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FIELDBLOCK()
Return a set-get code block for a given field
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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()
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