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Re^2: functions with optional arguments in Windows DLLs

by spurperl (Priest)
on Dec 13, 2007 at 20:08 UTC ( #656903=note: print w/replies, xml ) Need Help??

in reply to Re: functions with optional arguments in Windows DLLs
in thread functions with optional arguments in Windows DLLs

Indeed, you're right about optional arguments in C. So I guess the DLL I'm looking at (rmchart) wasn't written in C, but probably some kind of Basic). This is how the particular function I'm interested in is described:
nResult (LONG) = RMC_Draw2File( ByVal nCtrlId (LONG), ByRef sFileName (ASCIIZ), Optional ByVal nWidth (LONG), Optional ByVal nHeight (LONG), Optional ByVal nJPGQualityLevel (LONG) )
And judging by the description, the behavior I need happens when the optional args are not provided.

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Re^3: functions with optional arguments in Windows DLLs
by BrowserUk (Pope) on Dec 13, 2007 at 20:35 UTC

    According to this, optional arguments are 'filled in' to their default values, by the compilers of languages that support them. It also says that the default values should be clearly documented.

    The upshot appears to be that you will have to pass the default values when calling from a language that does not support this behaviour. So, you will need to look up the dfault values and provide them explicitly either every time you call via Win32::API or supply a wrapper function that fills them in.

    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
      Yes, I suppose I'll have to do that. Thanks for the help.

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