Default Values in Structure Definition

[RobertRioja]

I understand that implementation might be difficult, but this would be a useful feature. For example, if you have a database of people, most of whom are from the US:

Code: Select all

Structure Person
  Name.s
  Age.l
  Country.s = "US"
EndStructure

Global People.Person

Now you can leave People.Country alone, or you can set it to another country as needed.

[Demivec]

@RobertRioja: How about this?

Code: Select all

Structure Person
  Name.s
  Age.l
  Country.s
EndStructure

Global DefaultPersonValue.Person: DefaultPersonValue\Country = "US"  ;Define default for Person

Global People.Person = DefaultPersonValue ;Use default
Global OtherPeople.Person                         ;No default

This currently works in PureBasic just the way it is.

[RobertRioja]

Yes, that would work. But it does not really address the original post, about having defaults in a structure. However, I do like your solution.
Thanks,
Robert

[kenmo]

As the author of this request, I don't really have a strong opinion about it 10 years later

Can I show a case where it's *needed*? No, of course not, it's not needed, you can always initialize your values in-line or by a constructor procedure. (But, we also had to *copy* structure values manually, until the team gave us CopyStructure()...)

In retrospect and knowing more about PureBasic, this feature might work nicely if implemented as part of InitializeStructure() -- whether called by the programmer or internally called by PB libraries.

Here's an example of how I imagine it working:

Code: Select all

Structure MySquare
  x.d       ; default to 0.0 as usual
  y.d       ; default to 0.0 as usual
  Width.d   = 5.0
  Height.d  = 5.0
  Scale.d   = 1.0
EndStructure


A.MySquare
Debug A\Scale ; would be 1.0

*B.MySquare = AllocateStructure(MySquare)
Debug *B\Scale ; would be 1.0

*C.MySquare = AllocateMemory(SizeOf(MySquare))
Debug *C\Scale ; would be 0.0 - not yet initialized!
;
InitializeStructure(*C, MySquare)
Debug *C\Scale ; would be 1.0
;
ClearStructure(*C, MySquare)
Debug *C\Scale ; would be cleared to 0.0

[diceman]

That would be a nifty thing, indeed!