[Implemented] Initial value for static variables

[tinman]

Otherwise there is no way to initialise them to anything other than zero.

Sure, you can do this:

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Procedure foo()
    Static a
    Static a_initialised
    
    If a_initialised=0
        a = 1
        a_initialised = 1
    EndIf
    
    Debug a
    
    a = a + 1
EndProcedure


foo()
foo()
foo()
foo()
foo()

End

But that kinda sucks.

[benny]

Hey Tinman,

that is what I asked some months ago ... but noone replied

viewtopic.php?t=9922

[Froggerprogger]

It would be great to can write:

Global myVar.l = 2000
Protected bla.l = 12

and as well

Static bumm.l = 5 ; called each procedure call
or
InitStatic bumm.l = 5 ; called just during the first procedure call

-> so:
1st : the syntax : xxx varName.type = 12345 would be WONDERFUL
2nd : InitStatic could do the job you requested

(just an idea)

[tinman]

@benny:

Sorry, I had a look in the search but I could not find it, otherwise I would have added to your topic.

It would be great to can write:

Global myVar.l = 2000
Protected bla.l = 12

and as well

Static bumm.l = 5 ; called each procedure call

I would much rather have that syntax used to initialise the static the first time the procedure is called, otherwise there isn't much point to being able to use statics like this the way you suggest. Their value would always be reset to, in this case 5. Of course if you're returning a pointer to a static then it might be useful. But I'd prefer not to have to use another keyword just to initialise them.

[LarsG]

... Static bumm.l = 5 ; called each procedure call..

uuuh.. wouldn't that kind of defeat it's purpose?!?
Maybe you'd rather make it protected, and set it to 5 each call?!?

[benny]

@Tinman:
Yup ... no prob ... maybe this thread gets recognized by more ppl !

For this reason I just quote what I have written in the older thread :

...
Would it be possible, to pass e.g. to a STATIC variable something like an initial value. ATM every declared variable is 0.

Lets say, that this would be possible :

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STATIC a.l = 10 

(maybe also for GLOBAL, PROTECTED and SHARED).

This would make the following easier

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 and the DEBUG-Result would be 11 and 12 ! ... 
[code]

Procedure Test() 
  Static a.l = 10 
  a.l + 1 
  ProcedureReturn a.l 
EndProcedure 

Debug Test() 
Debug Test() 
 

So, most important for me would be what Tinman said, too. To have just an initial value the first time the procedure is called!

[GedB]

I would like to see this feature, too.

I'd also like the optioin of using a function, for more complicated initialisations.

For example:

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Procedure Init_A() 
  if this
    a = 10
  elseif that
    a = 20
  else
    a = 30
  endif
  ProcedureReturn a
EndProcedure

Procedure Test() 
  Static a.l = Init_A()
  a.l + 1 
  ProcedureReturn a.l 
EndProcedure 
Debug Test() 
Debug Test() 

[blueznl]

the problem with these kind of things is: when should it be executed? the immediately at the start of the program? when the procedure is first time run?

pb runs top to bottom, so a global would work

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global a = 5

however, with a procedure it's a slightly different matter:

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procedure test()
  static a = 5
endprocedure

with a simple value being assigned, it doesn't matter if the value is assigned on the start of the program or the first call of the procedure

in the following situation, however, things matter:

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global x = 0
;
procedure test1()
  x = x+1
endprocedure
;
procedure test2()
  static z = test(1)
endprocedure
;
debug x
test1()
debug x

if it would be assigned on program start (without the procedure having been called, which is my preference) this would output

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1
2

if it would be assigned upon first call of the procedure, it would output

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0
1

[blueznl]

and while we're at it, how about a 'regional' variation?

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StartRegion
Regional a = 1             ; a and b only exists and are considered global
Regional b = 22           ; inside the startregion / endregion statements
;
Procedure test()
  a = a+1                    ; a is a regional variable
EndProcedure
;
EndRegion

an alternative keyword might be Local, an alternative syntax might be the following:

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Global z = 1
;
; z is now 1
;
Local z = 2
;
; old z is hidden, new z is now 2
;
EndLocal z
;
; z is now 1 again
;

or, perhaps a better syntax:

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Local z = 100
;
FreeLocal z

[blueznl]

resuming:

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global a             ; defines a global var but doesn't change the value
global a = 5         ; defines a as global AND changes the value
static a             ; defines a as static with initial value of 0
static a = 5         ; defines a as static with an initial value of 5
protected a          ; defines a as protected with initial value of 0
protected a = 5      ; defines a as protected with an initial value of 5

- static can only be used ONE time per variable per procedure
- global can be reused with or without assignment
- static with assignment can only use constants / expressions without vars or procedure calls

[Froggerprogger]

@LarsG
You're right - there would be no advantage of introducing InitStatic, Static could do it itself.

(blueznl wrote:)

the problem with these kind of things is: when should it be executed? the immediately at the start of the program? when the procedure is first time run?

It should be executed when it appears in the chronological order of the program's execution.
Keep in mind that:

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global a.l = myProc()

should mean the same as:

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global a.l : a = myProc()

and so as well:

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static a.l = myProc()

should mean the same as:

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If FirstCallOfThisProcedure 
  static a.l : a = myProc()
EndIf

So I don't see the problem not to use Procedure-return-values / vars for static initialization.

[blueznl]

frogger, that's a matter of logic and taste as long as fred chooses a consistent variant, it doesn't matter to me

(although, for my feeling, i'd rather say: all statics are initialized at code start, not procedure execution, but it's all a matter of taste)

[Froggerprogger]

OK, clear
But here are the question I ask myself:

1. Which choice gives us the wider variety of coding-possibilities ?
Therefore Static initialized by Procedures/Vars would be the choice.
Because then we could call Procedures and use vars for initialization.

2. Consistence: How would Initializations of "Global a.l = ..." and "Protected a.l = ..." be handled ?
They would be called when appearing in code, so in program's execution order. Static should do also, so when it's 'line' appears during first call of the procedure.

3. What is more easy to implement ?
I think all of these ways are relative easy to implement, because it seems to be just like a 'syntax-wrapping' to me. (wrap a functionality of more complex syntax with a more easy one.)

4. Downgrade-compatibility ?
All of these versions are downgrade-compatible, because the syntax: "Global/Static/... myVarname.type = ..." is not valid atm.

[freak]

Keep in mind that:

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global a.l = myProc()

should mean the same as:

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global a.l : a = myProc()

It's not that simple. Keep in mind that in a dll, Global commands are written
outside of procedures, and thus in an area where this would never be
executed. So the initialisation has to be moved to a place, where it will
be executed.

and so as well:

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static a.l = myProc()

should mean the same as:

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If FirstCallOfThisProcedure 
  static a.l : a = myProc()
EndIf

Hum, this means an unneccesary slowdown of the procedure, don't you think?
If static variables were simple initialized at program start, you don't
need such a check.


I think allowing only a constant value for initialisation is the easiest and
most consistent to implement.

Timo

[blueznl]

well, freak, that one time intialisation is all i need, other solutions won't hurt me but might be slower (no, never!) and more difficult to implement

but you're right, if a static is initialised at the beginning of the code, it's not going to do any checks when entering a procedure and thus is faster

i know what i want