Cfrgtkky

When I write the template below, where:

• the first parameter has been designed for optional headers:


• the second has been designed to pass to tabularx.

I get the following error: Forbidden control sequence found while scanning use of @tempc. end{extabularx}

newenvironment{extabularx}[2]{%

    rowcolors{1}{gray!25}{white}%

    rownum=0%

    tabularx{linewidth}{#2}%

        toprule%

        %ifxempty#1relaxelse(rowcolor{gray!50} #1tabularnewline)fi%

        ifthenelse{empty#1}{%

            relax

        }{%

            rowcolor{gray!50}%

            #1tabularnewline%

            midrule%

        }%

}{%

        bottomrule%

    endtabularx%

}

Without IF statements it works fine, while with the if or ifx or ifthenelse statements it doesn't work.

As you have provided no test file or example of how the command is used it is hard to help in detail but

%ifxempty#1relaxelse(rowcolor{gray!50} #1tabularnewline)fi%

This is syntactically correct but tests if the first token in #1 is the token empty
if it is, that token is removed but remaining tokens of # are executed, followed by relax. If #1 does not start with empty then it typesets a ( followed by rowcolor which will always give an error as it has to be the first command in the row, but is following ( here.

That was probably not the test intended (you mention it doesn't work but leave us to guess what you wanted it to do)

ifthenelse{empty#1}{%

    relax

}{%

    rowcolor{gray!50}%

    #1tabularnewline%

    midrule%

}%

ifthenelse does not work via expansion so you do not want to use this here. the test clause with empty is wrong but even if that were fixed, you would not be able to use rowcolor or multicolumn etc that need to be at the start of the row.

Possibly you want to replace all of the code I highlighted by

    ifrelaxdetokenize{#1}relax

     expandafter@gobble

   else

     expandafter@firstofone

    fi

    {rowcolor{gray!50} #1tabularnewlinemidrule}%

assuming @ is a letter when you make the definitiuon (so in a package or after makeatletter in the preamble)

That would use an expandable test to check if #1 is empty, and use it to make a grey heading row if not empty.