Difference between revisions of "Function Definition"

Revision as of 22:04, 11 July 2007

By default, the FM 7 API requires you to define each Function Definition in multiple files. This means duplication on Mac & Windows. It is possible to modify the main FMExample_Plugin.cpp file to include the definitions all in the one file, removing the duplication.

In this example, I have replaced the use of the 'FMExample.strings' file (Mac) and 'FMExamplePlugin.rc' file (Windows) to define each Function.

Step One

Define the Plugin Option String, Name and Description fields.

#define IDMA_Plugin_Name			"IDMA Plugin"
#define IDMA_Plugin_Description			"This plug-in provides additional functionality to FileMaker."

#define IDMA_Plugin_OptionString		"IDMA1nnYYnn"
//						 ^--^ || | |---- // No Win32s support
//						 |    || |------ // Want idle time 
//						 |    ||-------- // No old external functions
//						 |    |--------- // Has preferences dialog
//						 |-------------- // 'IDMA' plug-in ID

Note : I just copied these from the .strings or .rc file, then appended the #define name to the start instead.

Step Two

Define each of our plugins details.

For each Function Definition, I have created a set of definitions as below. The 'ID' as far as I can tell can be any number, but once you have set it for a function, you cannot change or else it will no longer link for any FileMaker database which calls that function. I have used increments of 10 so that I can insert a function at a later date if wanted.

// Function IDs				====WARNING :  ID Values are important.  Do not change once used, or will affect FileMaker linkage !!! ===
#define IDMA_Version_Name		"Version( \"Version\" )"
#define IDMA_Version_ID			201
#define IDMA_Version_Min		0
#define IDMA_Version_Max		1
#define IDMA_Version_Flags		fmx::ExprEnv::kMayEvaluateOnServer | fmx::ExprEnv::kDisplayInAllDialogs

#define IDMA_DoScript_Name		"idma_DoScript( Get(FileName) ; scriptname ; paramater )"
#define IDMA_DoScript_ID		211
#define IDMA_DoScript_Min		2
#define IDMA_DoScript_Max		3
#define IDMA_DoScript_Flags		fmx::ExprEnv::kMayEvaluateOnServer | fmx::ExprEnv::kDisplayInAllDialogs

Repeat the above for each additional Function Definition.

Step Three

We need to create a couple of new functions to replicate the 'Do_GetString' function that comes with the API to read our define's instead.

static fmx::TextAutoPtr _n(char * S)
{ // return the function name only as a FMX::TextAutoPtr.  eg. returns  'Version' from  'Version( \"Version\" )'

	fmx::TextAutoPtr	R;
	R->Assign(S);

	// The string for this whichStringID is a Function Prototype, but all the plug-in needs now is the Function Name by itself.
	fmx::TextAutoPtr		parenToken;		parenToken->Assign("(");

	unsigned long		originalSize = R->GetSize();
	unsigned long		firstParenLocation; 

	firstParenLocation = R->Find(*parenToken, 0);
	R->DeleteText(firstParenLocation, originalSize-firstParenLocation);

	return R;

} // Do_GetString (TextAutoPtr version)

static fmx::TextAutoPtr _p(char * S)
{ // return the function definition as a FMX::TextAutoPtr.  eg. returns  'Version( \"Version\" )'

	fmx::TextAutoPtr	R;
	R->Assign(S);

	return R;

} // Do_GetString (TextAutoPtr version)

Step Four

Modify the Do_Plugin_Inti() function as below

/* ::=- Do_PluginInit =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=:: */
static FMX_Long Do_PluginInit(FMX_Short version) 
{
	// Check the app API version
	if ((version < k70ExtnVersion) || (version > kMaxExtnVersion)) 
	{
		// This version of FileMaker is not supported; let FileMaker disable this 
		// plug-in and report the problem to the user.
		return (kBadExtnVersion);
	}

	// Initialise any variables as necessary.
	
	// Register plug-in functions
	fmx::QuadCharAutoPtr	pluginID('I', 'D', 'M', 'A');
	fmx::errcode			err;

	err = fmx::ExprEnv::RegisterExternalFunction(*pluginID, IDMA_Version_ID, *_n(IDMA_Version_Name), *_p(IDMA_Version_Name), IDMA_Version_Min, IDMA_Version_Max, IDMA_Version_Flags, Do_Version );
	err = fmx::ExprEnv::RegisterExternalFunction(*pluginID, IDMA_DoScript_ID, *_n(IDMA_DoScript_Name), *_p(IDMA_DoScript_Name), IDMA_DoScript_Min, IDMA_DoScript_Max, IDMA_DoScript_Flags, Do_StartScript	 );	
	
	// Return kCurrentExtnVersion to enable the plug-in in FileMaker.
	return (kCurrentExtnVersion);

} // Do_PluginInit

Notice that our actual Function Definition is now a single line per definition.