pgfplots: How to add a calculation in /.code=...?

I don't know why it failed neither. But after some try, I found the following code works. I think there may exist some expansion problem if we directly use the pgf's math calculation functionality. So I use xfp package for calculation.

documentclass[border=10pt, varwidth]{standalone}
usepackage{pgfplotstable}
pgfplotsset{compat=1.17}
usetikzlibrary{calc}
usepackage{pgfplots,xfp}

begin{document}
pgfplotstableread[col sep=comma,header=true]{
X,   Y,    Z
0,    0,   10
1,    0,   5
4,    1,   0
4,    2,   0
}{datatable}

begin{tikzpicture}
begin{axis}
addplot3[scatter, mark=*, only marks,
mark=cube*, mark size=5,
nodes near coords*=coordindex,
visualization depends on={z as zzz},
% % Works
scatter/@pre marker code/.append style={
/pgfplots/cube/size z=fpeval{12*zzz+0.2}
},
] table [x=X, y=Y] {datatable};
end{axis}
end{tikzpicture}
end{document}

I found the key handler /utils/exec=<code>, which is described in section 82.4.8 Handlers for Key Inspection of the TikZ-manual (not in the pgfplots-manual).

So

visualization depends on={thisrow{Z} as zzz}, 
scatter/@pre marker code/.append style={
/utils/exec=pgfmathsetmacromyheight{2.2*zzz+0.2},
/pgfplots/cube/size z=myheight        
}, % works as well

can be used.

documentclass[border=10pt, varwidth]{standalone}
usepackage{pgfplotstable}
pgfplotsset{compat=1.17}
usetikzlibrary{calc}
usepackage{pgfplots}

begin{document}
pgfplotstableread[col sep=comma,header=true]{
X,   Y,    Z
0,    0,   10
1,    0,   5
4,    1,   0
4,    2,   0
}{datatable}

begin{tikzpicture}
begin{axis}[]
addplot3[scatter, mark=*, only marks,
mark=cube*, mark size=5,  
nodes near coords*=coordindex,
visualization depends on={thisrow{Z} as zzz}, 
% Works
%scatter/@pre marker code/.append style={
%/pgfplots/cube/size z=15   
%}, % works
% Works as well
scatter/@pre marker code/.append style={
/utils/exec=pgfmathsetmacromyheight{2.2*zzz+0.2},
/pgfplots/cube/size z=myheight        
}, % works as well
] table [x=X, y=Y] {datatable};
end{axis}
end{tikzpicture}
end{document}