Execute a Python Macro (Function) From Base and Return Value to Base

[SteveR]

Is it possible to have a python script return a value to LibreOffice Basic function when executed from Base?
I am using Ubuntu 14.04 with LibreOffice 4.4.3.2.

For Example- In Base I call the function below with: " If TableExists(strUSBTableName) Then …"

Function TableExists(strTableName As String) As Boolean
	rem http://www.access2base.com/access2base.html
	Dim odbDatabase As Object    
	Set odbDatabase = Application.CurrentDb()		  
    Dim i As Integer   
	docmd.runCommand("DBRefreshTables") 	       
        TableExists = False  
    	With odbDatabase	
    		For i = 0 To .TableDefs().Count - 1			
    			If strTableName = .TableDefs(i).Name Then               
                    TableExists = True
                    Exit For
                End If
    		Next i		
    	End With	
        Exit Function
    End Function

Can a Python script be used in the code above instead of Basic?
I suspect that it won’t really be a direct substitution.

Function TableExists(strTableName As String) As Boolean
    	    *** Some python script in here ***
            *** Return Some Value to Base (basic) ***
 End Function

[PYS]

Hi - Just a complement to the very good response from @doug (as usual). Your question is broader, but you can replace this particular procedure by:

Function TableExists(strTableName As String) As Boolean

TableExists = ThisDataBaseDocument.DataSource.Tables.hasByName(strTableName)

End function

Regards

[SteveR]

Thanks for contributing. My knowledge of uno Basic is minimal at best. In this particular case, it appears that I have to use Python to retrieve available disk space since uno Basic can’t do that. The response by @doug appears to do that.

[doug]

The way to do this is to call a macro using the UNO construct getScript(sScriptURI) and then call the invoke method for the object. That is the easy part. The hard part is figuring out the sScriptURI, which is a universal location for the script. There is a paucity of documentation about what, exactly, this is.

By trial and error you may find that a sScriptURI for a Basic macro looks like this:

"vnd.sun.star.script:Standard.Module1.SubName?language=Basic&location=application"

You can see the different elements. By further trial and error, you may find that a Python macro call_me.py with a method of the same name (call_me) saved in the following location:

/home/user/.config/libreoffice/{LOversionnumber}/user/Scripts/python/

Is accessible as follows:

"vnd.sun.star.script:call_me.py$call_me?language=Python&location=user"

Thus, if I have the following Python macro at the above location saved as call_me.py:

def call_me(*args ):
    return "call me"

Then if I invoke the following in Basic, it will return to the Basic macro the value set forth in the Python macro (“call me”):

Dim a(0),b(0),c(0) As Variant
scpr = ThisComponent.getScriptProvider
scmod = scpr.getScript("vnd.sun.star.script:call_me.py$call_me?language=Python&location=user")

returnFromPython = scmod.invoke(a,b,c)
MsgBox returnFromPython

location=share also is a valid location, I think, depending on where, exactly, the script is saved. For documentation of what are the arrays a, b, c, see the API reference. To make your Python macro work, you may need to redefine those.

(if this answers your question, please accept the answer by clicking the check mark () to the left)

[SteveR]

This appears to answer the question. The logic looks correct. My knowledge of uno Basic is minimal. It’s going to take me a while to parse through this. I hope that others will find your solution useful too. Thanks

[SteveR]

The “real” answer is the answer posted by Doug above. The purpose of this response is to show rudimentary code that functions based on the advice provided by Doug. While the code below works, modifications to the basic code structure have tended to fail. As the rudimentary minimally altered code works, these shortcomings can eventually be overcome through further research and trial and error. For now, this is usable code for conducting further experimentation.

Uno Basic function below:

Function dblTestPython(dblValue) As Double
		On Error Goto HandleError1001 
		dim a(0), b(0), c(0) as variant	
		a(0)= Forms("MainForm").Controls("Field1").value
		scpr = ThisComponent.getScriptProvider
		scmod = scpr.getScript("vnd.sun.star.script:call_me.py$call_me?language=Python&location=user")
		returnFromPython = scmod.invoke(a,b,c)
		print returnFromPython		
		Exit Function
	HandleError1001:
       	resume next
End Function   

Python script invoked by the Basic function above:

import os
def call_me(a):
	z = int(a) * 5 
	return z

[SteveR]

Since posting, I ran across this web-page: Transfer from Basic to Python.