How to split table creation into commands

How to split table creation into separate commands or macros:

begin{tabularx}{textwidth}{X|X}
    A & B
end{tabularx}

Like this:

newcommand{tableHeader}{begin{tabularx}{textwidth}{X|X}}
newcommand{tableRow}{A & B}
newcommand{tableFooter}{end{tabularx}}

tableHeader
tableRow
tableFooter