#!F-adobe-helvetica-medium-r-normal--18*
#!N
#!CSeaGreen #!N #!Rsetvars
Setting Variables #!N #!EC #!N #!N DXLink enables a program to
set (and retrieve) Data Explorer values in a visual program or
macro. It is important to understand the distinction between a Data
Explorer object and a Data Explorer value. A Data Explorer object
is the basic data structure of the Data Explorer data model
(see #!Ldatmod,dxall197 h Understanding the Data Model #!EL in IBM Visualization Data Explorer User's Guide). A Data
Explorer value is a character representation of a Data Explorer object
(as would be used in the scripting language). The following are
common examples of Data Explorer values: #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N
string: "123" #!N integer: 123 #!N scalar: 1.23 #!N vector: [1
2 3] #!N string list: { "123", "456" } #!N integer
list: { 123, 456 } #!N scalar list: { 1.23, 4.56
} #!N vector list: { [1 2 3 ], [4 5
6] } #!EF #!N #!N #!EC #!N #!N Not all Data
Explorer objects can be represented by strings (e.g., fields and groups).
#!N #!I0 #!N #!N #!I0 #!N #!F-adobe-times-bold-r-normal--18* #!F-adobe-times-bold-r-normal--18* DXLError DXLSetValue(DXLConnection *conn,
const char *varname, #!EF const char *value) #!EF #!I50 #!N Sets
the global variable specified by #!F-adobe-times-bold-r-normal--18* *varname #!EF to the value
given in #!F-adobe-times-bold-r-normal--18* *value #!EF (double quotation marks--for strings and string
lists-- must be escaped with a backslash (\), as in the
example below.) Returns OK or ERROR. #!N #!N This function is
used primarily to set global variables in a macro and is
the mechanism to set "inputs" to a module in a program.
#!I0 #!N #!N #!N #!N Global variables are variables that have
been assigned or referenced outside a macro (the global scope) or
are defined by a reference in a nested scope. Variables assigned
with a nested scope are considered local. For example, in the
following macro, the variables #!F-adobe-times-bold-r-normal--18* a #!EF and #!F-adobe-times-bold-r-normal--18* b #!EF
are local to the macro (their first occurrence is an assignment),
while #!F-adobe-times-bold-r-normal--18* c #!EF is a global variable (its first occurrence
is a reference). #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N macro foo( )
--> ( ) #!N { #!N a = "1"; #!N b
= c; #!N . . . . #!N } #!N foo(
); #!EF #!N #!N #!EC #!N #!N See #!Lvuim,dxall556 h Variables Used in Macros #!EL in IBM
Visualization Data Explorer User's Guide for the rules of scoping variables.
#!N #!N You might use DXLSetValue to control the name of
a data set imported with the Import tool, as in the
following Data Explorer macro: #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N #!N macro
main( ) #!N { #!N object = Import(MyFileNameHere); #!N .... #!N
Display(...) #!N } #!EF #!N #!N #!EC #!N #!N The following
C code invokes the main macro to import data from the
file foobar.dx and render it: #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N #!N
. . . #!N DXLSetValue(conn, "MyFileNameHere", "\"foobar.dx\""); #!N DXLExecuteOnce(conn); #!N .
. . #!EF #!N #!N #!EC #!N #!N The Data Explorer
user interface provides a convenient mechanism for placing global variables in
a visual program. The DXLInput tool (see #!Ldxlinpt,dxall802 h DXLInput #!EL in IBM Visualization
Data Explorer User's Reference) implements a global variable inside the macro
main( ). By changing the label in the #!F-adobe-times-bold-r-normal--18* Notation #!EF
field of the DXLInput tool's configuration dialog box, you can change
the name of the global variable. This mechanism provides a clean
interface between the visual program and the DXLink application. Named DXLInput
tools are simply placed in the program and connected to the
module input that needs to be controlled from the application. In
the preceding example, a DXLInput tool named MyFileNameHere would be connected
to the first input of the Import tool. Then, the same
piece of C code could be used to control the program.
#!N #!N #!CForestGreen #!N #!F-adobe-courier-bold-r-normal--18* #!F-adobe-times-bold-r-normal--18* #!N DXLError DXLSetInteger(DXLConnection *conn, const
char *varname, int value) #!N DXLError DXLSetScalar(DXLConnection *conn, const char *varname,
#!N const double value) #!N DXLError DXLSetString(DXLConnection *conn, const char *varname,
#!N const char *value) #!EF #!EF #!N #!N #!EC #!N #!N
Set the variable specified by #!F-adobe-times-bold-r-normal--18* *varname #!EF to #!F-adobe-times-bold-r-normal--18* value
#!EF (or #!F-adobe-times-bold-r-normal--18* *value #!EF ). These are convenience functions that
use DXLSetValue. They return OK or ERROR. #!N #!N #!N #!F-adobe-times-medium-i-normal--18*
Next Topic #!EF #!N #!N #!Lall1154,dxall1155 h Retrieving Values Sent From Data Explorer #!EL #!N #!F-adobe-times-medium-i-normal--18* #!N
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