Dec 142017
| Documentation for functions left out of Clipper 5.0’s documentation. Also includes Support Bulletin #3. | |||
|---|---|---|---|
| File Name | File Size | Zip Size | Zip Type |
| MAN500.TXT | 10977 | 2790 | deflated |
| MAN501.TXT | 8473 | 2742 | deflated |
| S50003.TXT | 17011 | 5845 | deflated |
Download File CLIP5NOT.ZIP Here
Contents of the MAN500.TXT file
DECLARE* Create and initialize private memory variables and arrays
DECLARE*
Create and initialize private memory variables and arrays
Syntax: DECLARE
Arguments
If the
as an array. If the
specifying the number of elements for each dimension is either
array[
array[
dimension is 4096.
private variable. An
the in-line assignment operator (:=) followed by any valid Clipper
expression, including a literal array. If no explicit
specified, the variable is given an initial value of NIL. In the case
of an array, each element is NIL. Array identifiers, cannot be given
values with an
A list of variables or arrays can be created and optionally initialized
with one DECLARE statement if each definition is separated by a comma.
Description
DECLARE is a compatibility statement that is a synonym for the PRIVATE
statement. Its general use is not recommended. PRIVATE should be used
in all instances. See PRIVATE for more information.
FIELDBLOCK()
Return a set-get code block for a field variable
Syntax: FIELDBLOCK(
Arguments
Returns
FIELDBLOCK() returns a code block the when evaluated sets (assigns) or
gets (retrieves) the value of the given field. If
not exist in the current work area, FIELDBLOCK() returns NIL.
Description
FIELDBLOCK() is a database function that builds a code block. When
executed with a argument, the code block created by this function
assigns the value of the argument to
without a argument, the code block retrieves the value of
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) // "Kate"
SELECT 2
? EVAL(bFName) // "Cindy"
The function FIELDWBLOCK() provides a set-get block for a field in a
specific work area.
Examples
The following example compares FIELDBLOCK() to a code block created
using the macro operator. Note that using FIELDBLOCK() allows you to
avoid 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.
seealso: "FIELDWBLOCK()" "MEMVARBLOCK()"
FIELDGET()
Retrieve the value of a field using the ordinal position of the
field in the database structure
Syntax: FIELDGET(
Arguments
structure for the current work area.
Returns
FIELDGET() returns the value of the specified field. If
not correspond to the position of any field in the current database
file, FIELDGET() returns NIL.
Description
FIELDGET() is a database function that retrieves the value of a field
using its position within the database file structure rather than its
field name. Within generic database service functions this allows,
among other things, the retrieval of field values without use of the
macro operator.
Examples
The following example compares FIELDGET() to functionally equivalent
code that uses the macro operator to retrieve the value of a field:
LOCAL nField := 1, FName, FVal
USE Customer NEW
//
// Using macro operator
FName := FIELD( nField ) // Get field name
FVal := &FName // Get field value
// Using FIELDGET()
FVal := FIELDGET( nField ) // Get field value
Files: Library is CLIPPER.LIB.
seealso: "FIELDPUT()"
FIELDPUT() Set the value of a field variable
FIELDPUT()
Set the value of a field variable using the ordinal position of
the field in the database structure
Syntax: FIELDPUT(
Arguments
database file.
type of this expression must match the data type of the designated
field variable.
Returns
FIELDPUT() returns the value assigned to the designated field. If
current database file, FIELDPUT() returns NIL.
Description
FIELDPUT() is a database function that assigns
at ordinal position
allows you to set the value of a field using its position within the
database file structure rather than its field name. Within generic
database service functions this allows, among other things, the setting
of field values without use of the macro operator.
Examples
The following example compares FIELDPUT() to functionally equivalent
code that uses the macro operator to retrieve the value of a field:
// Using macro operator
FName := FIELD(nField) // Get field name
FIELD->&FName := FVal // Set field value
// Using FIELDPUT()
FIELDPUT(nField, FVal) // Set field value
Files: Library is CLIPPER.LIB.
seealso: "FIELDGET()"
FIELDWBLOCK() Return a set-get block for a field in a given work area
FIELDWBLOCK()
Return a set-get code block for a field in a given work area
Syntax: FIELDWBLOCK(
Arguments
to specified as a character string.
specified as a numeric value.
Returns
FIELDWBLOCK() returns a code block that when evaluated sets (assigns)
or gets (retrieves) the value of
designated by
specified work area, FIELDWBLOCK() returns NIL.
Description
FIELDWBLOCK() is a database function that builds a code block. When
evaluated with the EVAL() function, the code block first selects the
designated
assigns the value of the argument to
passed, the code block retrieves the value of
original work area is then re-selected before the code block returns
control.
Notes
FIELDWBLOCK() is similar to FIELDBLOCK(), the difference
being that FIELDBLOCK() does not incorporate a fixed work area into
the set-get block.
Examples
The following example compares FIELDWBLOCK() to a code block
created using the macro operator. Note that using FIELDWBLOCK()
allows you to avoid the speed and size overhead of the macro
operator:
// Set-Get block for work area 1 defined with macro operator
bSetGet := &( "{ |setVal| IF( setVal == NIL, ;
1->FName, 1->FName := setVal ) }" )
// Set-Get block defined using FIELDWBLOCK()
// bSetGet created here is the functional equivalent of bSetGet above
bSetGet := FIELDWBLOCK("FName", 1)
Another example of FIELDWBLOCK() can be found in TbDemo.prg,
a sample program included with Clipper 5.0. The TBColumn object,
one of which represents each column in a TBrowse object, requires
among its instance variables a block to retrieve the expression to
be displayed. FIELDWBLOCK() is used to create this block. In the
default installation, TbDemo.prg is located in the \CLIPPER5\SOURCE
directory.
Files: Library is CLIPPER.LIB.
seealso: "FIELDBLOCK()" "MEMVARBLOCK()"
MEMVARBLOCK() Return a set-get code block for a given memory variable
MEMVARBLOCK()
Return a set-get code block for a given memory variable
Syntax: MEMVARBLOCK(
Arguments
refer to specified as a character string.
Returns
MEMVARBLOCK() returns a code block that when evaluated sets (assigns)
or gets (retrieves) the value of the given memory variable. If
Description
The code block created by MEMVARBLOCK() has two operations depending on
whether an argument is passed to the code block when it is evaluated.
If evaluated with an argument, it assigns the value of the argument to
retrieves the value of
Notes
MEMVARBLOCK() creates set-get blocks only for variables
whose names are known at runtime. MEMVARBLOCK(), therefore, cannot
be used to create set-get blocks for local or static variables. The
same restriction applies to creating blocks using the macro (&)
operator.
Examples
The following example compares MEMVARBLOCK() to a code block created
using the macro (&) operator. Note that using MEMVARBLOCK() allows you
to avoid the speed and size overhead of the macro operator:
PRIVATE var := "This is a string"
//
// Set-Get block defined using macro operator
bSetGet := &( "{ |setVal| IF( setVal == NIL, var, var := setVal ) }" )
// Set-Get block defined using MEMVARBLOCK()
// bSetGet created here is the functional equivalent of bSetGet above
bSetGet := MEMVARBLOCK("var")
Files: Library is CLIPPER.LIB.
seealso: "FIELDBLOCK()" "FIELDWBLOCK()"
December 14, 2017
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