Checking for Package Existence???

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I suggest a convention for user developed packages that are to provide functions to which other users can interface. I propose, the package should include a directive #define PACKAGE_PackageName (at the top). This will standardize and streamline how a user can test for existence ...

#ifdef PACKAGE_PackageName
   <code segment to compile when package exists>
#else
   <code segment to compile when package does not exist>
#endif


What do others think?
I initially proposed a convention that will not work because #define is local to the given procedure file.

So, here is my problem ...

Procedure File A -> IndependentModule=IMProcA
This procedure file contains a function called DoItA()

Procedure File B -> ModuleName=MNProcB
This procedure file contains a function called DoItB()

Function DoItB()
#if(exists("IMProcA#DoItA")==6)
    DoItA()
#else
    DoMyLocal()
#endif
    return 0
end


(1) When procedure file A is loaded and compiled BEFORE or AT THE SAME TIME that procedure file B is loaded and compiled, the function DoItB() calls DoItA().

(2) When procedure file B is loaded and compiled without procedure file A, DoItB() calls DoMyLocal().

(3) When procedure file B is loaded and compiled, AND THEN procedure file A is loaded and recompiled, DoItB() calls DoMyLocal().

How can I force DoItB() to recall DoItA() in (3)?

Basically, I want to write a procedure that will be aware whether a package is loaded or not, regardless of when the package was loaded - before, during, or after the procedure is compiled.

--
J. J. Weimer
Chemistry / Chemical & Materials Engineering, UAH

April 4, 2008 at 12:22 pm - Permalink
I would like to additionally suggest the ability to check for constant and strconstant definitions. Right now, neither:

#if exists("myConstant")

or

#ifdef myConstant

can do this. I'd like to know whether constants are set so I can bypass parts of my code that use them.

Rick

April 5, 2008 at 02:09 pm - Permalink
[quote=RGerkin]I would like to additionally suggest the ability to check for constant and strconstant definitions .... so I can bypass parts of my code that use them.
[/quote]

You may have already worked this out ... one suggestion is, when you are defining the constants, also define an associated symbol and test for its existence ...

#define kSetFitConstants
Constant kFitA = 1
Constant kFitB = 2
...
 
#ifdef kSetFitConstants
   <code when constants defined>
#else
   <code when constants not defined>
#endif


Alternatively, if you need this to work across multiple procedure files (for example, because one procedure file is a module of functions with constants that may or may not be #included for a main procedure file), using a dummy function should work ...

ProcFile A
Constant kFitA = 1
...
Function k_SetFitConstantsA()
    return 0
end
... (rest of procedure file) ...


ProcFile B
#if(exists("k_SetFitConstantsA")==6)
  <... code to run when module A with constants is #included ...>
#else
...
#endif


I agree otherwise with your suggestion. Testing #if(exists("ConstantName")==??) would be more direct. It would also be a reasonable way to have a standardized way to set/test for a package, rather than depending on testing for specific functions within a package ...

ProcFile ScreenSizer.ipf
Constant kPACKAGE_ScreenSizer=1
(... code for ScreenSizer package ...)


ProcFile XXX.ipf
#if(exists("kPACKAGE_ScreenSizer")==???)
  <... code if ScreenSizer package #included ...>
#else
  <... code if ScreenSizer package not #included ...>
#endif


--
J. J. Weimer
Chemistry / Chemical & Materials Engineering, UAH

April 8, 2008 at 05:51 am - Permalink