On Oct 19, 2016 7:26 PM, "Alex Mellnik" <a.r.mell...@gmail.com> wrote:
>
> Here's my bizarre find of the day. Most functions can be overwritten
without problems:
>
> function add7(i)
> 7 + i
> end
> Out[1]:
> add7 (generic function with 1 method)
> In [2]:
>
> add7(0)
> add7(0)
> Out[2]:
> 7
> In [3]:
>
> function add7(i)
> 9 + i
> end
> function add7(i)
> 9 + i
> end
> Out[3]:
> add7 (generic function with 1 method)
> WARNING: Method definition add7(Any) in module Main at In[1]:2
overwritten at In[3]:2.
> In [4]:
>
> add7(0)
> Out[4]:
> 9
>
> However, others can not:
>
> using DataFrames
> df = DataFrame(A=[1,2,3], B=["A", "B", "C"])
> println(df)
> 3×2 DataFrames.DataFrame
> │ Row │ A │ B │
> ├─────┼───┼─────┤
> │ 1 │ 1 │ "A" │
> │ 2 │ 2 │ "B" │
> │ 3 │ 3 │ "C" │
> In [3]:
>
> row[:A] > 2
> function filter(row)
> if row[:A] > 2
> return 1
> else
> return 3
> end
> end
> Out[3]:
> filter (generic function with 1 method)
> In [4]:
>
> [filter(row) for row in eachrow(df)]
> [filter(row) for row in eachrow(df)]
> Out[4]:
> 3-element Array{Int64,1}:
> 3
> 3
> 1
> In [5]:
>
> rand() > 0.5
> function filter(row)
> if row[:A] > 2
> return 2
> else
> return 4
> end
> end
> WARNING: Method definition filter(Any) in module Main at In[3]:2
overwritten at In[5]:2
> Out[5]:
> filter (generic function with 1 method)
> .
> In [6]:
>
> [filter(row) for row in eachrow(df)]
> Out[6]:
> 3-element Array{Int64,1}:
> 3
> 3
> 1
>
> What is it about this second example that prevents the newer method from
being used?
Nothing about it but how you use it. It's inlined to the comprehension.
