WidthLimitedIO

This Julia package exports a type, TextWidthLimiter <: IO, which can be used to limit output to no more than a specified number of characters. Demo:

julia> using WidthLimitedIO

julia> limitio = TextWidthLimiter(IOBuffer(), 15);     # generous limit

julia> println(limitio, "Hello, world!"); String(take!(limitio))
"Hello, world!\n"

julia> limitio = TextWidthLimiter(IOBuffer(), 5);      # restrictive limit

julia> println(limitio, "Hello, world!"); String(take!(limitio))
"Hell…"

julia> print(limitio, collect(1:15)); String(take!(limitio))
"[1, …"

A particular feature of the package is that it takes care to ensure that font-color changes and other features implemented via ANSI escape codes work properly:

julia> limitio = TextWidthLimiter(IOBuffer(), 5);

julia> printstyled(IOContext(limitio, :color=>true), "abcdef"; color=:red); String(take!(limitio))
"\e[31mabcd…\e[39m"

Thus the text-color was properly reset despite having exceeded the width of the buffer (as evidenced by the … character). When the string above is printed, it displays

abcd…

in red, while avoiding any corruption of any other on-screen display.

TextWidthLimiter was initially in Cthulhu.jl, but was redesigned and moved here to allow others to take advantage of it. It may be particularly useful for terminal programs where you may want to limit options to a single line.