Flexible way for text formatting - Another use of ANY type

Strucc.c — Tue, 10 Jun 2025 21:17:41 -0000

***... This is just one way to do, please let me know, if you have other idea ...*** It is quite a common demand - especially when developing low level function blocks, drivers - to easily and safely generate meaningful log messages. However, using the standard libraries, CONCAT, TO_STRING, the amount of code used for logging might easily exceed the actual code. It just looks silly, especially for people coming from the C, C++ or C# world... They want to do something like this: ~~~ PLCLog.DEBUG('Got param ID:%d; Type:%s Flags:%04X; Len:%d; ', dwID, strTypeClass, dwFlags, dwDataLen); ~~~ The goal here is the *small footprint, flexibility* and not really the *performance*. The problem is however, that the printf like calls available in CODESYS libraries are only handling one placeholder (I can't see a way to map \*\*args, or va_list to IEC code...), and start to behave crazy if there are more placeholders than arguments. So, here comes a workaround: ----- ~~~ // Just a tricky wrapper call, to allow sprintf like functionality with multiple placeholders and // arguments of ANY type. I Mostly use it for debug log generation - it was not intended // for fast performance or 100% compliance. Not a very nice implementation, and in my experiance // can cause access violation ... // // The purpose is to implement building string with a very small foorptint in the code. // For example: // // PLCLog.DEBUG( PE6( // 'Param ID:%d; Type:%s Flags:%04X; pData:%016X; Len:%d; DrvSpec:%016X', // dwID, strTypeClass, dwFlags, pData, dwDataLen, dwDriverSpec // )); // // As illustrated - due to the limitations of ANY inputs (can't be optional), // a set of helper functions is provided PE1..PE9 for the given numver of parameters. // // Limitations: // - It's based on CODESYS String Utilities... (STU)... I_Strings ? Ergh... // ... Could use IECStringutils.Printf - see in the code // - String length 255 // - Placeholders are from standard implementation (not same as in visualization) // - Due to ANY parameters, only parameters with Read/write access can be used... // means : no properties (??? Should be), function call results, or any // ad-hoc calculated values. // // Just take it easy, let me know if you have a better way for this feature FUNCTION _SPrintf_Segments : STRING(255); VAR_INPUT strFormat : STRING(255); END_VAR VAR_IN_OUT aArgs : ARRAY[*] OF __SYSTEM.AnyType; END_VAR VAR_OUTPUT lBound : DINT := LOWER_BOUND(aArgs, 1); uBound : DINT := UPPER_BOUND(aArgs, 1); END_VAR VAR iLenFormat : INT := 0; iSegmentCnt : INT := 0; iSegmentStart : INT := 1; strSegment : STRING(255); iPos : INT := 0; iRes : INT; END_VAR VAR_STAT CONSTANT byPc : BYTE := 37; // '%' END_VAR ~~~ ~~~ _SPrintf_Segments := UTF8#''; iPos := 0; iLenFormat := STU.LEN(strFormat); iSegmentStart := 1; iSegmentCnt := 0; lBound := LOWER_BOUND(aArgs, 1); uBound := UPPER_BOUND(aArgs, 1); FOR iPos := 0 TO iLenFormat DO IF strFormat[iPos] = byPC OR iPos >= iLenFormat THEN // Hit %, or end of format string IF strFormat[iPos+1] <> byPC THEN // skip %% IF iSegmentCnt > 0 THEN // The first segment extends to the 2nd % char.... strSegment := STU.MID(strFormat, iPos + 1 - iSegmentStart, iSegmentStart); iSegmentStart := iPos + 1; IF iSegmentCnt > UPPER_BOUND(aArgs, 1) THEN EXIT; END_IF iRes := STU.StuSprintf( pstFormat := ADR(strSegment), pVarAdr := aArgs[iSegmentCnt].pValue, udiVarType := aArgs[iSegmentCnt].TypeClass, pBuffer := ADR(_SPrintf_Segments) + TO_UDINT(LEN(_SPrintf_Segments)), dwBufferSize := SIZEOF(_SPrintf_Segments) - TO_UDINT(LEN(_SPrintf_Segments)) ); END_IF iSegmentCnt := iSegmentCnt + 1; ELSE iPos := iPos +1; END_IF END_IF END_FOR IF iPos < iLenFormat THEN // If more placeholders than arguments, just add the remaining of the format string.... _SPrintf_Segments := STU.CONCAT(_SPrintf_Segments, STU.MID(strFormat,iLenFormat,iPos+1)); END_IF ~~~ ----- Well, this is not too bad... so far, but it still requires an array as a parameter, what can bot be done in a compact way within the code (?). So here comes a helper function: ~~~ UNCTION PE4 : STRING(255); VAR_INPUT strFormat : STRING(255); // Format string Value1 : ANY; // Value for 1st placeholder Value2 : ANY; // Value for 2nd placeholder Value3 : ANY; // Value for 3rd placeholder Value4 : ANY; // Value for 4th placeholder END_VAR VAR aArgs : ARRAY[1..4] OF __SYSTEM.AnyType := [ Value1, Value2, Value3, Value4 ]; END_VAR ~~~ ~~~ PE4 := _Sprintf_Segments(strFormat, aArgs); ~~~ ----- Yes... Unfortunately, it is not possible to make input variables of ANY type optional... So unfortunately, there is a different helper function for 2, 3, 4 ... 9 parameters. :( Have a better idea? This way, the final call looks like: ~~~ PLCLog.DEBUG( PE4('Got param ID:%d; Type:%s Flags:%04X; Len:%d;', dwID, strTypeClass, dwFlags, dwDataLen) ); ~~~

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Flexible way for text formatting - Another use of ANY type