rewrite implementation of existing method (fix) in another application

Paul Baumann
12 years ago

Post by Edmilson Bringel
It's possible to extend a class and override an existing class method (or
create an attribute) and save in My own Application?
Sorry to be late to the discussion.

You can easily change the behavior of existing methods with
PlbMethodOverrideSupport. Get the framework at
http://sourceforge.net/projects/methodoverride/. Load the
PlbMethodOverrideSupport application and then define #override_*
methods as extensions to the class from your own application code. The
override framework does a transient exchange of the methods and keeps
everything in sync whenever you recompile, load, unload, etc.. The old
method is available as #overridden_* and you can use that behavior.

You can extend attributes by using a reference collection. You'd define
methods on Object like #attributeAt: and #attributeAt:put: that refers
to a global weak key identity dictionary whose keys are objects with
extensions and whose values are attribute name/value pairs (a
dictionary). You'd also define getter and setter methods to access the
new variables using the new protocol. Simple.

Regards,

Paul Baumann

Hello, can I rewrite implementation of existing method of existing class from base libraries in my own application?

For example, I need to fix existing method asByteArray of class String (defined in base CLDT app) and I want to automaticaly load this fixed method with my configuration map. This is example only (in fact, we need to fix something in old Oracle classes in VAST 7).

It's something like extending existing classes with new methods in another app - but is possible to rewrite/fix some existing method?

Thanks, Petr Fischer

Hi Petr,

Obviously, the other replies have good advice especially about replacing the implementation of methods in the base product. However, sometimes, it is unavoidable.

Some years ago, Paul Baumann created a solution for this that works well. It is based on the very nature of Smalltalk, so it is clean. I recommend it for those cases where correcting base product code adn relaying the change to Instantiations for inclusion in future versions just isn't practical.


Found this on <a href="http://ibm.software.vasmalltalk.narkive.com/pqq3TEL8/extending-a-class-and-overriding-an-existing-method" target="_blank" rel="nofollow" onmousedown="this.href=&#39;http://www.google.com/url?q\x3dhttp%3A%2F%2Fibm.software.vasmalltalk.narkive.com%2Fpqq3TEL8%2Fextending-a-class-and-overriding-an-existing-method\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNGMxJEDYNxvIqrszsx-mgmZDFSkJw&#39;;return true;" onclick="this.href=&#39;http://www.google.com/url?q\x3dhttp%3A%2F%2Fibm.software.vasmalltalk.narkive.com%2Fpqq3TEL8%2Fextending-a-class-and-overriding-an-existing-method\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNGMxJEDYNxvIqrszsx-mgmZDFSkJw&#39;;return true;">http://ibm.software.vasmalltalk.narkive.com/pqq3TEL8/extending-a-class-and-overriding-an-existing-method. Paul's solution works well, with one caveat.  I recommend removing the installed overrides before saving an image and re-instating them after the save.

Paul Baumann
12 years ago

Post by Edmilson Bringel
It's possible to extend a class and override an existing class method (or
create an attribute) and save in My own Application?
Sorry to be late to the discussion.

You can easily change the behavior of existing methods with
PlbMethodOverrideSupport. Get the framework at
<a href="http://sourceforge.net/projects/methodoverride/" target="_blank" rel="nofollow" onmousedown="this.href=&#39;http://www.google.com/url?q\x3dhttp%3A%2F%2Fsourceforge.net%2Fprojects%2Fmethodoverride%2F\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNEmDGGmsIgus8ig6CsGCQl5TKrTZQ&#39;;return true;" onclick="this.href=&#39;http://www.google.com/url?q\x3dhttp%3A%2F%2Fsourceforge.net%2Fprojects%2Fmethodoverride%2F\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNEmDGGmsIgus8ig6CsGCQl5TKrTZQ&#39;;return true;">http://sourceforge.net/projects/methodoverride/. Load the
PlbMethodOverrideSupport application and then define #override_*
methods as extensions to the class from your own application code. The
override framework does a transient exchange of the methods and keeps
everything in sync whenever you recompile, load, unload, etc.. The old
method is available as #overridden_* and you can use that behavior.

You can extend attributes by using a reference collection. You'd define
methods on Object like #attributeAt: and #attributeAt:put: that refers
to a global weak key identity dictionary whose keys are objects with
extensions and whose values are attribute name/value pairs (a
dictionary). You'd also define getter and setter methods to access the
new variables using the new protocol. Simple.

Regards,

Paul Baumann

On Thursday, September 21, 2017 at 5:48:08 AM UTC-7, Petr Fischer wrote:

Hello, can I rewrite implementation of existing method of existing class from base libraries in my own application?

For example, I need to fix existing method asByteArray of class String (defined in base CLDT app) and I want to automaticaly load this fixed method with my configuration map. This is example only (in fact, we need to fix something in old Oracle classes in VAST 7).

It's something like extending existing classes with new methods in another app - but is possible to rewrite/fix some existing method?

Thanks, Petr Fischer