProcess::OnTerminate upon the external process termination.

Library:  wxBase

Category:  Application and Process Management

wxPerl Note: In wxPerl this class has an additional Destroy method, for explicit destruction.

See Also

wxExecute(), External Program Execution Sample

Public Member Functions
	wxProcess (wxEvtHandler *parent=NULL, int id=-1)
	Constructs a process object.
	wxProcess (int flags)
	Creates an object without any associated parent (and hence no id neither) but allows to specify the flags which can have the value of wxPROCESS_DEFAULT or wxPROCESS_REDIRECT.
virtual	~wxProcess ()
	Destroys the wxProcess object.
void	CloseOutput ()
	Closes the output stream (the one connected to the stdin of the child process).
void	Detach ()
	Detaches this event handler from the parent specified in the constructor (see wxEvtHandler::Unlink() for a similar but not identical function).
wxInputStream *	GetErrorStream () const
	Returns an input stream which corresponds to the standard error output (stderr) of the child process.
wxInputStream *	GetInputStream () const
	It returns an input stream corresponding to the standard output stream of the subprocess.
wxOutputStream *	GetOutputStream () const
	It returns an output stream corresponding to the input stream of the subprocess.
long	GetPid () const
	Returns the process ID of the process launched by Open() or set by wxExecute() (if you passed this wxProcess as argument).
bool	IsErrorAvailable () const
	Returns true if there is data to be read on the child process standard error stream.
bool	IsInputAvailable () const
	Returns true if there is data to be read on the child process standard output stream.
bool	IsInputOpened () const
	Returns true if the child process standard output stream is opened.
virtual void	OnTerminate (int pid, int status)
	It is called when the process with the pid pid finishes.
void	Redirect ()
	Turns on redirection.
void	SetPriority (unsigned priority)
	Sets the priority of the process, between 0 (lowest) and 100 (highest).
Public Member Functions inherited from wxEvtHandler
	wxEvtHandler ()
	Constructor.
virtual	~wxEvtHandler ()
	Destructor.
virtual void	QueueEvent (wxEvent *event)
	Queue event for a later processing.
virtual void	AddPendingEvent (const wxEvent &event)
	Post an event to be processed later.
template<typename T , typename T1 , ... >
void	CallAfter (void(T::*method)(T1,...), T1 x1,...)
	Asynchronously call the given method.
template<typename T >
void	CallAfter (const T &functor)
	Asynchronously call the given functor.
virtual bool	ProcessEvent (wxEvent &event)
	Processes an event, searching event tables and calling zero or more suitable event handler function(s).
bool	ProcessEventLocally (wxEvent &event)
	Try to process the event in this handler and all those chained to it.
bool	SafelyProcessEvent (wxEvent &event)
	Processes an event by calling ProcessEvent() and handles any exceptions that occur in the process.
void	ProcessPendingEvents ()
	Processes the pending events previously queued using QueueEvent() or AddPendingEvent(); you must call this function only if you are sure there are pending events for this handler, otherwise a wxCHECK will fail.
void	DeletePendingEvents ()
	Deletes all events queued on this event handler using QueueEvent() or AddPendingEvent().
virtual bool	SearchEventTable (wxEventTable &table, wxEvent &event)
	Searches the event table, executing an event handler function if an appropriate one is found.
void	Connect (int id, int lastId, wxEventType eventType, wxObjectEventFunction function, wxObject *userData=NULL, wxEvtHandler *eventSink=NULL)
	Connects the given function dynamically with the event handler, id and event type.
void	Connect (int id, wxEventType eventType, wxObjectEventFunction function, wxObject *userData=NULL, wxEvtHandler *eventSink=NULL)
	See the Connect(int, int, wxEventType, wxObjectEventFunction, wxObject*, wxEvtHandler*) overload for more info.
void	Connect (wxEventType eventType, wxObjectEventFunction function, wxObject *userData=NULL, wxEvtHandler *eventSink=NULL)
	See the Connect(int, int, wxEventType, wxObjectEventFunction, wxObject*, wxEvtHandler*) overload for more info.
bool	Disconnect (wxEventType eventType, wxObjectEventFunction function, wxObject *userData=NULL, wxEvtHandler *eventSink=NULL)
	Disconnects the given function dynamically from the event handler, using the specified parameters as search criteria and returning true if a matching function has been found and removed.
bool	Disconnect (int id=wxID_ANY, wxEventType eventType=wxEVT_NULL, wxObjectEventFunction function=NULL, wxObject *userData=NULL, wxEvtHandler *eventSink=NULL)
	See the Disconnect(wxEventType, wxObjectEventFunction, wxObject*, wxEvtHandler*) overload for more info.
bool	Disconnect (int id, int lastId, wxEventType eventType, wxObjectEventFunction function=NULL, wxObject *userData=NULL, wxEvtHandler *eventSink=NULL)
	See the Disconnect(wxEventType, wxObjectEventFunction, wxObject*, wxEvtHandler*) overload for more info.
template<typename EventTag , typename Functor >
void	Bind (const EventTag &eventType, Functor functor, int id=wxID_ANY, int lastId=wxID_ANY, wxObject *userData=NULL)
	Binds the given function, functor or method dynamically with the event.
template<typename EventTag , typename Class , typename EventArg , typename EventHandler >
void	Bind (const EventTag &eventType, void(Class::*method)(EventArg &), EventHandler *handler, int id=wxID_ANY, int lastId=wxID_ANY, wxObject *userData=NULL)
	See the Bind<>(const EventTag&, Functor, int, int, wxObject*) overload for more info.
template<typename EventTag , typename Functor >
bool	Unbind (const EventTag &eventType, Functor functor, int id=wxID_ANY, int lastId=wxID_ANY, wxObject *userData=NULL)
	Unbinds the given function, functor or method dynamically from the event handler, using the specified parameters as search criteria and returning true if a matching function has been found and removed.
template<typename EventTag , typename Class , typename EventArg , typename EventHandler >
bool	Unbind (const EventTag &eventType, void(Class::*method)(EventArg &), EventHandler *handler, int id=wxID_ANY, int lastId=wxID_ANY, wxObject *userData=NULL)
	See the Unbind<>(const EventTag&, Functor, int, int, wxObject*) overload for more info.
void *	GetClientData () const
	Returns user-supplied client data.
wxClientData *	GetClientObject () const
	Returns a pointer to the user-supplied client data object.
void	SetClientData (void *data)
	Sets user-supplied client data.
void	SetClientObject (wxClientData *data)
	Set the client data object.
bool	GetEvtHandlerEnabled () const
	Returns true if the event handler is enabled, false otherwise.
wxEvtHandler *	GetNextHandler () const
	Returns the pointer to the next handler in the chain.
wxEvtHandler *	GetPreviousHandler () const
	Returns the pointer to the previous handler in the chain.
void	SetEvtHandlerEnabled (bool enabled)
	Enables or disables the event handler.
virtual void	SetNextHandler (wxEvtHandler *handler)
	Sets the pointer to the next handler.
virtual void	SetPreviousHandler (wxEvtHandler *handler)
	Sets the pointer to the previous handler.
void	Unlink ()
	Unlinks this event handler from the chain it's part of (if any); then links the "previous" event handler to the "next" one (so that the chain won't be interrupted).
bool	IsUnlinked () const
	Returns true if the next and the previous handler pointers of this event handler instance are NULL.
Public Member Functions inherited from wxObject
	wxObject ()
	Default ctor; initializes to NULL the internal reference data.
	wxObject (const wxObject &other)
	Copy ctor.
virtual	~wxObject ()
	Destructor.
virtual wxClassInfo *	GetClassInfo () const
	This virtual function is redefined for every class that requires run-time type information, when using the wxDECLARE_CLASS macro (or similar).
wxObjectRefData *	GetRefData () const
	Returns the wxObject::m_refData pointer, i.e. the data referenced by this object.
bool	IsKindOf (const wxClassInfo *info) const
	Determines whether this class is a subclass of (or the same class as) the given class.
bool	IsSameAs (const wxObject &obj) const
	Returns true if this object has the same data pointer as obj.
void	Ref (const wxObject &clone)
	Makes this object refer to the data in clone.
void	SetRefData (wxObjectRefData *data)
	Sets the wxObject::m_refData pointer.
void	UnRef ()
	Decrements the reference count in the associated data, and if it is zero, deletes the data.
void	UnShare ()
	This is the same of AllocExclusive() but this method is public.
void	operator delete (void *buf)
	The delete operator is defined for debugging versions of the library only, when the identifier WXDEBUG is defined.
void *	operator new (size_t size, const wxString &filename=NULL, int lineNum=0)
	The new operator is defined for debugging versions of the library only, when the identifier WXDEBUG is defined.

Static Public Member Functions
static bool	Exists (int pid)
	Returns true if the given process exists in the system.
static wxKillError	Kill (int pid, wxSignal sig=wxSIGTERM, int flags=wxKILL_NOCHILDREN)
	Send the specified signal to the given process.
static wxProcess *	Open (const wxString &cmd, int flags=wxEXEC_ASYNC)
	This static method replaces the standard popen() function: it launches the process specified by the cmd parameter and returns the wxProcess object which can be used to retrieve the streams connected to the standard input, output and error output of the child process.
Static Public Member Functions inherited from wxEvtHandler
static void	AddFilter (wxEventFilter *filter)
	Add an event filter whose FilterEvent() method will be called for each and every event processed by wxWidgets.
static void	RemoveFilter (wxEventFilter *filter)
	Remove a filter previously installed with AddFilter().

Additional Inherited Members
Protected Member Functions inherited from wxEvtHandler
virtual bool	TryBefore (wxEvent &event)
	Method called by ProcessEvent() before examining this object event tables.
virtual bool	TryAfter (wxEvent &event)
	Method called by ProcessEvent() as last resort.
Protected Attributes inherited from wxObject
wxObjectRefData *	m_refData
	Pointer to an object which is the object's reference-counted data.

Constructor & Destructor Documentation

wxProcess::wxProcess	(	wxEvtHandler *	parent = NULL,
		int	id = -1
	)

Constructs a process object.

id is only used in the case you want to use wxWidgets events. It identifies this object, or another window that will receive the event.

If the parent parameter is different from NULL, it will receive a wxEVT_END_PROCESS notification event (you should insert EVT_END_PROCESS macro in the event table of the parent to handle it) with the given id.

Parameters

parent	The event handler parent.
id	id of an event.

wxProcess::wxProcess

(

int

flags

)

Creates an object without any associated parent (and hence no id neither) but allows to specify the flags which can have the value of wxPROCESS_DEFAULT or wxPROCESS_REDIRECT.

Specifying the former value has no particular effect while using the latter one is equivalent to calling Redirect().

virtual wxProcess::~wxProcess ( )

virtual

Destroys the wxProcess object.

Member Function Documentation

void wxProcess::CloseOutput

(

)

Closes the output stream (the one connected to the stdin of the child process).

This function can be used to indicate to the child process that there is no more data to be read - usually, a filter program will only terminate when the input stream is closed.

Notice that GetOutputStream() will return NULL after the output stream is closed.

void wxProcess::Detach

(

)

Detaches this event handler from the parent specified in the constructor (see wxEvtHandler::Unlink() for a similar but not identical function).

Normally, a wxProcess object is deleted by its parent when it receives the notification about the process termination.

However, it might happen that the parent object is destroyed before the external process is terminated (e.g. a window from which this external process was launched is closed by the user) and in this case it should not delete the wxProcess object, but should call Detach() instead.

After the wxProcess object is detached from its parent, no notification events will be sent to the parent and the object will delete itself upon reception of the process termination notification.

static bool wxProcess::Exists ( int  pid )

static

Returns true if the given process exists in the system.

See Also

Kill(), Exec sample

wxInputStream* wxProcess::GetErrorStream

(

)

const

Returns an input stream which corresponds to the standard error output (stderr) of the child process.

wxInputStream* wxProcess::GetInputStream

(

)

const

It returns an input stream corresponding to the standard output stream of the subprocess.

If it is NULL, you have not turned on the redirection.

See Also

Redirect().

wxOutputStream* wxProcess::GetOutputStream

(

)

const

It returns an output stream corresponding to the input stream of the subprocess.

If it is NULL, you have not turned on the redirection or already called CloseOutput().

See Also

Redirect().

long wxProcess::GetPid

(

)

const

Returns the process ID of the process launched by Open() or set by wxExecute() (if you passed this wxProcess as argument).

bool wxProcess::IsErrorAvailable

(

)

const

Returns true if there is data to be read on the child process standard error stream.

See Also

IsInputAvailable()

bool wxProcess::IsInputAvailable

(

)

const

Returns true if there is data to be read on the child process standard output stream.

This allows to write simple (and extremely inefficient) polling-based code waiting for a better mechanism in future wxWidgets versions. See the exec sample for an example of using this function.

See Also

IsInputOpened()

bool wxProcess::IsInputOpened

(

)

const

Returns true if the child process standard output stream is opened.

static wxKillError wxProcess::Kill ( int  pid, wxSignal  sig = wxSIGTERM, int  flags = wxKILL_NOCHILDREN  )

static

Send the specified signal to the given process.

Possible signal values can be one of the wxSignal enumeration values.

wxSIGNONE, wxSIGKILL and wxSIGTERM have the same meaning under both Unix and Windows but all the other signals are equivalent to wxSIGTERM under Windows.

The flags parameter can be wxKILL_NOCHILDREN (the default), or wxKILL_CHILDREN, in which case the child processes of this process will be killed too. Note that under Unix, for wxKILL_CHILDREN to work you should have created the process passing wxEXEC_MAKE_GROUP_LEADER.

Returns the element of wxKillError enum.

See Also

Exists(), wxKill(), Exec sample

virtual void wxProcess::OnTerminate ( int  pid, int  status  )

virtual

It is called when the process with the pid pid finishes.

It raises a wxWidgets event when it isn't overridden.

Note that this function won't be called if you Kill() the process.

Parameters

pid	The pid of the process which has just terminated.
status	The exit code of the process.

static wxProcess* wxProcess::Open ( const wxString &  cmd, int  flags = wxEXEC_ASYNC  )

static

This static method replaces the standard popen() function: it launches the process specified by the cmd parameter and returns the wxProcess object which can be used to retrieve the streams connected to the standard input, output and error output of the child process.

If the process couldn't be launched, NULL is returned.

Remarks

In any case the returned pointer should not be deleted, rather the process object will be destroyed automatically when the child process terminates. This does mean that the child process should be told to quit before the main program exits to avoid memory leaks.

Parameters

cmd	The command to execute, including optional arguments.
flags	The flags to pass to wxExecute(). Note: wxEXEC_SYNC should not be used.

Returns

A pointer to new wxProcess object or NULL on error.

See Also

wxExecute()

void wxProcess::Redirect

(

)

Turns on redirection.

wxExecute() will try to open a couple of pipes to catch the subprocess stdio. The caught input stream is returned by GetOutputStream() as a non-seekable stream. The caught output stream is returned by GetInputStream() as a non-seekable stream.

void wxProcess::SetPriority

(

unsigned

priority

)

Sets the priority of the process, between 0 (lowest) and 100 (highest).

It can only be set before the process is created.

The following symbolic constants can be used in addition to raw values in 0..100 range:

• wxPRIORITY_MIN: 0
• wxPRIORITY_DEFAULT: 50
• wxPRIORITY_MAX: 100

Since

2.9.5