Disable items from an inherited class?

  • Thread starter Thread starter Steven Garrad
  • Start date Start date
S

Steven Garrad

Hi All
I have a custom class that is derived from the PictureBox class. One of the
properties from the PictureBox class is "SizeMode" and in my custom class I
want to disable the user from being able to modify this.

How can I remove this property from my class?

Thanks,
Steve
 
Hi,

Steven Garrad said:
Hi All
I have a custom class that is derived from the PictureBox class. One of
the properties from the PictureBox class is "SizeMode" and in my custom
class I want to disable the user from being able to modify this.

How can I remove this property from my class?
Click to expand...

you have to use the "new" keyword to hide the parent implementation:

new public XXXX SizeMode{


I do not remmber that SizeMode returns that's why the XXXX
 
"Ignacio Machin said:
Hi,



you have to use the "new" keyword to hide the parent implementation:

new public XXXX SizeMode{


I do not remmber that SizeMode returns that's why the XXXX
Click to expand...

... though there's nothing to stop a user casting your class to a
PictureBox, and using the original SizeMode property.

The only way to completely hide it is to encapsulate a PictureBox
internally, rather than deriving from it.
 
Steven Garrad said:
I have a custom class that is derived from the PictureBox class. One of the
properties from the PictureBox class is "SizeMode" and in my custom class I
want to disable the user from being able to modify this.

How can I remove this property from my class?
Click to expand...

Doing so would break Liskov's Substitutability Principle. Basically, if
you don't want type X to have all of the same members available as type
Y, you shouldn't derive type X from type Y in the first place.
 
It's not that I don't want it, but it's that I don't want it to be changed
by the user of the control.
 
Steven Garrad said:
It's not that I don't want it, but it's that I don't want it to be changed
by the user of the control.
Click to expand...

That's the same thing, effectively. You want to stop the user from
treating the control as if it were a normal PictureBox, which is what
Liskov's principle is about.
 
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