ExprTools provides tooling for working with Julia expressions during metaprogramming. This package aims to provide light-weight performant tooling without requiring additional package dependencies.

Alternatively see the MacroTools package for more powerful set of tools.

Currently, this package provides the splitdef, signature and combinedef functions which are useful for inspecting and manipulating function definition expressions.

  • splitdef works on a function definition expression and returns a Dict of its parts.
  • combinedef takes Dict from splitdef and builds it into an expression.
  • signature works on a Method returning a similar Dict that holds the parts of the expressions that would form its signature.


julia> using ExprTools

julia> ex = :(
           function Base.f(x::T, y::T) where T
               x + y
:(function Base.f(x::T, y::T) where T
      #= none:3 =#
      x + y

julia> def = splitdef(ex)
Dict{Symbol,Any} with 5 entries:
  :args        => Any[:(x::T), :(y::T)]
  :body        => quote…
  :name        => :(Base.f)
  :head        => :function
  :whereparams => Any[:T]

julia> def[:name] = :g;

julia> def[:head] = :(=);

julia> def[:body] = :(x * y);

julia> g_expr = combinedef(def)
:((g(x::T, y::T) where T) = x * y)

julia> eval(g_expr)
g (generic function with 1 method)

julia> g_method = first(methods(g))
g(x::T, y::T) where T in Main

julia> signature(g_method)
Dict{Symbol,Any} with 3 entries:
  :name        => :g
  :args        => Expr[:(x::T), :(y::T)]
  :whereparams => Any[:T]