|
HP OpenVMS Systems Documentation |
|
HP BASIC for OpenVMS
|
| Previous | Contents | Index |
A variant comprises two or more fields of a record that provide alternative descriptions for the same portion of a record.
The following is an example of a CDDL data definition containing variant fields and the corresponding HP BASIC RECORD statement:
define record CDD$top.basic.variant_example
description is
/* test simple variant */.
variant_example structure.
my_string datatype text size 9.
variants.
variant.
my_s_real datatype f_floating.
my_d_real datatype d_floating.
end variant.
variant.
my_g_real datatype g_floating.
my_h_real datatype h_floating.
end variant.
end variants.
my_byte datatype signed byte.
end variant_example structure.
end variant_example.
|
1 %INCLUDE %FROM %CDD "CDD$TOP.BASIC.VARIANT_EXAMPLE"
C1 ! test simple variant
C1 RECORD VARIANT_EXAMPLE ! UNSPECIFIED
C1 STRING MY_STRING = 9 ! TEXT
C1 VARIANT
C1 CASE
C1 SINGLE MY_S_REAL ! F_FLOATING
C1 DOUBLE MY_D_REAL ! D_FLOATING
C1 CASE
C1 GFLOAT MY_G_REAL ! G_FLOATING
C1 HFLOAT MY_H_REAL ! H_FLOATING
C1 END VARIANT
C1 BYTE MY_BYTE ! SIGNED BYTE
C1 END RECORD
|
CDD/Repository data definitions sometimes contain VARIANTS OF field
description statements as well as simple variants. A CDDL or CDO
VARIANTS OF statement names a tag variable whose value at run time
determines which of the variant fields is the current variant.
HP BASIC does not support the VARIANTS OF statement. If a
CDD/Repository data definition containing a VARIANTS OF statement is
extracted, HP BASIC signals the informational message,
"<number> tag value from CDD/Repository ignored" and
treats the VARIANTS OF as an ordinary variant and ignores the tag value.
21.8 NAME FOR BASIC Clause
HP BASIC supports the CDDL and CDO field attribute clause NAME FOR BASIC.
The field attribute clause NAME FOR BASIC declares a facility-specific name for a field. For example:
name for basic is "subject_name$" |
When you assign a name using the NAME FOR BASIC clause in a CDDL or CDO data definition, HP BASIC recognizes only this name when you refer to the field. Note that when you use the NAME FOR BASIC clause, you can place dollar sign ($) and percent sign (%) suffixes in your RECORD statement field names.
The following example is a CDDL data definition containing the NAME FOR BASIC clause and the corresponding HP BASIC RECORD statement.
define record city_study
description is
/* This example formats data resulting from a
study on the relationship between place of birth
and earning potential */.
info structure.
subject_name datatype text size 10
name for basic is "subject_name$".
birth_city datatype text size 10
name for basic is "city_of_birth$".
salary datatype signed byte
name for basic is "salary%".
end info structure.
end city_study.
|
1 %INCLUDE %FROM %CDD "CDD$TOP.BASIC.CITY_STUDY" C1 ! This example formats data resulting from a C1 ! study on the relationship between place of birth C1 ! and earning potential C1 RECORD INFO ! UNSPECIFIED C1 STRING SUBJECT_NAME$ = 10 ! TEXT C1 STRING CITY_OF_BIRTH$ = 10 ! TEXT C1 BYTE SALARY% ! SIGNED BYTE C1 END RECORD |
The NAME FOR BASIC clause enables you to assign completely different names to the same field. |
For more information about the CDDL NAME FOR BASIC field attribute
clause, see the CDD/Repository documentation.
21.9 CDD/Repository Data Types
HP BASIC supports a subset of CDD/Repository data types, as shown in Table 21-1.
| Data Type | HP BASIC Translation |
|---|---|
| TEXT | STRING |
| SIGNED BYTE | BYTE |
| SIGNED WORD | WORD |
| SIGNED LONGWORD | LONG |
| F_FLOATING | SINGLE |
| D_FLOATING | DOUBLE |
| G_FLOATING | GFLOAT |
| PACKED DECIMAL | DECIMAL |
If a CDD/Repository data definition containing an unsupported data type is extracted, HP BASIC signals the informational message "Datatype in CDD/Repository not supported, substituted group for: <field-name>" and translates the data type by creating a group to contain the data type field. The group name is the name of the unsupported data type followed by the text "_VALUE". This allows you to access the field name within the group.
An example of how HP BASIC translates unsupported CDD/Repository data types is shown in the following CDDL data definition and corresponding HP BASIC RECORD statement:
define record CDD$top.basic.stock
description is
/* this is an example data definition that contains
data types not supported by HP BASIC */.
stock structure.
product_no datatype is text
size is 8 characters.
date_ordered datatype is date.
status_code datatype is unsigned byte.
quantity datatype is unsigned longword
aligned on longword.
location array 1:4
datatype is text
size is 30 characters.
unit_price datatype is longword.
end stock structure.
end stock.
|
1 %INCLUDE %FROM %CDD "CDD$TOP.BASIC.STOCK"
C1 ! This is an example data definition that contains
C1 ! data types not supported by HP BASIC
C1 RECORD STOCK ! UNSPECIFIED
C1 STRING PRODUCT_NO = 8 ! TEXT
C1 GROUP DATE_ORDERED ! DATE
C1 STRING STRING_VALUE = 8
C1 END GROUP
C1 GROUP STATUS_CODE ! UNSIGNED BYTE
C1 BYTE BYTE_VALUE
C1 END GROUP
C1 STRING FILL = 3
C1 GROUP QUANTITY ! UNSIGNED LONGWORD
C1 LONG LONG_VALUE
C1 END GROUP
C1 STRING LOCATION(1 TO 4) = 30 ! TEXT
C1 GROUP UNIT_PRICE ! UNSIGNED LONGWORD
C1 LONG LONG_VALUE
C1 END GROUP
C1 END RECORD
%BASIC-I-CDDSUBGRO, data type in CDD/Repository not supported,
substituted group for: STOCK::DATE_ORDERED.
%BASIC-I-CDDSUBGRO, data type in CDD/Repository not supported,
substituted group for: STOCK::STATUS_CODE.
%BASIC-I-CDDSUBGRO, data type in CDD/Repository not supported,
substituted group for: STOCK::QUANTITY.
%BASIC-I-CDDSUBGRO, data type in CDD/Repository not supported,
substituted group for: STOCK::UNIT_PRICE.
|
Table 21-2 describes CDD/Repository data types not supported by HP BASIC and their translation.
| Data Type | HP BASIC Translation |
|---|---|
| UNSIGNED BYTE |
GROUP CDD/Repository-field-name
BYTE BYTE_VALUE END GROUP |
| UNSIGNED WORD |
GROUP CDD/Repository-field-name
WORD WORD_VALUE END GROUP |
| UNSIGNED LONGWORD |
GROUP CDD/Repository-field-name
LONG LONG_VALUE END GROUP |
| SIGNED QUADWORD |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = 8 END GROUP |
| UNSIGNED QUADWORD |
GROUPCDD/Repository-field-name
STRING STRING_VALUE = 8 END GROUP |
| SIGNED OCTAWORD |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = 16 END GROUP |
| UNSIGNED OCTAWORD |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = 16 END GROUP |
| H_FLOATING |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = 16 END GROUP |
| F_FLOATING COMPLEX |
GROUP CDD/Repository-field-name
SINGLE SINGLE_R_VALUE SINGLE SINGLE_I_VALUE END GROUP |
| D_FLOATING COMPLEX |
GROUP CDD/Repository-field-name
DOUBLE DOUBLE_R_VALUE DOUBLE DOUBLE_I_VALUE END GROUP |
| G_FLOATING COMPLEX |
GROUP CDD/Repository-field-name
GFLOAT GFLOAT_R_VALUE GFLOAT GFLOAT_I_VALUE END GROUP |
| H_FLOATING COMPLEX |
GROUP CDD/Repository-field-name
HFLOAT HFLOAT_R_VALUE HFLOAT HFLOAT_I_VALUE END GROUP |
| ZONED NUMERIC |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = length END GROUP |
| UNSIGNED NUMERIC |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = length END GROUP |
| LEFT SEPARATE NUMERIC |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = length + 1 END GROUP |
|
LEFT OVERPUNCHED
NUMERIC |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = length END GROUP |
| RIGHT SEPARATE NUMERIC |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = length + 1 END GROUP |
|
RIGHT OVERPUNCHED
NUMERIC |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = length END GROUP |
| VARYING STRING |
GROUP CDD/Repository-field-name
WORD WORD_VALUE STRING STRING_VALUE = length END GROUP |
| BIT 1 |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = length /8 END GROUP |
| DATE |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = 8 END GROUP |
| POINTER |
GROUP CDD/Repository-field-name
LONG LONG_VALUE END GROUP |
| UNSPECIFIED |
GROUP CDD/Repository-field-name
STRING STRING_VALUE = length END GROUP |
| VIRTUAL FIELD | Ignored |
The following sections describe how HP BASIC translates
CDD/Repository data types.
21.9.1 Character String Data Types
There are two CDD/Repository character string data types, TEXT and VARYING STRING. The TEXT data type translates directly into the HP BASIC STRING data type. VARYING STRING is not a supported HP BASIC data type; therefore, HP BASIC creates a group to contain the field.
The following example is a CDD/Repository definition that contains both the TEXT and VARYING STRING data types and the translated HP BASIC RECORD statement:
| Example 21-1 CDDL |
|---|
define record CDD$top.basic.strings
description is
/* test */.
basicstrings structure.
abc datatype is text size is 10.
xyz datatype is varying string size is 16.
end basicstrings structure.
end strings.
|
| Example 21-2 Translated RECORD Statement |
|---|
1 %INCLUDE %FROM %CDD "CDD$TOP.BASIC.STRINGS"
C1 ! test
C1 RECORD BASICSTRINGS ! UNSPECIFIED
C1 STRING ABC = 10 ! TEXT
C1 GROUP XYZ ! VARYING STRING
C1 WORD WORD_VALUE
C1 STRING STRING_VALUE = 16
C1 END GROUP
C1 END RECORD
................1
%BASIC-I-CDD/SUBGRO, 1: data type in CDD/Repository not supported,
substituted group for: BASICSTRINGS::XYZ.
|
In the VARYING STRING data type, the actual character string is preceded by a 16-bit count field. Therefore, HP BASIC creates a WORD variable to hold the specified string length.
The count field preceding the VARYING STRING is actually an UNSIGNED WORD. Therefore, the count field of a VARYING STRING whose length is greater than 32,767 is interpreted by HP BASIC as a negative number. |
In the previous example, the group name (XYZ) is the same name as a CDD/Repository field. Therefore, HP BASIC supplies an additional name for the RECORD components. The supplied names are WORD_VALUE and STRING_VALUE. For example, the following program statement creates an instance of the record BASICSTRINGS, called MY_REC:
100 MAP (TEST) BASICSTRINGS MY_REC |
The names you use to reference these components in HP BASIC are
MY_REC::XYZ::WORD_VALUE and MY_REC::XYZ::STRING_VALUE.
21.9.2 Integer Data Types
CDD/Repository refers to integer data types as fixed-point data types. CDD/Repository supports BYTE, WORD, LONGWORD, QUADWORD, and OCTAWORD integer data types. Each of these data types can have the following additional attributes:
SIGNED
UNSIGNED
SIZE
DIGITS
FRACTION
BASE
SCALE
In CDDL, if integer data types are not specified as being signed or unsigned, the default is unsigned. HP BASIC supports only signed BYTE, signed WORD, signed LONGWORD, and signed QUADWORD integers. If a CDD/Repository data definition containing an unsigned BYTE, WORD, LONGWORD, or QUADWORD integer is extracted, HP BASIC signals the informational message "Datatype in CDD/Repository not supported, substituted group for: <field-name>," and creates a group to contain the field. Because the group name is the same as the CDD/Repository field name, HP BASIC assigns a new name to the field. This is shown in the following CDDL data definition and corresponding HP BASIC RECORD statement:
define record CDD$top.basic.integers
description is
/*Test of selected integer data types*/.
basicint structure.
my_byte datatype is signed byte.
my_ubyte datatype is byte.
my_word datatype is signed word.
my_uword datatype is unsigned word.
my_long datatype is signed longword.
my_ulong datatype is unsigned longword.
end basicint structure.
end integers.
|
1 %INCLUDE %FROM %CDD "CDD$TOP.BASIC.INTEGERS"
C1 ! Test of selected integer data types
C1 RECORD BASICINT ! UNSPECIFIED
C1 BYTE MY_BYTE ! SIGNED BYTE
C1 GROUP MY_UBYTE ! UNSIGNED BYTE
C1 BYTE BYTE_VALUE
C1 END GROUP
C1 WORD MY_WORD ! SIGNED WORD
C1 GROUP MY_UWORD ! UNSIGNED WORD
C1 WORD WORD_VALUE
C1 END GROUP
C1 LONG MY_LONG ! SIGNED LONGWORD
C1 GROUP MY_ULONG ! UNSIGNED LONGWORD
C1 LONG LONG_VALUE
C1 END GROUP
C1 END RECORD
................1
%BASIC-I-CDDSUBGRO, 1: data type in CDD/Repository not supported,
substituted group for: BASICINT::MY_UBYTE.
%BASIC-I-CDDSUBGRO, 1: data type in CDD/Repository not supported,
substituted group for: BASICINT::MY_UWORD.
%BASIC-I-CDDSUBGRO, 1: data type in CDD/Repository not supported,
substituted group for: BASICINT::MY_ULONG.
|
When the previous data definition is extracted from CDD/Repository, HP BASIC signals an informational message for each of the unsigned data types, and names the CDD/Repository unsigned byte field BYTE_VALUE, the CDD/Repository unsigned word field WORD_VALUE, and the CDD/Repository unsigned longword field LONG_VALUE.
HP BASIC does not support OCTAWORD integers. If a CDD/Repository definition contains an OCTAWORD integer, HP BASIC signals the informational message "Datatype in CDD/Repository not supported, substituted group for: <field-name>" and creates a group to contain the field and a string component within the group. The string component is 16 bytes for OCTAWORD integers. For example:
define record CDD$top.basic.bigintegers
description is
/*Test of quadword and octaword integer data types*/.
basicint structure.
my_quad datatype is signed quadword.
my_octa datatype is signed octaword.
end basicint structure.
end bigintegers.
|
1 %INCLUDE %FROM %CDD "CDD$TOP.BASIC.BIGINTEGERS"
C1 ! Test of quadword and octaword integer data types
C1 RECORD BASICINT ! UNSPECIFIED
C1 QUAD MY_QUAD ! SIGNED QUADWORD
C1 GROUP MY_OCTA ! SIGNED OCTAWORD
C1 STRING STRING_VALUE = 16
C1 END GROUP
C1 END RECORD
%BASIC-I-CDDSUBGRO, data type in CDD/Repository not supported,
substituted group for: BASICINT::MY_OCTA.
|
CDD/Repository supports the SCALE keyword to specify an implied exponent in integer data types, and the BASE keyword (supported in CDDL only) to specify that the scale for a fixed-point field is to be interpreted in a numeric base other than 10. HP BASIC does not support these integer attributes. Therefore, HP BASIC signals the informational message "CDD/Repository specifies SCALE for <name>. Not supported" for fixed-point fields containing a SCALE specification, and the error message "CDD/Repository attributes for <name> are other than base 10" for fixed-point fields specifying a base other than 10. For example:
define record CDD$top.basic.funnyintegers
description is
/* Test of quadword and octaword integer data types */.
basicint structure.
my_byte datatype is signed byte scale 2.
my_long datatype is signed longword base 8.
end basicint structure.
end funnyintegers.
|
1 %INCLUDE %FROM %CDD "CDD$TOP.BASIC.FUNNYINTEGERS"
C1 ! Test of quadword and octaword integer data types
C1 RECORD BASICINT ! UNSPECIFIED
C1 GROUP MY_BYTE ! SIGNED BYTE
C1 BYTE BYTE_VALUE
C1 END GROUP
C1 LONG MY_LONG ! SIGNED LONGWORD
C1 END RECORD
%BASIC-I-CDDATTSCA, CDD specifies SCALE for BASICINT::MY_BYTE. Not supported
%BASIC-E-CDDATTBAS, CDD attributes for BASICINT::MY_LONG are other than base 10
|
At compilation time, HP BASIC also signals these warning errors for each reference to fields that are not base 10 or that have a SCALE.
| Previous | Next | Contents | Index |