FClose()
FCount()
FCreate()
FErase()
FError()
FieldBlock()
FieldName()
FieldPos()
FieldPut()
Tag Archives: FIELDBLOCK()
Variable Management Functions
Variable Management
| FieldBlock | Return a code block that sets/gets a value for a given field |
| FieldWBlock | Return a sets/gets code block for field in a given work area |
| HB_AParams | Returns an array containing values of all parameters passed to a function, method or procedure |
| HB_ArgC | Returns the number of command line arguments |
| HB_ArgCheck | Checks existence of an internal switch on the command line |
| HB_ArgShift | Updates HB_Arg* parameter list removing the 1-st one and replacing it by others |
| HB_ArgString | Retrieves the vale of an internal switch set on the command line. |
| HB_ArgV | Retrieves the value of a command line argument |
| HB_PIsByRef | Determine if a parameter is passed by reference. |
| HB_PValue | Retrieves the value of an argument. |
| HB_ValToStr | Converts any scalar type to a string. |
| MemVarBlock | Returns a codeblock that sets/gets a value of memvar variable |
| PCount | Retrieves the number of arguments passed to a function. |
| Type | Retrieves the type of an expression |
| ValType | Retrieves the data type of an expression |
FieldWBlock()
FIELDWBLOCK()
Return a sets/gets code block for field in a given work area
Syntax
FIELDWBLOCK( <cFieldName>, <nWorkArea> ) --> bFieldBlock
Arguments
<cFieldName> is a string that contain the field name.
<nWorkArea> is the work area number in which <cFieldName> exist.
Returns
FIELDWBLOCK() return a code block that when evaluate could retrieve field value or assigning a new value for a field in a given work area. If <cFieldName> is not specified or from type other than character, or if <nWorkArea> is not specified or is not numeric FIELDWBLOCK() return NIL.
Description
FIELDWBLOCK() return a code block that sets/gets the value of field from a given work area. When this code block is evaluated without any parameters passed then it returns the current value of the given field. If the code block is evaluated with a parameter, than its value is used to set a new value to the field, this value is also return by the block. If the block is evaluate and there is no field with the name <cFieldName> in work area number <nWorkArea>, the code block return NIL.
Examples
LOCAL bField
// this block work on the field "name" that exist on work area 2
bFiled := FIELDBLOCK( "name", 2 )
// open a file named One in work area 1
// that have a field named "name"
SELECT 1
USE one
// open a file named Two in work area 2
// it also have a field named "name"
SELECT 2
USE two
SELECT 1
? "Original names: ", One->name, Two->name
? "Name value for file Two :", EVAL( bField )
EVAL( bField, "Two has new name" )
? "and now: ", One->name, Two->name
Compliance
If the block is evaluate and there is no field with the name <cFieldName> in the given work area, the code block return NIL.
CA-Cl*pper would raise BASE/1003 error if the field does not exist.
Files
Library is rtl
Seealso
EVAL(), FIELDBLOCK(), MEMVARBLOCK()
FieldBlock()
FIELDBLOCK()
Return a code block that sets/gets a value for a given field
Syntax
FIELDBLOCK( <cFieldName> ) --> bFieldBlock
Arguments
<cFieldName> is a string that contain the field name.
Returns
FIELDBLOCK() return a code block that when evaluate could retrieve a field value or assigning a new value to the field. If <cFieldName> is not specified or from type other than character, FIELDBLOCK() return NIL.
Description
FIELDBLOCK() return a code block that sets/gets the value of field. When this code block is evaluated without any parameters passed then it returns the current value of the given field. If the code block is evaluated with a parameter, than its value is used to set a new value to the field, this value is also return by the block. If the block is evaluate and there is no field with the name <cFieldName> in the current work area, the code block return NIL.
Note that FIELDBLOCK() works on the current work area, if you need a specific work area code block use FIELDWBLOCK() instead.
Examples
// open a file named Test that have a field named "name"
LOCAL bField
bFiled := FIELDBLOCK( "name" )
USE Test
? "Original value of field 'name' :", EVAL( bField )
EVAL( bField, "Mr X new name" )
? "New value for the field 'name' :", EVAL( bField )
Compliance
If the block is evaluate and there is no field with the name <cFieldName> in the current work area, the code block return NIL.
CA-Cl*pper would raise BASE/1003 error if the field does not exist.
Files
Library is rtl
Seealso
EVAL(), FIELDWBLOCK(), MEMVARBLOCK()
C5_FIELDBLOCK
FIELDBLOCK()
Return a set-get code block for a given field
------------------------------------------------------------------------------
Syntax
FIELDBLOCK(<cFieldName>) --> bFieldBlock
Arguments
<cFieldName> is the name of the field to which the set-get block
will refer.
Returns
FIELDBLOCK() returns a code block that, when evaluated, sets (assigns)
or gets (retrieves) the value of the given field. If <cFieldName> does
not exist in the specified work area, FIELDBLOCK() returns an empty
block.
Description
FIELDBLOCK() is a database function that builds a code block. When
executed with an argument, the code block created by this function
assigns the value of the argument to <cFieldName>. When executed
without an argument, the code block retrieves the value of <cFieldName>.
Note that the specified field variable may not exist when the code block
is created, but must exist before the code block is executed.
Notes
. Work area: The code block returned by FIELDBLOCK() sets or
gets the value of the specified field in whatever work area is
current when the block is run. For example, given work areas 1 and
2, both containing field FName:
SELECT 1
FName:= "Kate"
SELECT 2
FName := "Cindy"
bFName := FIELDBLOCK("FName")
SELECT 1
? EVAL(bFName) // Result: "Kate"
SELECT 2
? EVAL(bFName) // Result: "Cindy"
The function FIELDWBLOCK() provides a set-get block for a field in a
specific work area.
Examples
. This example compares FIELDBLOCK() to a code block created
using the macro operator. Note that using FIELDBLOCK() avoids the
speed and size overhead of the macro operator:
// Set-Get block defined using macro operator
bSetGet := &( "{ |setVal| IF( setVal == NIL,;
FName, FName := setVal ) }" )
// Set-Get block defined using FIELDBLOCK()
// bSetGet created here is the functional
// equivalent of bSetGet above
bSetGet := FIELDBLOCK("FName")
Files Library is CLIPPER.LIB.
See Also: FIELDWBLOCK() MEMVARBLOCK()
Code blocks, inside and out
Code blocks, inside and out
