HP 3000 Manuals HP 3000 Manuals
Using Intrinsics to Retrieve Variables
The HPCIGETVAR intrinsic returns the current value of the specified
variable from the session variable table. HPCIGETVAR requires only a
variable name. The STATUS parameter is optional. If specified, the
success of the intrinsic call is returned in the STATUS parameter.
Item number and item pairs identify the parameters to receive the
retrieved value. The item number and item pairs that are defined for the
HPCIGETVAR intrinsic are listed below:
0 Ignored by the intrinsic.
1 Indicates that the following parameter receives the integer value
of the variable. If the variable is not an integer, a zero is
returned.
2 Indicates that the following parameter receives the string value
of the variable. If the variable is not a string, ASCII zero is
returned.
3 Indicates that the following parameter receives a 1 if the value
is the boolean TRUE or a 0 if the value is the boolean FALSE. If
the variable is not a boolean, a 0 is returned.
10 Indicates that the following parameter contains the length of the
byte array receiving the variable's string value. If a length is
passed and a byte array is not, an error is returned.
11 Indicates that the following parameter receives the actual length
(in bytes) of the variable's string value.
12 Indicates that the following parameter contains a nonzero value
to dereference the variable recursively. A zero value in this
parameter retrieves the level-1 value of the variable.
13 Indicates that the following parameter receives a 1 if the
variable found is an integer, 2 if the variable found is a
string, or 3 if the variable found is a boolean.
The following example retrieves the current value of the string variable
ANS. The STATUS parameter returns the status of the intrinsic call. The
parameter ANS_LEN returns the length of the string retrieved.
HPCIGETVAR(ANS,STATUS,2,ANS_STRING,11,ANS_LEN);
When you are unsure of the data type of the variable to be retrieved,
several parameters can be included in the intrinsic call. The value is
retrieved and loaded into the appropriate parameter field based on its
type. The variable type parameter (13) is also specified to identify the
actual data type and, therefore, the location of the retrieved value.
The following example identifies parameters for each data type and a
variable type parameter to identify the data type of the retrieved value.
Note that the STATUS parameter has been omitted in this intrinsic call.
HPCIGETVAR(ANS2,,1,ANS2_INTEG,2,ANS2_BYTE,3,ANS2_BOOL,10,ANS2_LEN,13,ANS2_VARTYPE);
Another method of retrieving a variable value when the data type is not
known is shown in the following example. Initially, the HPCIGETVAR
intrinsic call is executed to determine only the data type of the
variable. The retrieved data type is then used to branch to the
appropriate intrinsic statement to retrieve the variable value. In the
following example, the variable type is retrieved and analyzed. If the
ANS2_VARTYPE parameter contains 1, the second intrinsic call is used to
retrieve the integer value.
HPCIGETVAR(ANS2,STATUS,13,ANS2_VARTYPE);
:
HPCIGETVAR(ANS2,STATUS,1,ANS2_INTEG);
The following program sample retrieves the logical device number of the
user's terminal.
_____________________________________________________________________________________
| |
| Function At_Physical_Console : Boolean; |
| Const |
| PhysicalConsoleLDev = 20; |
| KeyWord_GetIntegerValue = 1; { keyword #2 in the intrinsic manual } |
| CIVarNameLen = 9; |
| Type |
| StatusType = Record |
| Case Boolean Of |
| True : ( Error_Num : Integer ); |
| False : ( Info, |
| SubSys : ShortInt ); |
| End; |
| CIVarNameType = Packed Array[ 1..CIVarNameLen ] Of Char; |
| CIVarValueType = Integer; { See constant KeyWord_GetIntegerValue } |
| Var |
| Status : StatusType; |
| CIVarName : CIVarNameType; |
| KeyValue_CIVarValue : CIVarValueType; |
| Procedure HPCIGETVAR; INTRINSIC; |
| Procedure TERMINATE; INTRINSIC; |
| Procedure Check_Status( Var Status : StatusType ); |
| Begin {Check_Status} |
| With Status Do |
| If Info <> 0 Then |
| Begin |
| Writeln( 'Subsystem Number: ', SubSys ); |
| Writeln( 'Info : ', Info ); |
| TERMINATE; |
| End; |
| End; {Check_Status} |
| Begin {At_Physical_Console} |
| CIVarName := 'HPLDEVIN '; { Retrieve the ldev number associated } |
| { with this terminal } |
| { Read the contents of HPLDEVIN variable. } |
| KeyValue_CIVarValue := 0; |
| HPCIGETVAR( CIVarName, Status, |
| KeyWord_GetIntegerValue, KeyValue_CIVarValue ); |
| Check_Status( Status ); |
| At_Physical_Console := KeyValue_CIVarValue = PhysicalConsoleLDev; |
| End; {At_Physical_Console} |
| Begin {Main} |
| If At_Physical_Console Then |
| Writeln( 'Execution of this application on the console is not allowed.' )|
| Else |
| Writeln( 'Not on console -- run the application.' ); |
| End. {Main} |
_____________________________________________________________________________________
Figure 6-2. HPCIGETVAR Intrinsic Example
The FINDJCW intrinsic retrieves the value of a specified JCW variable.
The GETJCW intrinsic retrieves the current value of only the predefined
variable named JCW. Both of these functions can be accomplished with the
HPCIGETVAR intrinsic by specifying the appropriate variable name. To
ensure program readability, use the HPCIGETVAR intrinsic in all cases.