PascalScript can't use classes like TStringList
lazarus / 5-Lazarus Extra Components

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lainz · 2016-07-09 23:07

Hi, when I try to use a TStringList for example, the application
crashes and gives me a SIGSEV error.

I've already attached the Plugin to the Script, and also it compiles,
so is not a compilation problem of the script but a problem executing
it.

Attached an example. Just uncomment the lines in the SynEdit and try.

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derek.john.evans · 2016-07-10 02:16

Ok, Ive had a look for what its worth. It seems all constructors are
broken. I had a look in uPSRuntime & x86.inc which includes a lot of
FPC specific edits to handle FPC constructor calling conventions, all
of which are beyond my knowledge.

So, I came up with two work arounds:

1) Create an external function which creates the TStringList. ie:

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 function
CreateStringList: TStringList;begin  Result :=
TStringList.Create;end; procedure TForm1.PSScript1Compile(Sender:
TPSScript);begin  PSScript1.AddFunction(@ShowMessage, 'procedure
ShowMessage(m: string);');  PSScript1.AddFunction(@CreateStringList,
'function CreateStringList: TStringList;');end;   
Then this code works:
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 var  s:
TStringList;begin  ShowMessage('This line works.');  s :=
CreateStringList;  s.Add('Test');  ShowMessage(s[0]);  s.Free;end.  
 But, it still will crash if you call the constructor. So:

2) Register a constructor for TStringList which links to the
CreateStringList function:

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
TForm1.PSScript1CompImport(Sender: TObject; x:
TPSPascalCompiler);begin 
x.FindClass('TStringList').RegisterMethod('constructor
Create');end; procedure TForm1.PSScript1ExecImport(Sender: TObject;
se: TPSExec; x: TPSRuntimeClassImporter);begin 
x.FindClass('TStringList').RegisterConstructor(@CreateStringList,
'Create');end;   
This "shouldn't" work but it does for some reason.

Im guessing someone with more knowledge of FPC constructor calling
needs to look at this issue. But, there are 2 workarounds.

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fpcoder · 2016-07-10 06:34

EDIT: My suggestion doesn't work anymore. I use Geepsters workaround
now.

If I remember right, you should edit uPSC_classes.pas so that the
constructor becomes available. There's a {$IFDEF DELPHI2005UP} that
prevents the constructor from being registered. Dont forget to do the
same for the TStrings class! Its in the same file, a bit up.

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
SIRegisterTSTRINGLIST(Cl: TPSPascalCompiler);begin  with
Cl.AddClassN(cl.FindClass('TStrings'), 'TStringList') do 
begin {$IFDEF DELPHI2005UP}    RegisterMethod('constructor
Create;');{$ENDIF}     RegisterMethod('function Find(S:String;var
Index:Integer):Boolean');    RegisterMethod('procedure Sort');   
RegisterProperty('Duplicates', 'TDuplicates', iptrw);   
RegisterProperty('Sorted', 'Boolean', iptrw);   
RegisterProperty('OnChange', 'TNotifyEvent', iptrw);   
RegisterProperty('OnChanging', 'TNotifyEvent', iptrw);  end;end;

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lainz · 2016-07-10 13:39

Thanks Geepster, both workarounds are working.
Kapibara, commenting the ifdef does not works for me, you've tested
it?

Edit: Reported here http://bugs.freepascal.org/view.php?id=30363

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Martin_fr · 2016-07-10 16:03

please test with the upstream/original source.

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lainz · 2016-07-10 16:46

Quote from: Martin_fr on July 10, 2016, 06:03:59 pmplease test with
the upstream/original source.

Yes, it works with the PascalScript downloaded from GitHub.

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fpcoder · 2016-07-11 05:17

@Lainz Yes, a year ago I managed to import the TStringList and use
from inside script, but it involved modifying a line or two of the
source. Unfortunately I cant remember the exact steps.

Looking at the source for the app I wrote, this is how the stringlist
was made available. But it required the modified pascalscript source
which later got accidentally replaced by a fresh unmodified version.

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
TDataParser.OnCompImport(Sender: TObject; ACompiler:
TPSPascalCompiler);begin  SIRegister_Std(ACompiler); 
SIRegisterTObject(ACompiler);  SIRegisterTStrings(ACompiler, True);
//Both are  SIRegisterTStringList(ACompiler);    //needed!!end; 
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
TDataParser.OnExecImport(Sender: TObject; APSExec: TPSExec; 
AClassImporter: TPSRuntimeClassImporter);begin 
RIRegister_Std(AClassImporter);  RIRegisterTObject(AClassImporter); 
RIRegisterTStrings(AClassImporter, True);  //Both are 
RIRegisterTStringList(AClassImporter);     //Needed !!end;

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lainz · 2016-07-12 17:07

I'm now using the GitHub version, I need only to comment one line of
code that don't want to be compiled and that's all. My code works with
no modifications and no need to do OnCompImport and OnExecImport.

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fpcoder · 2016-07-13 01:35

@lainz - Thats great! I want it up and running too and removed lazarus
preinstalled pascalscript and installed the GIT version. For me there
was no error on install except lazarus package EditorMacroScript
needed something from the removed sources. Anyway, I just wanted to
see if it worked, but got SIGSEG in the script on TStringList.Create
even after adding the PSImport_classes plugin to PSScript.

Could you describe more closely what you did, or attach a small sample
that you know works. Maybe its my installation that is wrong.

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lainz · 2016-07-13 01:47

I commented a line when compiling it and also the ide was using the
old package. I deleted the folder under components and replaced with
the git one i downloaded from github. Then i rebuild lazarus.

The first post here contains an attachment that works just uncomment
the lines and run it.

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lainz · 2016-07-13 01:49

Also im using lazarus release not trunk...