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Python bool represented in delphi
Joined: 12 Aug 2005
Posts: 7
Python bool represented in delphi
Hi,
I`ve just upgraded P4D from 3.27 to 3.29 (currently using Delphi 5)
In my app I have a tag database accessible from python with SetValue(tagname,value) and GetValue(tagname)
(all values are represented by double`s inside the delphi app)
With P4D 3.27 SetValue(tagname,True) sets the tagdatabase value to 1, while P4D 3.29 sets the value to -1
(equals Ord(True) in Delphi).
In the P4D history I notices :
Version 3.28 (avr. 23, 2005)
Fixed a bug in PyObjectAsVariant thanks to Kiriakos Vlahos [kvlahos@...]Testing for Boolean values should be done before Integer values, as Boolean inherit from Integers.
Is this "new" behaviour related to the above change (causes script statements "if val==1:" has to be rewritten to "if val<>0:" which actually is
a better syntax for bool evaluations but unfortunely causes misbehaved scripts for our customers....) ?
Roar Larsen--------------------------------------------------------------------------------------TORDIVEL ASLade Alle 65 C, N-7041 Trondheim, NorwayTel : +47 7350 9220 Fax : + 47 2315 8701E-mail : roar@... Web : http://www.tordivel.no--------------------------------------------------------------------------------------...... THE VISION SOFTWARE HOUSE--------------------------------------------------------------------------------------
Joined: 29 Apr 2005
Posts: 103
Python bool represented in delphi
Hi Roar,
> I`ve just upgraded P4D from 3.27 to 3.29 (currently using Delphi 5)
>
> In my app I have a tag database accessible from python with
SetValue(tagname,value) and GetValue(tagname)
> (all values are represented by double`s inside the delphi app)
>
> With P4D 3.27 SetValue(tagname,True) sets the tagdatabase value to
1, while P4D 3.29 sets the value to -1
> (equals Ord(True) in Delphi).
>
> In the P4D history I notices :
>
> Version 3.28 (avr. 23, 2005)
>
> a.. Fixed a bug in PyObjectAsVariant thanks to Kiriakos
Vlahos [kvlahos@l...]
> Testing for Boolean values should be done before Integer
values, as Boolean inherit from Integers.
>
>
> Is this "new" behaviour related to the above change (causes script
statements "if val==1:" has to be rewritten to "if val<>0:" which
actually is
> a better syntax for bool evaluations but unfortunely causes
misbehaved scripts for our customers....) ?
Your SetValue function will invoke PyObjectAsVariant, which will
detect the boolean Python value and convert it into a proper boolean
variant, which will then be casted to an integer as -1.
So, you`re right!
To avoid this side effect, simply rewrite your SetValue function to
detect the type of value and if it`s True or False, then convert it
to your expected integer value (from Delphi, you can compare the
object to Py_True and Py_False).
You can also rename your SetValue function to _SetValue and define a
new Python function like this:
def SetValue(tagname, value):
if value is True:
value = 1
elif value is False:
value = 0
_SetValue(tagname, value)
VariantAsPyObject was not changed since 3.27.
Bye,
Morgan
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