Hey all, I’m attempting to find the julia definition for the println method as I want to replace it with my own custom println method that performs a flush(stdout) after every println I’ve found this but it doesn’t seem to actually define the println function. Here is what I have so far: #Hack t…

I also tried the following, but it gives a stack overflow err: import Base.println original_println = Base.println println(s::String) = begin original_println(">$s") flush(stdout) end

Regarding println: since it has multiple methods, you cannot find the definition. Eg methods(println) should list them all. That said, overwriting a method in Base is almost surely not the way you want to do this. I asked a similar question a while ago, you may find the solution helpful: …

For most output stream types, println should already be line-buffered. What are you writing to?

Hi Stefan/Tamas, Thanks for taking the time to respond. The reason i’m trying to force the flush is that I’m executing a julia compiled .EXE (PackageCompiler) in an HPC environment, where the STDOUT is captured to a .txt file Without the println/flush hack I posted above, it will buffer all the s…

When implementing any IO method, you want to implement the method that takes an initial io::IO argument. So you’d want to implement: import Base.println function println(io::IO, s::String) println(io, s) flush(io) end Of course, doing this sort of “monkey patching” is fragile (at best) be…

Hey Matt - thanks for the input. I’m aware of the danger - as you said though I’m hoping that this is relatively side effect free. Unfortunately your sample causes a stack overflow exception - is there a way of calling the original method when overwriting the method?

Oh of course — yes, the way that I’d go about this is to shadow println with your own definition. That will allow you to still refer to the base method and only apply to your own namespaces: println(args...) = println(stdout, args...) println(io::IO, args...) = Base.println(io, args...) function p…

[image] mbauman: println(args…) = println(stdout, args…) println(io::IO, args…) = Base.println(io, args…) function println(io::IO, s::String) Base.println(io, s) flush(io) end Unfortunately this stack overflows for me too - however I did have to add in import Base.println before the code othe…

Yes, that’s what I was saying with: Note that you must define this before referring to println as once you’ve called Base’s implementation println you’re no longer able to shadow it with your own definition. You’ll need to restart your Julia session or create a new module to allow the shad…

Or simply call it something else (e.g. flushprintln)

Issues with println buffering output when redirecting stdout to a txt file

General Usage

jonbarkerlondon May 1, 2019, 4:15pm 9

Unfortunately this stack overflows for me too - however I did have to add in import Base.println before the code otherwise it wouldn’t compile. Is this preventing the shadow?

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Issues with println buffering output when redirecting stdout to a txt file

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