Dockerfile if else condition with external arguments

I have dockerfile

FROM centos:7
ENV foo=42

then I build it

docker build -t my_docker .

and run it.

docker run -it -d  my_docker

Is it possible to pass arguments from command line and use it with if else in Dockerfile? I mean something like

FROM centos:7
if (my_arg==42)
     {ENV=TRUE}
else:
     {ENV=FALSE}

and build with this argument.

 docker build -t my_docker . --my_arg=42