Hi,
I'd like to understand how one can surgically add a piece to a long type
chain of something like string in julia.
Say I want to update the printing of expression objects.
So:
module M
import Base.string
function string(ex::Expr)
if ex.head == :$
string("\$(", map(string, ex.args)..., ")")
else
Base.string(ex)
end
end
end
However, if it executes the last command in the list, this somehow calls my
string function rather than the Base string function, leading to an
infinite recursion.
If I name the function differently and don't override Base.string, eg:
module M
function tostring(ex::Expr)
if ex.head == :$
string("\$(", map(tostring, ex.args)..., ")")
else
string(ex)
end
end
end
then the string(ex) call never calls tostring again (for obvious reasons).
Which means that if I want to implement my own custom string function on
expressions, I have to actually replicate the logic for EVERY type
possible, which is a LOT of work. I'd rather not do this, and I was hoping
to understand why I can't just exist as a new method definition that will
work only on a specific type (expr) in this case, and do what would
normally be right in other cases.
Vishesh
