dx-doc 1:4.4.4-7 / usr / share / doc / dx / help / dxall1154

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#!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