PureBasic Forums - English

Code: Select all

CompilerIf #PB_Compiler_Backend <> #PB_Backend_C  
  CompilerError "'defer test' needs the C backend (GCC only)"
CompilerEndIf

Macro defer_Pb(func)
! #undef CAT_
! #undef CAT
! #undef defer

! #define CAT_(a, b) a ## b
! #define CAT(a, b) CAT_(a, b)

! #define defer                                                                               \
!     auto void CAT(DEFER_FUNCTION_, __LINE__)(int *);                                        \
!     int CAT(DEFER_VAR_, __LINE__) __attribute__((cleanup(CAT(DEFER_FUNCTION_, __LINE__)))); \
!     void CAT(DEFER_FUNCTION_, __LINE__)(int *)  

! defer { PB_#func; }
EndMacro

Macro defer_My(func)
! #undef CAT_
! #undef CAT
! #undef defer

! #define CAT_(a, b) a ## b
! #define CAT(a, b) CAT_(a, b)

! #define defer                                                                               \
!     auto void CAT(DEFER_FUNCTION_, __LINE__)(int *);                                        \
!     int CAT(DEFER_VAR_, __LINE__) __attribute__((cleanup(CAT(DEFER_FUNCTION_, __LINE__)))); \
!     void CAT(DEFER_FUNCTION_, __LINE__)(int *)  

! defer { f_#func; }
EndMacro

Procedure My_Print(txt$)
  PrintN(txt$)
EndProcedure

Procedure Run()
  defer_Pb(PrintN(L"\npress any key to continue..."))     ;;; L"" needed to output wide-character strings 
  My_Print(~"defer test:\n")                              ;;; if ommited, calling next line: defer_My(my_print(..)) = unresolved external symbol
  defer_My(my_print(L"\nexpected output: 1, 3, 4, 6, 5, 2")) ;;; my_print must be lower case...
  
  PrintN(" 1 ")  
  defer_Pb(PrintN(L" 2 "))
  PrintN(" 3 ")  
  PrintN(" 4 ")
  defer_Pb(PrintN(L" 5 ")) 
  PrintN(" 6 ") 
EndProcedure

OpenConsole()
defer_My(my_print(L"not working in PB's main scope"))
Run()
Input()

Code: Select all

Procedure Something()
  *Buffer = AllocateMemory(2000)
  
  ; do something complicated with memory
  ; ...
  If Complicated Code doesn't work 
    ProcedureReturn
  Else
    ; do something else here.
  EndIf
  
  FreeMemory(*Buffer)  
  
EndProcedure

Code: Select all

Procedure Something()
  *Buffer = AllocateMemory(2000)
  Defer(FreeMemory(*Buffer))
  
  ; do something complicated with memory
  ; ...
  If Complicated Code doesn't work 
    ProcedureReturn
  Else
    ; do something else here.
  EndIf
  
EndProcedure