A Julia debugger.
The debug interface is entered using the
using Debugger function foo(n) x = n+1 ((BigInt[1 1; 1 0])^x)[2,1] end @enter foo(20)
This interface allows for manipulating program execution, such as stepping in and out of functions, line stepping, showing local variables, and evaluating code in the context of functions.
st: show the status
n: step to the next line
u [i::Int]: step until line
ior the next line past the current line
s: step into the next call
so: step out of the current call
c: continue execution until a breakpoint is hit
bt: show a simple backtrace
stuffin the current function's context
fr [i::Int]: show all variables in the current or
f [i::Int]: go to the
i-th function in the call stack
up/down [i::Int]go up or down one or
ifunctions in the call stack
w add expr: add an expression to the watch list
w: show all watch expressions evaluated in the current function's context
w rm [i::Int]: remove all or the
i:th watch expression
o: open the current line in an editor
q: quit the debugger, returning
C: toggle compiled mode
L: toggle showing lowered code instead of source code
-: increase / decrease the number of lines of source code shown
nc: step to the next call
se: step one expression step
si: same as
sebut step into a call if a call is the next expression
sg: step into a generated function
An empty command will execute the previous command.
There are currently no designated commands in the debug mode for adding and removing breakpoints, instead they are manipulated using the API from the package JuliaInterpreter (which is reexported from Debugger). The different ways of manipulating breakpoints are documented here.
It is common to want to run a function until a breakpoint is hit. Therefore, the "shortcut macro"
@run is provided which is equivalent
of starting the debug mode with
@enter and then executing the continue command (
julia> using Debugger julia> breakpoint(abs); julia> @run sin(2.0) Hit breakpoint: In abs(x) at float.jl:522 >522 abs(x::Float64) = abs_float(x) About to run: (abs_float)(2.0) 1|debug> bt  abs(x) at float.jl:522 | x::Float64 = 2.0  sin(x) at special/trig.jl:30 | x::Float64 = 2.0 | T::DataType = Float64
Breakpoint on error
It is possible to halt execution when an error is thrown. This is done by calling the exported function
julia> using Debugger julia> break_on(:error) julia> f() = "αβ"; julia> @run f() Breaking for error: ERROR: StringIndexError("αβ", 2) In string_index_err(s, i) at strings/string.jl:12 >12 @noinline string_index_err(s::AbstractString, i::Integer) = About to run: (throw)(StringIndexError("αβ", 2)) 1|debug> bt  string_index_err(s, i) at strings/string.jl:12 | s::String = "αβ" | i::Int64 = 2  getindex_continued(s, i, u) at strings/string.jl:218 | s::String = "αβ" | i::Int64 = 2 | u::UInt32 = 0xb1000000 | val::Bool = false  getindex(s, i) at strings/string.jl:211 | s::String = "αβ" | i::Int64 = 2 | b::UInt8 = 0xb1 | u::UInt32 = 0xb1000000  f() at REPL:1 julia> JuliaInterpreter.break_off(:error) julia> @run f() ERROR: StringIndexError("αβ", 2) Stacktrace: [...]
In order to fully support breakpoints, the debugger interprets all code, even code that is stepped over.
Currently, there are cases where the interpreter is too slow for this to be feasible.
A workaround is to use "compiled mode" which is toggled by pressing
C in the debug REPL mode (note the change of prompt color).
When using compiled mode, code that is stepped over will be executed
by the normal julia compiler and run just as fast as normally.
The drawback is of course that breakpoints in code that is stepped over are missed.
The source code preview is syntax highlighted and this highlighting has some options.
The theme can be set by calling
theme is a Highlights.jl theme.
It can be completely turned off or alternatively, different quality settings for the colors might be chosen by calling
opt is a
The choices are
HIGHLIGHT_24_BIT. System colors works in pretty much all terminals, 256 in most terminals (with the exception of Windows)
and 24 bit in some terminals.