Return more than one variable?

[GeoTrail]

When using ProcedureDLL or just Procedure, can it return more than one variable?

Like this:

Code: Select all

ProcedureReturn Result1$,Result2$

?

[freedimension]

No, but you can use Structures to return multiple values:

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Structure test
  a.l
  b.l
EndStructure

Procedure test(*ReturnMe.test)
  *ReturnMe\a = 42
  *ReturnMe\b = 23
EndProcedure

TestMe.test
TestMe\a =0815
TestMe\b = 4711

test(TestMe)

Debug TestMe\a
Debug TestMe\b

[GeoTrail]

OK, thanks for that

[einander]

When using ProcedureDLL or just Procedure, can it return more than one variable?

Having 2 small arrays as return buffers, you can return numbers or strings easily.

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;Return multiple values from Procedure

Dim Buff.L(10):Dim Buff$(10)  ; Return buffers

Procedure.s DoSomething() 
  Buff(0)=111:  Buff(1)=222  : Buff(2)=333       
  Buff$(0)="Result$ Zero" : Buff$(1)="Result$ One" :Buff$(2)="Result$ Two"
  ProcedureReturn "Here are 6 returns from Procedure DoSomething:"
EndProcedure

Debug DoSomething()

For i=0 to2
  Debug Str(buff(i))+"  "+ buff$(i)
Next

Best regards
Einander

[GeoTrail]

Wow, that looks complicated. Haven't gotten that far in learning PB yet
Thanks anyways

[localmotion34]

why cant you use:

procedure dothis()
var1 =
var2=
procedurereturn var1 and var2
endprocedure

[GeoTrail]

AND
?

Will that work? Has anyone tried that?

[freak]

No, this won't work.

Timo

[blueb]

Wow, that looks complicated. Haven't gotten that far in learning PB yet
Thanks anyways

GeoTrail,

It's not that complicated... In PureBasic arrays are always global. So if you update an array element inside a procedure, it's value will be available anywhere in your program.

HTH,
blueb

[blueznl]

i sometimes do use globals as well to return values from procedures

it all depends on what you do with them, see, if i write one or more procedures that happen to do related stuff, they might share some information... in those caes, i use some specific variable names that are a. unlikely to be used elsewhere, and b. global, and c. shared between the different procedures and have similar functionality

for example:

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Procedure.l x_exist(filename.s)
  Global x_creation.l, x_lastaccess.l, x_lastwrite.l, x_filesize.l
  Protected st.SYSTEMTIME
  ;
  ; *** check if a file exist and if so, retrieve information on a file
  ;
  ; in:     filename.s               - path + filename
  ; retval: 1 #True                  - found and info retrieved
  ;         0 #False                 - not found or cannot get my greedy fingers on it
  ; out:    x_filesize.l             - size of file
  ;         x_creation.l             - when created
  ;         x_lastaccess.l           - when last accessed
  ;         x_lastwrite.l            - last written To
  ;
  file_h = CreateFile_(@filename.s,0,0,0,#OPEN_EXISTING,0,0)    ; open only for retrieval of attributes
  If file_h <> #INVALID_HANDLE_VALUE                            ; ok it exists
    x_filesize.l = GetFileSize_(file_h,0)                       ; that's the size
    ;
    creation.FILETIME                                           ; create temp vars  
    lastaccess.FILETIME
    lastwrite_ft.FILETIME
    st.SYSTEMTIME
    ;
    GetFileTime_(file_h,@creation,@lastaccess,@lastwrite)
    ;
    x_creation.l = x_filetimetodate(@creation)
    x_lastaccess.l = x_filetimetodate(@lastaccess)
    x_lastwrite.l = x_filetimetodate(@lastwrite)
    CloseHandle_(file_h) 
    ProcedureReturn #True
  Else
    ProcedureReturn #False
  EndIf
EndProcedure

all the procedures in my personal library use the following naming scheme: x_whatever... so if i need to return more than one thing from a procedure, i either use x_procedurename_whatever if it's meant to be shared between procedures but i normally don't touch it, or i use x_whatever to return additional information

for example, the procedure above returns x_creation with creation time and date of the file, x_lastaccess, and x_lastwrite

of course it's essential to document this kind of usage, and to declare those variables global

[localmotion34]

ok, so if in a LIB i write with tailbite, i want to create a command that gets an MDI gadget properties and store them in a structure.

basically i want the user to be able to set values for an x, y, width height of an MDI gadget when a window is in a docked position, and then when the window is undocked, the MDI automaticlly resizes to predefined x,y,width,height values in the undocked state.

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Structure dockedproperties
  MDIWidth.l 
  MDIHeight.l 
  MDIdockedx.l
 MDIdockedy.l
EndStructure 

Structure undockedproperties
  MDIWidth.l 
  MDIHeight.l 
  MDIdockedx.l
 MDIdockedy.l
EndStructure 

proceduredll dockedproperties(MDIgadget);this will set the efined values of above structures
endprocedure

proceduredll undockedproperties(

endprocedure

proceduredll flipdockstate(dockhandle,MDIgadget,@docked/undockedproperties)
resizegadget(MDIgadget,----structure here)
endprocedure

this way, quick undocking or docking a window automatically resizes the MDI to values defined in the procedures. basically i want to the user to be able to setup these values just by using the procedures and then flipping the "dock" state.

[El_Choni]

If you only have one docked window, I would store the data in a global structured variable. Otherwise, I would use a structured linked list (if using TailBite, remember to declare the list in a procedure).

[localmotion34]

can you give an example. i thought variables in a library or DLL cant be accessed in PB code?

[Dare2]

Would using Global makes a variable in a dll sortof-kindof public? Ditto in a tailbite lib?

Can't test this myself right at the mo.

[El_Choni]

Yes, you can, by providing a pointer to the variable. But a more clean solution is to give a function that retrieves that value like, for example, WindowID() XD

That is, your DLL/lib code accesses the variable/linkedlist/memory block, and returns it to the main code.

Using Global makes your variable permanent in memory, and public to the same process (even the program calling the DLL/lib) but not by name, but by pointer. Locals are only in the procedure stack.