# Why is there an inconsistent behaviour in PyCall while adding a directory to the path?

**URL:** <https://discourse.julialang.org/t/why-is-there-an-inconsistent-behaviour-in-pycall-while-adding-a-directory-to-the-path/26934>\
**Category:** New to Julia\
**Tags:** question\
**Created:** [July 29, 2019, 10:35am UTC](https://discourse.julialang.org/t/why-is-there-an-inconsistent-behaviour-in-pycall-while-adding-a-directory-to-the-path/26934 "2019-07-29T10:35:08Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![jishnub](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jishnub/32/33620_2.png) [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Post date:** [July 29, 2019, 10:35am UTC](https://discourse.julialang.org/t/why-is-there-an-inconsistent-behaviour-in-pycall-while-adding-a-directory-to-the-path/26934/1 "2019-07-29T10:35:08Z")

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I’m trying to add the current directory to `sys.path`. The step works if I set index using a string, but fails for the recommended dot overload, or if I use a symbol to access the path.

```julia
julia> using PyCall

julia> s=pyimport("sys")
PyObject <module 'sys' (built-in)>

julia> s.path
4-element Array{String,1}:
 "/project/jb6888/anaconda3/lib/python37.zip"           
 "/project/jb6888/anaconda3/lib/python3.7"              
 "/project/jb6888/anaconda3/lib/python3.7/lib-dynload"  
 "/project/jb6888/anaconda3/lib/python3.7/site-packages"

julia> pushfirst!(PyVector(s.path),pwd())
PyObject ['/home/jb6888', '/project/jb6888/anaconda3/lib/python37.zip', '/project/jb6888/anaconda3/lib/python3.7', '/project/jb6888/anaconda3/lib/python3.7/lib-dynload', '/project/jb6888/anaconda3/lib/python3.7/site-packages']

julia> s.path
4-element Array{String,1}:
 "/project/jb6888/anaconda3/lib/python37.zip"           
 "/project/jb6888/anaconda3/lib/python3.7"              
 "/project/jb6888/anaconda3/lib/python3.7/lib-dynload"  
 "/project/jb6888/anaconda3/lib/python3.7/site-packages"

```

The `sys.path` is unchanged this way. Using a symbol doesn’t work as well

```julia
julia> pushfirst!(PyVector(s[:path]),pwd())
┌ Warning: `getindex(o::PyObject, s::Symbol)` is deprecated in favor of dot overloading (`getproperty`) so elements should now be accessed as e.g. `o.s` instead of `o[:s]`.
│ caller = top-level scope at none:0
└ @ Core none:0
PyObject ['/home/jb6888', '/project/jb6888/anaconda3/lib/python37.zip', '/project/jb6888/anaconda3/lib/python3.7', '/project/jb6888/anaconda3/lib/python3.7/lib-dynload', '/project/jb6888/anaconda3/lib/python3.7/site-packages']

julia> s.path
4-element Array{String,1}:
 "/project/jb6888/anaconda3/lib/python37.zip"           
 "/project/jb6888/anaconda3/lib/python3.7"              
 "/project/jb6888/anaconda3/lib/python3.7/lib-dynload"  
 "/project/jb6888/anaconda3/lib/python3.7/site-packages"

```

but using a string works even though the method is deprecated

```julia
julia> pushfirst!(PyVector(s["path"]),pwd())
┌ Warning: `getindex(o::PyObject, s::AbstractString)` is deprecated in favor of dot overloading (`getproperty`) so elements should now be accessed as e.g. `o."s"` instead of `o["s"]`.
│ caller = top-level scope at none:0
└ @ Core none:0
PyObject ['/home/jb6888', '/project/jb6888/anaconda3/lib/python37.zip', '/project/jb6888/anaconda3/lib/python3.7', '/project/jb6888/anaconda3/lib/python3.7/lib-dynload', '/project/jb6888/anaconda3/lib/python3.7/site-packages']

julia> s.path
5-element Array{String,1}:
 "/home/jb6888"                                         
 "/project/jb6888/anaconda3/lib/python37.zip"           
 "/project/jb6888/anaconda3/lib/python3.7"              
 "/project/jb6888/anaconda3/lib/python3.7/lib-dynload"  
 "/project/jb6888/anaconda3/lib/python3.7/site-packages"

```

I’m using PyCall v1.91.2, which seems to be the recent version

---

<div class="post-metadata">

**Author:** ![jishnub](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jishnub/32/33620_2.png) [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Post date:** [July 29, 2019, 10:40am UTC](https://discourse.julialang.org/t/why-is-there-an-inconsistent-behaviour-in-pycall-while-adding-a-directory-to-the-path/26934/2 "2019-07-29T10:40:15Z")

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It seems I hadn’t read the docs (or even the deprecation message) carefully, and it should be

```julia
pushfirst!(PyVector(s."path"),pwd())

```

with `path` as a string. The behavior is different otherwise

```julia
julia> s.path
5-element Array{String,1}:
 "/home/jb6888"                                         
 "/project/jb6888/anaconda3/lib/python37.zip"           
 "/project/jb6888/anaconda3/lib/python3.7"              
 "/project/jb6888/anaconda3/lib/python3.7/lib-dynload"  
 "/project/jb6888/anaconda3/lib/python3.7/site-packages"

julia> s."path"
PyObject ['/home/jb6888', '/project/jb6888/anaconda3/lib/python37.zip', '/project/jb6888/anaconda3/lib/python3.7', '/project/jb6888/anaconda3/lib/python3.7/lib-dynload', '/project/jb6888/anaconda3/lib/python3.7/site-packages']

```

Using the string returns a `PyObject` which is then extended. Without a string it returns an array which is not linked to the `PyObject` anymore.