SET TYPEAHEAD

SET TYPEAHEAD

Set the size of the keyboard buffer

Syntax

      SET TYPEAHEAD TO <nKeyboardSize>

Arguments

TO <nKeyboardSize> specifies the number of keystrokes the keyboard buffer can hold from a minimum of zero to a maximum of 4096. The default size of the keyboard buffer is machine-dependent but 16 is the minimum size.

Description

SET TYPEAHEAD defines the size of the Clipper keyboard buffer that caches keystrokes input directly by the user. SET TYPEAHEAD, however, does not affect the number of characters that can be stuffed programmatically using the KEYBOARD command. When executed, SET TYPEAHEAD clears the keyboard buffer and sets the size to <nKeyboardSize>.

When TYPEAHEAD is SET TO zero, keyboard polling is suspended. An explicit request for keyboard input, however, will temporarily enable the keyboard and read any pending keystrokes from the BIOS buffer. Calling NEXTKEY() constitutes such an explicit request. NEXTKEY() reads any pending keystrokes from the BIOS buffer and returns the INKEY() value of the first keystroke read, or zero if no keystrokes are pending.

Seealso

ALTD(), CLEAR, TYPEAHEAD, INKEY(), KEYBOARD, NEXTKEY()

C5_Functions

 AADD()          Add a new element to the end of an array
 ABS()           Return the absolute value of a numeric expression
 ACHOICE()       Execute a pop-up menu
 ACLONE()        Duplicate a nested or multidimensional array
 ACOPY()         Copy elements from one array to another
 ADEL()          Delete an array element
 ADIR()*         Fill a series of arrays with directory information
 AEVAL()         Execute a code block for each element in an array
 AFIELDS()*      Fill arrays with the structure of the current database file
 AFILL()         Fill an array with a specified value
 AINS()          Insert a NIL element into an array
 ALERT()         Display a simple modal dialog box
 ALIAS()         Return a specified work area alias
 ALLTRIM()       Remove leading and trailing spaces from a character string
 ALTD()          Invoke the CA-Clipper debugger
 ARRAY()         Create an uninitialized array of specified length
 ASC()           Convert a character to its ASCII value
 ASCAN()         Scan an array for a value or until a block returns true (.T.)
 ASIZE()         Grow or shrink an array
 ASORT()         Sort an array
 AT()            Return the position of a substring within a character string
 ATAIL()         Return the highest numbered element of an array
 BIN2I()         Convert a 16-bit signed integer to a numeric value
 BIN2L()         Convert a 32-bit signed integer to a numeric value
 BIN2W()         Convert a 16-bit unsigned integer to a numeric value
 BOF()           Determine when beginning of file is encountered
 BREAK()         Branch out of a BEGIN SEQUENCE...END construct
 BROWSE()*       Browse records within a window
 CDOW()          Convert a date value to a character day of the week
 CHR()           Convert an ASCII code to a character value
 CMONTH()        Convert a date to a character month name
 COL()           Return the screen cursor column position
 COLORSELECT()   Activate attribute in current color settings
 CTOD()          Convert a date string to a date value
 CURDIR()        Return the current DOS directory
 DATE()          Return the system date as a date value
 DAY()           Return the day of the month as a numeric value
 DBAPPEND()      Append a new record to the database in the current work area
 DBCLEARFIL()    Clear a filter condition
 DBCLEARIND()    Close all indexes for the current work area
 DBCLEARREL()    Clear active relations
 DBCLOSEALL()    Close all occupied work areas
 DBCLOSEAREA()   Close a work area
 DBCOMMIT()      Flush pending updates
 DBCOMMITALL()   Flush pending updates in all work areas
 DBCREATE()      Create a database file from a database structure array
 DBCREATEIND()   Create an index file
 DBDELETE()      Mark a record for deletion
 DBEDIT()        Browse records in a table layout
 DBEVAL()        Evaluate code block for each record matching scope/condition
 DBF()*          Return current alias name
 DBFIELDINFO()   Return and optionally change information about a field
 DBFILEGET()     Insert the contents of a field into a file
 DBFILEPUT()     Insert the contents of a file into a field
 DBFILTER()      Return the current filter expression as a character string
 DBGOBOTTOM()    Move to the last logical record
 DBGOTO()        Position record pointer to a specific identity
 DBGOTOP()       Move to the first logical record
 DBINFO()        Return and optionally change database file information
 DBORDERINFO()   Return and optionally change order and index file information
 DBRECALL()      Reinstate a record marked for deletion
 DBRECORDINFO()  Return and optionally change information about a record
 DBREINDEX()     Recreate all active indexes for the current work area
 DBRELATION()    Return the linking expression of a specified relation
 DBRLOCK()       Lock the record at the current or specified identity
 DBRLOCKLIST()   Return an array of the current lock list
 DBRSELECT()     Return the target work area number of a relation
 DBRUNLOCK()     Release all or specified record locks
 DBSEEK()        Move to the record having the specified key value
 DBSELECTAR()    Change the current work area
 DBSETDRIVER()   Return the database driver and optionally set a new driver
 DBSETFILTER()   Set a filter condition
 DBSETINDEX()    Empty orders from an order bag into the order list
 DBSETORDER()    Set the controlling order
 DBSETRELAT()    Relate two work areas
 DBSKIP()        Move relative to the current record
 DBSTRUCT()      Create an array containing the structure of a database file
 DBUNLOCK()      Release all locks for the current work area
 DBUNLOCKALL()   Release all locks for all work areas
 DBUSEAREA()     Use a database file in a work area
 DELETED()       Return the deleted status of the current record
 DESCEND()       Create a descending index key value
 DEVOUT()        Write a value to the current device
 DEVOUTPICT()    Write a value to the current device using a picture clause
 DEVPOS()        Move the cursor or printhead to a new position
 DIRCHANGE()     Change the current DOS directory
 DIRECTORY()     Create an array of directory and file information
 DIRMAKE()       Create a directory
 DIRREMOVE()     Remove a directory
 DISKCHANGE()    Change the current DOS disk drive
 DISKNAME()      Return the current DOS drive
 DISKSPACE()     Return the space available on a specified disk
 DISPBEGIN()     Begin buffering screen output
 DISPBOX()       Display a box on the screen
 DISPCOUNT()     Return the number of pending DISPEND() requests
 DISPEND()       Display buffered screen updates
 DISPOUT()       Write a value to the display
 DOSERROR()      Return the last DOS error number
 DOW()           Convert a date value to a numeric day of the week
 DTOC()          Convert a date value to a character string
 DTOS()          Convert a date value to a string formatted as yyyymmdd
 EMPTY()         Determine if the result of an expression is empty
 EOF()           Determine when end of file is encountered
 ERRORBLOCK()    Post a code block to execute when a runtime error occurs
 ERRORLEVEL()    Set the CA-Clipper return code
 EVAL()          Evaluate a code block
 EXP()           Calculate e**x
 FCLOSE()        Close an open binary file and write DOS buffers to disk
 FCOUNT()        Return the number of fields in the current .dbf file
 FCREATE()       Create and/or truncate a binary file to zero-length
 FERASE()        Delete a file from disk
 FERROR()        Test for errors after a binary file operation
 FIELD()         Return a field name from the current database (.dbf) file
 FIELDBLOCK()    Return a set-get code block for a given field
 FIELDGET()      Retrieve the value of a field using the field position
 FIELDNAME()     Return a field name from the current database (.dbf) file
 FIELDPOS()      Return the position of a field in a work area
 FIELDPUT()      Set the value of a field variable using the field position
 FIELDWBLOCK()   Return a set-get code block for a field in a given work area
 FILE()          Determine if files exist in the default directory or path
 FKLABEL()*      Return function key name
 FKMAX()*        Return number of function keys as a constant
 FLOCK()         Lock an open and shared database file
 FOPEN()         Open a binary file
 FOUND()         Determine if the previous search operation succeeded
 FREAD()         Read characters from a binary file into a buffer variable
 FREADSTR()      Read characters from a binary file
 FRENAME()       Change the name of a file
 FSEEK()         Set a binary file pointer to a new position
 FWRITE()        Write to an open binary file
 GETACTIVE()     Return the currently active Get object
 GETAPPLYKEY()   Apply a key to a Get object from within a reader
 GETDOSETKEY()   Process SET KEY during GET editing
 GETENV()        Retrieve the contents of a DOS environment variable
 GETPOSTVALID()  Postvalidate the current Get object
 GETPREVALID()   Prevalidate a Get object
 GETREADER()     Execute standard READ behavior for a Get object
 HARDCR()        Replace all soft carriage returns with hard carriage returns
 HEADER()        Return the current database file header length
 I2BIN()         Convert a CA-Clipper numeric to a 16-bit binary integer
 IF()            Return the result of an expression based on a condition
 IIF()           Return the result of an expression based on a condition
 INDEXEXT()      Return index extension defined by the current database driver
 INDEXKEY()      Return the key expression of a specified index
 INDEXORD()      Return the order position of the controlling index
 INKEY()         Extract a character from the keyboard buffer or a mouse event
 INT()           Convert a numeric value to an integer
 ISALPHA()       Determine if the leftmost character in a string is alphabetic
 ISCOLOR()       Determine if the current computer has color capability
 ISDIGIT()       Determine if the leftmost character in a string is a digit
 ISLOWER()       Determine if the leftmost character is a lowercase letter
 ISPRINTER()     Determine whether LPT1 is ready
 ISUPPER()       Determine if the leftmost character in a string is uppercase
 L2BIN()         Convert a CA-Clipper numeric value to a 32-bit binary integer
 LASTKEY()       Return INKEY() value of last key extracted from the keyboard
 LASTREC()       Determine the number of records in the current .dbf file
 LEFT()          Extract substring beginning with first character in a string
 LEN()           Return the length of a string or number of array elements
 LOG()           Calculate the natural logarithm of a numeric value
 LOWER()         Convert uppercase characters to lowercase
 LTRIM()         Remove leading spaces from a character string
 LUPDATE()       Return the last modification date of a database (.dbf) file
 MAX()           Return the larger of two numeric or date values
 MAXCOL()        Determine the maximum visible screen column
 MAXROW()        Determine the maximum visible screen row
 MEMOEDIT()      Display or edit character strings and memo fields
 MEMOLINE()      Extract a line of text from a character string or memo field
 MEMOREAD()      Return the contents of a disk file as a character string
 MEMORY()        Determine the amount of available free pool memory
 MEMOSETSUPER()  Set an RDD inheritance chain for the DBFMEMO database driver
 MEMOTRAN()      Replace carriage return/linefeeds in character strings
 MEMOWRIT()      Write a character string or memo field to a disk file
 MEMVARBLOCK()   Return a set-get code block for a given memory variable
 MENUMODAL()     Activate a top bar menu
 MIN()           Return the smaller of two numeric or date values
 MLCOUNT()       Count the number of lines in a character string or memo field
 MLCTOPOS()      Return position of a string based on line and column position
 MLPOS()         Determine the position of a line in a string or memo field 
 MOD()*          Return the dBASE III PLUS modulus of two numbers
 MONTH()         Convert a date value to the number of the month
 MPOSTOLC()      Return line/ column position of a string based on a position
 NETERR()        Determine if a network command has failed
 NETNAME()       Return the current workstation identification
 NEXTKEY()       Read the pending key in the keyboard buffer 
 NOSNOW()        Toggle snow suppression
 ORDBAGEXT()     Return the default order bag RDD extension
 ORDBAGNAME()    Return the order bag name of a specific order
 ORDCOND()       Specify conditions for ordering
 ORDCONDSET()    Set the condition and scope for an order
 ORDCREATE()     Create an order in an order bag
 ORDDESCEND()    Return and optionally change the descending flag of an order
 ORDDESTROY()    Remove a specified order from an order bag
 ORDFOR()        Return the FOR expression of an order
 ORDISUNIQUE()   Return the status of the unique flag for a given order
 ORDKEY()        Return the key expression of an order
 ORDKEYADD()     Add a key to a custom built order
 ORDKEYCOUNT()   Return the number of keys in an order
 ORDKEYDEL()     Delete a key from a custom built order
 ORDKEYGOTO()    Move to a record specified by its logical record number
 ORDKEYNO()      Get the logical record number of the current record
 ORDKEYVAL()     Get key value of the current record from controlling order
 ORDLISTADD()    Add orders to the order list
 ORDLISTCLEAR()  Clear the current order list
 ORDLISTREBUI()  Rebuild all orders in the order list of the current work area
 ORDNAME()       Return the name of an order in the order list
 ORDNUMBER()     Return the position of an order in the current order list
 ORDSCOPE()      Set or clear the boundaries for scoping key values
 ORDSETFOCUS()   Set focus to an order in an order list
 ORDSETRELAT()   Relate a specified work area to the current work area
 ORDSKIPUNIQUE() Move record pointer to the next or previous unique key
 OS()            Return the operating system name
 OUTERR()        Write a list of values to the standard error device
 OUTSTD()        Write a list of values to the standard output device
 PAD()           Pad character, date, and numeric values with a fill character
 PCOL()          Return the current column position of the printhead
 PCOUNT()        Determine the position of the last actual parameter passed
 PROCLINE()      Return source line number of current or previous activation
 PROCNAME()      Return name of the current or previous procedure or function
 PROW()          Return the current row position of the printhead
 QOUT()          Display a list of expressions to the console
 RAT()           Return the position of the last occurrence of a substring
 RDDLIST()       Return an array of the RDDs
 RDDNAME()       Return name of RDD active in current or specified work area
 RDDSETDEFAULT() Set or return the default RDD for the application
 READEXIT()      Toggle Up arrow and Down arrow as READ exit keys
 READFORMAT()    Return and optionally set code block to implement format file
 READINSERT()    Toggle the current insert mode for READ and MEMOEDIT()
 READKEY()*      Determine what key terminated a READ
 READKILL()      Return and optionally set whether current READ can be exited
 READMODAL()     Activate a full-screen editing mode for a GetList
 READUPDATED()   Determine whether any GET variables changed during a READ
 READVAR()       Return the current GET/MENU variable name
 RECCOUNT()*     Determine the number of records in the current database file
 RECNO()         Return the identity at the position of the record pointer
 RECSIZE()       Determine the record length of a database (.dbf) file
 REPLICATE()     Return a string repeated a specified number of times
 RESTSCREEN()    Display a saved screen region to a specified location
 RIGHT()         Return a substring beginning with the rightmost character
 RLOCK()         Lock the current record in the active work area
 ROUND()         Return a numeric value rounded to a specified number of digits
 ROW()           Return the screen row position of the cursor
 RTRIM()         Remove trailing spaces from a character string
 SAVESCREEN()    Save a screen region for later display
 SCROLL()        Scroll a screen region up or down, right or left
 SECONDS()       Return the number of seconds elapsed since midnight
 SELECT()        Determine the work area number of a specified alias
 SET()           Inspect or change a system setting
 SETBLINK()      Toggle * interpretation between blinking/background intensity
 SETCANCEL()     Toggle Alt+C and Ctrl+Break as program termination keys
 SETCOLOR()      Return the current colors and optionally set new colors
 SETCURSOR()     Set the cursor shape
 SETKEY()        Assign an action block to a key
 SETMODE()       Change display mode to a specified number of rows and columns
 SETPOS()        Move the cursor to a new position
 SETPRC()        Set PROW() and PCOL() values
 SOUNDEX()       Convert a character string to "soundex" form
 SPACE()         Return a string of spaces
 SQRT()          Return the square root of a positive number
 STR()           Convert a numeric expression to a character string
 STRTRAN()       Search and replace characters within a string or memo field
 STUFF()         Delete and insert characters in a string
 SUBSTR()        Extract a substring from a character string
 TIME()          Return the system time
 TONE()          Sound a speaker tone for a specified frequency and duration
 TRANSFORM()     Convert any value into a formatted character string
 TRIM()          Remove trailing spaces from a character string
 TYPE()          Determine the type of an expression
 UPDATED()       Determine whether a GET changed during a READ
 UPPER()         Convert lowercase characters to uppercase
 USED()          Determine whether a database file is in USE
 VAL()           Convert a character number to numeric type
 VALTYPE()       Determine the data type returned by an expression
 VERSION()       Returns CA-Clipper version
 WORD()*         Convert CALL command numeric parameters from double to int
 YEAR()          Convert a date value to the year as a numeric value

C5_ALTD

 ALTD()
 Invoke the Clipper debugger
------------------------------------------------------------------------------
 Syntax

     ALTD([<nAction>]) --> NIL

 Arguments

     <nAction> defines what action ALTD() performs when invoked.  The
     following is a complete list of <nAction> values and their actions:

     ALTD() Actions
     ------------------------------------------------------------------------
     Argument     Action
     ------------------------------------------------------------------------
     None         Invokes the debugger if it is enabled
     0            Disables Alt+D
     1            Enables Alt+D
     Other        No action
     ------------------------------------------------------------------------

 Returns

     ALTD() always returns NIL.

 Description

     ALTD() performs differently depending on its argument as shown in the
     table above.  For more information on using the debugger, refer to
     "Clipper Debugger-CLD.LIB" chapter in the Programming and Utilities
     Guide.  Also refer to the "Debugging Your Applications" chapter in the
     Workbench User Guide.

 Examples

     .  This example demonstrates a series of manifest constants that
        can be used as arguments for ALTD() before invoking the debugger
        programmatically:

        #define ALTD_DISABLE      0
        #define ALTD_ENABLE      1
        //
        ALTD(ALTD_ENABLE)

 Files   Library is CLIPPER.LIB.

See Also: SET ESCAPE SETCANCEL()



C5 Error Handling

C5 Error Handling Commands, Statements and Funtions

Statement :

BEGIN SEQUENCE :

Define a sequence of statements for a BREAK

BEGIN SEQUENCE
    <statements>...
    [BREAK [<exp>]]
    <statements>...
    [RECOVER [USING <idVar>]]
    <statements>...
END [SEQUENCE]

Functions :

ALTD() :

Invoke the Clipper Debugger

ALTD( [ <nAction> ] ) --> NIL

BREAK() :

Branch out of a BEGIN SEQUENCE…END construct

BREAK( <exp> ) --> NIL

DOSERROR() :

Return the DOS error number

DOSERROR( [ <nNewOsCode> ] ) --> nOsCode

ERRORBLOCK() :

Post a code block to execute when a runtime error occurs

ERRORBLOCK( [ <bErrorHandler> ] ) --> bCurrentErrorHandler

ERRORLEVEL() :

Set the Clipper return code

ERRORLEVEL( [ <nNewReturnCode> ] ) --> nCurrentReturnCode

NETERR() :

Determine if a network command has failed

NETERR( [ <lNewError> ] ) --> lError

OUTERR() :

Write a list of values to the standard error device

OUTERR( <exp list> ) --> NIL

PROCLINE() :

Return the source line number of the current or previous activation

PROCLINE( [ <nActivation> ] ) --> nSourceLine

PROCNAME() :

Return the name of the current or previous procedure or user-defined function

PROCNAME( [ <nActivation> ] ) --> cProcedureName

Error Class :

Provides objects containing information about runtime errors.

Description :

An Error object is a simple object that contains information pertaining to a runtime error. Error objects have no methods, only exported instance variables. When a runtime error occurs, CA-Clipper creates a new Error object and passes it as an argument to the error handler block specified with the ERRORBLOCK() function. Within the error handler, the Error object can then be queried to determine the nature of the error condition.

Error objects can also be returned to the RECOVER statement of a BEGIN SEQUENCE construct with a BREAK statement. Here, the error object can be queried for local error handling. For more detailed information and examples refer to the Error Handling Strategies chapter in the Programming and Utilities guide.

Class Function :

ErrorNew() :

Returns a new Error object.

ErrorNew() --> objError

Exported Instance Variables :

args (Assignable) :

An array of function or operator arguments.

Contains an array of the arguments supplied to an operator or function when an argument error occurs. For other types of errors, Error:args contains a NIL value.

canDefault (Assignable) :

Indicates whether or not default recovery is available.

Contains a logical value indicating whether the subsystem can perform default error recovery for the error condition. A value of true (.T.) indicates that default recovery is available. Availability of default handling and the actual default recovery strategy depends on the subsystem and the error condition. The minimum action is simply to ignore the error condition.

Default recovery is requested by returning false (.F.) from the error block invoked to handle the error. Note that Error:canDefault is never true (.T.) if Error:canSubstitute is true (.T.).

canRetry (Assignable) :

Indicates whether or not a retry is possible after an error.

Contains a logical value indicating whether the subsystem can retry the operation that caused the error condition. A value of true (.T.) indicates that a retry is possible. Retry may or may not be available, depending on the subsystem and the error condition.

Retry is requested by returning true (.T.) from the error block invoked to handle the error. Note that Error:canRetry never contains true (.T.) if Error:canSubstitute contains true (.T.).

canSubstitute (Assignable) :

Indicates if a new result can be substituted after an error

Contains a logical value indicating whether a new result can be substituted for the operation that produced the error condition. Argument errors and certain other simple errors allow the error handler to substitute a new result value for the failed operation. A value of true (.T.) means that substitution is possible.

The substitution is performed by returning the new result value from the code block invoked to handle the error. Note that Error:canSubstitute is never true (.T.) if either Error:canDefault or Error:canRetry is true (.T.).

cargo (Assignable) :

User-definable variable.

Contains a value of any data type unused by the Error system. It is provided as a user-definable slot, allowing arbitrary information to be attached to an Error object and retrieved later.

description (Assignable) :

Character description of the error condition.

Contains a character string that describes the error condition. A zero-length string indicates that the subsystem does not provide a printable description for the error. If Error:genCode is not zero, a printable description is always available.

filename (Assignable) :

Name of the file associated with the error

Contains a character value representing the name originally used to open the file associated with the error condition. A zero-length string indicates either that the error condition is not associated with a particular file or that the subsystem does not retain filename information.

genCode (Assignable) :

Error code number.

Contains an integer numeric value representing a CA-Clipper generic error code. Generic error codes allow default handling of similar errors from different subsystems. A value of zero indicates that the error condition is specific to the subsystem and does not correspond to any of the generic error codes. The header file, Error.ch, provides a set of manifest constants for generic error codes.

operation (Assignable) :

Character description of the failed operation.

Contains a character string that describes the operation being attempted when the error occurred. For operators and functions, Error:operation contains the name of the operator or function. For undefined variables or functions, it contains the name of the variable or function. A zero-length string indicates that the subsystem does not provide a printable description of the operation.

osCode (Assignable) :

Operating system error code number

Contains an integer numeric value representing the operating system error code associated with the error condition. A value of zero indicates that the error condition was not caused by an error from the operating system. When Error:osCode is set to a value other than zero DOSERROR() is updated with the same value.

Error:osCode properly reflects the DOS extended error code for file errors. This allows proper distinction between errors which result from sharing violations (e.g., opening EXCLUSIVE when another process has already opened the file) and access violations (e.g., opening read/write when the file is marked read-only).

For a list of DOS error codes please look at here 

severity (Assignable) :

Indicates error severity

Contains a numeric value indicating the severity of the error condition. Four standard values are defined in Error.ch:

Error:severity Values
------------------------------------------------------------
Error.ch        Meaning
------------------------------------------------------------
ES_WHOCARES     The condition does not represent a failure;
                the error is informational.
ES_WARNING      The condition does not prevent further
                operations, but may result in a more serious 
                error later. 
ES_ERROR        The condition prevents further operations without 
                corrective action of some kind. 
ES_CATASTROPHIC The condition requires immediate termination 
                of the application.
------------------------------------------------------------

Note that the Clipper runtime support code only generates errors with severities of ES_WARNING or ES_ERROR

subCode (Assignable) :

Subsystem-specific error code number.

Contains an integer numeric value representing a subsystem-specific error code. A value of zero indicates that the subsystem does not assign any particular number to the error condition.

subSystem (Assignable) :

Character description of the subsystem generating the error.

Contains a character string representing the name of the subsystem generating the error. For errors with basic CA-Clipper operators and functions, the subsystem name “BASE” is given. For errors generated by a database driver, Error:subSystem contains the name of the database driver

tries (Assignable) :

Number of times the failed operation has been attempted.

Contains an integer numeric value representing the number of times the failed operation has been attempted. When Error:canRetry is true (.T.), Error:tries can be used to limit the number of retry attempts. A value of zero indicates that the subsystem does not track the number of times the operation has been tried.

Examples :

. This example demonstrates how a file open operation might be handled in an error handler replicating the default CA-Clipper behavior. When, for example, an attempt to open a database file with a USE command fails, control returns to the statement following the offending command:

#include "Error.ch"
#command RETRY => RETURN (.T.) // Retry operation
#command RESUME => RETURN (.F.) // Default recovery
//
FUNCTION MyError( objError )
   //
   // Handle file open error
   IF objError:genCode == EG_OPEN .AND.;
      objError:canDefault .AND.;
      NETERR()
   //
      RESUME
   ENDIF
  .
  . <other error statements>
  .
RETURN NIL

. This example retries an operation within an error handler a specified number of times:

 #include "Error.ch"
 #command RETRY => RETURN (.T.) // Retry operation
 #command RESUME => RETURN (.F.) // Default recovery
 //
FUNCTION MyError( objError )

 // Handle printer not ready error
 IF objError:genCode == EG_PRINT .AND.;
    objError:canRetry .AND.;
    objError:tries < 25

    RETRY
 ENDIF
 .
 . <other error statements>
 .
 RETURN NIL

. This code fragment returns an error object from an error handler to the RECOVER statement for further processing:

LOCAL objLocal, bLastHandler
// Save current and set new error handler
bLastHandler := ERRORBLOCK({ |objErr| ;
MyHandler(objErr, .T.)})
BEGIN SEQUENCE
   .
   . <operation that might fail>
   .
   RECOVER USING objLocal
   .
   . <send messages to objLocal and handle the error>
   .
END
// Restore previous error handler
ERRORBLOCK( bLastHandler )
FUNCTION MyHandler( objError, lLocalHandler )

    // Handle locally returning the error object
    IF lLocalHandler
       BREAK objError
    ENDIF
    .
    . <other statements to handle the error>
    .
RETURN NIL

Files: Header file is Error.ch, default error handler is in Errorsys.prg.