PostCommand() takes exactly 2 arguments (1 given)

[davidvadkerti]

Hi,

I was trying to run Purge Unused command by following code:

Command_ID=RevitCommandId.LookupPostableCommandId(PostableCommand.PurgeUnused)
UIApplication.PostCommand(Command_ID)

It gets me this error: 

PostCommand() takes exactly 2 arguments (1 given)

As I understand explanation at revitapidocs it should take just one argument. Can you tell me what I got wrong please?

Thanks a lot.

[jeremytammik · Accepted solution]

UIApplication is a class. You need an instance. I assume the instance is regarded as the first argument. Look at other PostCommand samples:

http://thebuildingcoder.typepad.com/blog/about-the-author.html#5.3

Cheers,

Jeremy

[davidvadkerti]

Thanks a lot Jeremy!

I am not familiar with C# in any sense, but your hint helped me a lot. I am using Python in Revit Python Shell and Pyrevit. My solution was like this:

#calling command Purge Unused
from Autodesk.Revit.UI import UIApplication, RevitCommandId, PostableCommand
doc = __revit__.ActiveUIDocument.Document

Command_ID=RevitCommandId.LookupPostableCommandId(PostableCommand.PurgeUnused)
#alternative way of getting command ID
#Command_ID=RevitCommandId.LookupCommandId("ID_PURGE_UNUSED")
uiapp = UIApplication(doc.Application)
UIApplication.PostCommand(uiapp,Command_ID)

I supose there isn't any other way to run command and submit it (like clicking on OK button). At least I haven't found any direct way in Revit API.

[jeremytammik]

You are still using a method on the class:

  UIApplication.PostCommand(uiapp,Command_ID)

The normal thing to do is to call a method on the class instance instead.

That is shorter and more readable:

  uiapp.PostCommand(Command_ID)

And, as you see, only one argument is provided.

The instance implicitly becomes an argument as well, the first argument, often called `this`.

Read a bit on Python object oriented programming basics before proceeding any further.

Cheers,

Jeremy

[davidvadkerti]

Thanks for advice.