Creating and Deleting Structs

Structs are created using the $newstruct ProcScript function, but they can also be created implicitly. They are removed when there is no longer a parameter or variable that refers to them.

To create Structs, you can:

Creating Structs

Use the ProcScript function $newstruct to explicitly create a new, empty Struct.
```
vStruct = $newstruct
```
Assign a value to a struct variable or parameter.
```
vStruct1->title = "Users Guide"
```
vStruct now points to a newly created Struct with member title.
For more information, see Assigning Values to Structs.
Assign a value to an allowed Struct function ($name, $index, $parent, or $scalar) or to the $tags Struct.
```
vStruct2->$name = "My Book"
```
vStruct2 created and assigned a name.
Use one of the conversion functions to transform a complex data structure, such as XML, or a Uniface entity to a Struct.
```
params
  xmlstream pXml: in
  struct pStruct: out
endparams

xmlToStruct pStruct, pXml
```
pStruct now points to a (top level) Struct .
Assign an existing Struct to the member of another existing Struct.
```
xmlToStruct pStruct1, pXml  
vStruct2->memberX = pStruct1     
```
memberX is a new Struct, which is a copy of pStruct1

To create or update a Struct member, assign a member to an existing Struct.

If the named Struct exists, it is updated. If it does not, it is created.

variables
  struct vStruct1
  struct vStruct2
endvariables
…
xmlToStruct vStruct1, pXml                     ; Create vStruct1 
…
vStruct1->complexMemberX->memberY = 1         ; Create/update a scalar member
vStruct1->complexMemberX->memberZ = vStruct2  ; Create/update a struct member

Deleting Structs and Members

To delete a Struct, you need to ensure that there are no variables or parameters that refer to it. There is no ProcScript statement to delete a Struct. For local variables, this automatically happens when the entry or operation completes.

The best way to explicitly remove a Struct is to assign an empty value to the struct variable that refers to a Struct.

Example: Assign a new value to the Struct variable that refers to the Struct.

variables
  struct vStruct1, vStruct2
endvariables

vStruct1 = $newstruct
vStruct1->x = "member x"
vStruct1=""

vStruct2 now has no members called x.

Note: When a Struct variable is declared, it is implicitly initialized to Null, so assigning such a Struct variable to an existing Struct variable removes the original Struct. For more information, see Null Values.

Creating and Building a Struct

variables
  struct vStruct, vStructCollection
  string vNames
endvariables

    vNames = "John ;Mary ;Jane"
    while (vNames != "")
        vStruct = $newstruct               ;- Create an empty Struct
        vStruct->name = $itemnr(1, vNames)
        vStructCollection->*{-1} = vStruct ;- append to collection
        delitem vNames, 1
    endwhile
    vStructCollection->$name = "people"
    putmess vStructCollection->$dbgstring  ;- display result in message frame