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johnzabroski_wam's avatar
johnzabroski_wam
Copper Contributor
Oct 21, 2019
Solved

Is =IF true/false conditions non-strict or strictly evaluated?

I am researching this, and unfortunately, Microsoft Excel documentation doesn't clearly explain this simple concept.  In programming language theory, IF is lazy/non-strictly evaluated if it doesn't...
developer
excel
Formulas and Functions
Macros and VBA
  • JKPieterse's avatar
    JKPieterse
    Oct 24, 2019

    As far as I know, Excel does short-circuiting on IF and does not evaluate the "other part". You should be able to check that by logging which cells call your UDF (application.caller returns a pointer to that cell):

    Public Function foobar()
    Debug.Print Application.Caller.Address
End Function
JKPieterse's avatar
JKPieterse
Silver Contributor
Oct 24, 2019

As far as I know, Excel does short-circuiting on IF and does not evaluate the "other part". You should be able to check that by logging which cells call your UDF (application.caller returns a pointer to that cell):

Public Function foobar()
    Debug.Print Application.Caller.Address
End Function
johnzabroski_wam's avatar
johnzabroski_wam
Copper Contributor
Oct 29, 2019

JKPieterse Thanks for your helpful reply.

 

I was able to figure out that the issue was that my RtdServer was blocking the Excel UI thread, which caused unexpected behavior.  In addition, I discovered that in Excel 2007, Excel began supporting multi-threaded workbook calculations, and in Excel 2013, further enhanced multi-threaded workbook calculations with settings to disable on enable on a per-sheet basis these calculations.  I believe I had something like 84 cells calling my RtdServer via:

=IF(Some_Named_Cell, RTD("ProgId",,topic1,topic2,topic3,topic4)

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