call sequence

[hbenrico]

Hi harbour developers,

please have a look at this harbour behavior

a := class1():new() 

a := class1():new() 

those statements call, in sequence:

1) class1 constructor (relative to first assignment)

2) class1 constructor (relative to second assignment)

3) class1 destructor (relative to first assignment)

would it be possible to change the sequence to:

1) class1 constructor (relative to first assignment)

2) class1 destructor (relative to first assigment)

3) class1 constructor (relative to second assignment)

thanks in advance

Enrico

[Maurizio la Cecilia]

Hi Enrico,

just a thought, not tested.

Could you try this:

a := class1():new()

a := nil

a := class1():new() 

The sequence is managed by the garbage collector and the flow is correct, the first object become invalid after the second object instance call.

Best regards.

--

Maurizio

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[hbenrico]

Hello Maurizio...

:) yes I know it works in that way (corrently im using the solution you provided)

just wanted to know if it was possible to implement automatically another call sequence since in the program flow some time I'm forgetting to assign the NIL before reassigning the value 

thank you!!!

Enrico

[Aleksander Czajczynski]

Hi!

New object instance is created before the assignment happens.
Personally, i wouldn't write any code that relies on the order of
destructors. But you can play with preprocessor to always apply NIL in
between. Because why not.

https://os.allcom.pl/hb/3.2/#!eJxdjUFrg0AUhO_vVwzmsgtBSHqzxiIqNGBXWDe5r2abCLKBrKXJv69b2FJzezPzzbzVYPvx62QQXbp-1M7F_SUiWt2nm7Zu1JNBqjMkO6RdxngizDdD2q_jOM7AsctCLPY1XoNgS9qTnKhuiryGJtKeUSHfzNnS2c78k_XiLSrqvG2hCMAxl7D--KjUe1Nib4eJWY6iEa2Sh0I10qdlFRRKxqkSJX5HiJ57f9NJYv1rPy4rdZACzoyfswqVeegf_oboZNx0uz4Ge47Wvr5s_gCnRlh0

In playground it doesn't seem to make any difference, without NIL
assignment, destruction order is the same.

Best regards, Aleksander

--

#include "hbclass.ch"

#xtranslate <a> := <b>():New( <c,...> ) => <a> := NIL ; <a> := (
<b>():New( <c> ) )

LOCAL a

a := T():New( 1 )
a := T():new( 2 )
a := T():new( 3 )

CLASS T
VAR n
METHOD Init(n) CONSTRUCTOR
DESTRUCTOR D()
END CLASS

METHOD Init(n) CLASS T
::n := n
RETURN self

METHOD D() CLASS T
? "destroying", ::n
RETURN self

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[Aleksander Czajczynski]

or even
#xtranslate <a> := <b>():New( <c,...> ) => ( <a> := NIL, <a> := (
<b>():New( <c> ) ) )
that seems to be a bit better than

#xtranslate <a> := <b>():New( <c,...> ) => <a> := NIL ; <a> := (
<b>():New( <c> ) )

for inline expressions.

Aleksander Czajczynski wrote:
> New object instance is created before the assignment happens.
> Personally, i wouldn't write any code that relies on the order of
> destructors. But you can play with preprocessor to always apply NIL in
> between. Because why not.

[...]

[hbenrico]

I was (erroneausly) thinking it would have been better to have an object destroyed before a new one being assigned to the same variable.

now I understand I can't rely on the destructor calls sequence.

I will implement your solution though, playing with preprocessor.

thanks again :)

Enrico-