Re: [Lazarus] how about a HasProperty() property?

2014-01-06 Thread Mailing Lists 





On Sunday 05/01/2014 at 11:51 pm, Alejandro Gonzalo  wrote:






Is there someway else to do that?
Yes, simply use RTTI (Runtime Type Information). See the typinfo unit. 
I've also created an unit for the tiOPF project - it is full of 
extended RTTI helper methods that could make the work much easier. See 
the tiRTTI.pas unit. 
[http://sourceforge.net/p/tiopf/code/ci/tiopf2/tree/Core/tiRTTI.pas] 
Those helper/utility methods could easily be adapted to exclude any 
tiOPF dependencies.


Regards,
 Graeme




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[Lazarus] how about a HasProperty() property?

2014-01-05 Thread Alejandro Gonzalo 
For example, if you want to loop though components and set the dbNavigator's 
DataSource property to that of the component if it has a DataSource property 
(and of course is not a dbNavigator itself).  It seems you can't do that by 
using the component's hierarchy.  Is there someway else to do that?  Components 
do seem to have HasHelp and HasParent properties already.

Perhaps being able to test for the Palate that the component is on would work, 
is there a way to do that?

Thanks.

A. G.
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Re: [Lazarus] how about a HasProperty() property?

2014-01-05 Thread Howard Page-Clark 

On 05/01/2014 23:50, Alejandro Gonzalo wrote:

For example, if you want to loop though components and set the
dbNavigator's DataSource property to that of the component if it has a
DataSource property (and of course is not a dbNavigator itself).  It
seems you can't do that by using the component's hierarchy.  Is there
someway else to do that?  Components do seem to have HasHelp and
HasParent properties already.


Something like this:

uses typinfo;

function ComponentHasProperty(aComponent: TComponent; aProperty: 
string): boolean;

begin
  if not Assigned(aComponent) or (aProperty='') then
Exit(False);
  Result:=GetPropInfo(aComponent, aProperty)nil;
end;

function ClassHasProperty(aClass: TClass; aProperty: string): boolean;
begin
  if (aProperty='') then
Exit(False);
  Result:=GetPropInfo(aClass, aProperty)nil;
end;


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Re: [Lazarus] how about a HasProperty() property?

2014-01-05 Thread Michael Van Canneyt 


Unit typinfo contains:

Function IsPublishedProp(Instance: TObject; const PropName: string): Boolean;
Function IsPublishedProp(AClass: TClass; const PropName: string): Boolean;

That should do what you want.

Michael.

On Mon, 6 Jan 2014, Howard Page-Clark wrote:


On 05/01/2014 23:50, Alejandro Gonzalo wrote:

For example, if you want to loop though components and set the
dbNavigator's DataSource property to that of the component if it has a
DataSource property (and of course is not a dbNavigator itself).  It
seems you can't do that by using the component's hierarchy.  Is there
someway else to do that?  Components do seem to have HasHelp and
HasParent properties already.


Something like this:

uses typinfo;

function ComponentHasProperty(aComponent: TComponent; aProperty: string): 
boolean;

begin
 if not Assigned(aComponent) or (aProperty='') then
   Exit(False);
 Result:=GetPropInfo(aComponent, aProperty)nil;
end;

function ClassHasProperty(aClass: TClass; aProperty: string): boolean;
begin
 if (aProperty='') then
   Exit(False);
 Result:=GetPropInfo(aClass, aProperty)nil;
end;


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