problem with calling virtual methods?
lazarus / 76-Pas2JS

----------------------------------------------------------------------
mr-highball · 2020-08-22 20:42

pas2js source used is latest trunk pulled 8/22/2020

Trying to implement some classes with pas2js and am noticing an issue
with virtual methods. my example is

parent class defined with a virtual method with no implementation
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
TNyxElementBaseImpl...//declarationprocedure DoUpdateHeight; virtual;
...//implementationprocedure TNyxElementBaseImpl.DoUpdateHeight;begin 
//nothing in baseend 
this parent class, makes a call to the virtual method in this other
method,
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TNyxElementBaseImpl.NotifyHeight(const AType: TPropertyUpdateType; 
const ASize: INyxSize; const AProperty: TSizeProperty);begin  if AType
= puAfterUpdate then    DoUpdateHeight; //  <---------right hereend; 
now, I have a child class which overrides the DoUpdateHeight method
here
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
TNyxElementBrowserImpl = class(TNyxElementBaseImpl,
INyxElementBrowser)...//interfaceprocedure DoUpdateHeight;
override;...//implprocedure
TNyxElementBrowserImpl.DoUpdateHeight;begin  inherited DoUpdateHeight;
// <------- we never get here in the debugger  UpdateSize;end; 
What should be happening is the TNyxElementBrowserImpl.DoUpdateHeight
should be used, not the parent's empty stubbed method... but when
debugging, the parent method is triggered rather than the overridden
child.

Has anyone run into this or spot something that I may be doing
improperly?
any help would be appreciated.

for reference, the full source for the examples are found at these
lines,
parent:
https://github.com/mr-highball/nyx/blob/master/src/nyx.types.pas#L262
https://github.com/mr-highball/nyx/blob/master/src/nyx.types.pas#L1726

child:
https://github.com/mr-
highball/nyx/blob/master/src/nyx.element.browser.pas#L72
https://github.com/mr-
highball/nyx/blob/master/src/nyx.element.browser.pas#L149

----------------------------------------------------------------------
Ñuño_Martínez · 2020-08-23 09:52

It shouldn't be, but did you tried to add SELF. to the calls?  Maybe
the transpiler is forgetting to add this. to it and it may mess up the
thing (never used pas2js though).

BTW, this is to push up this message so more people read it.

----------------------------------------------------------------------
mr-highball · 2020-08-23 19:20

thanks for replying (and for the "bump") @Ñuño_Martínez, I hadn't
thought of trying that, but making the change to Self.DoUpdateHeight
still seems to be calling the parent stub method rather than the
overridden one

----------------------------------------------------------------------
mr-highball · 2020-08-23 20:10

I created this issue in mantis with a test scenario project... but tbh
I couldn't break it in the same way that I'm seeing, and have no idea
what to try next, just posting this for transparency (and the chance
someone spots something I'm not)
https://bugs.freepascal.org/view.php?id=37633

----------------------------------------------------------------------
Ñuño_Martínez · 2020-08-24 09:38

Are you sure you're creating the object with the correct class?  That
question seems silly but it is a quite common mistake (I did it no
long ago ).

----------------------------------------------------------------------
mr-highball · 2020-08-24 13:35

Yeah, to make sure I did a WriteLn of the classname and it indeed was
the child class, but the parent method is being usee (very weird to
try and track down)

----------------------------------------------------------------------
Ñuño_Martínez · 2020-08-25 12:15

Quite weird. Anyway, I had similar bugs and most times the problem was
that I committed a very silly mistake, so silly it is hidden in front
of you.

Let's hope somebody can help.