UndefVarError accessing LasIO.epsg_code (with 'import LasIO')

[Joshua Olson]

It's buried in src/srs.jl, but it's used in a test like LasIO.epsg_code (and the readme points to the tests for usage).

[Joshua Olson]

I ended up copying epsg_code and the constants it uses into my code.

[Martijn Visser]

The epsg_code function is not exported, thus it is only available as LasIO.epsg_code if you do using LasIO. This will work just as well. If you prefer not having to prepend LasIO., you can also add using LasIO.epsg_code, this will make it available directly:

julia> using FileIO, LasIO

julia> header, points = load("srs.las")
(LasHeader with 10 points.
, Array{LasIO.LasPoint1,1} with 10 points.
)

julia> LasIO.epsg_code(header)
Nullable{Int64}(32617)

julia> using LasIO.epsg_code

julia> epsg_code(header)
Nullable{Int64}(32617)

See also the summary of module usage in the julia docs, where the example p is also not exported.

[Joshua Olson]

Note to others who come across this issue:

Julia doesn't have import aliases at this time, and unfortunately it's in style to pollute one's script's namespace with using...

[Martijn Visser]

If you don't want anything in your namespace, you could use

import LasIO

And if you want an alias for LasIO, you could follow that by

const L = LasIO

[Joshua Olson]

I really need to read the Modules docs better. One can use using without pollution, I guess?

[Martijn Visser]

One can use using without pollution, I guess?

Nope, you can use import for that.

[Joshua Olson]

Nope, you can use import for that.

It seems I wasn't clear; the following doesn't work for me:

import FileIO, LasIO
header, points = FileIO.load("srs.las")
LasIO.epsg_code(header) // error

[Martijn Visser]

Huh strange. Can you reproduce that in a clean Julia v0.6 session?

julia> import FileIO, LasIO

julia> header, points = FileIO.load("srs.las")
(LasHeader with 10 points.
, Array{LasIO.LasPoint1,1} with 10 points.
)

julia> LasIO.epsg_code(header)
Nullable{Int64}(32617)

[Joshua Olson]

$ julia
               _
   _       _ _(_)_     |  A fresh approach to technical computing
  (_)     | (_) (_)    |  Documentation: https://docs.julialang.org
   _ _   _| |_  __ _   |  Type "?help" for help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 0.6.2 (2017-12-13 18:08 UTC)
 _/ |\__'_|_|_|\__'_|  |  
|__/                   |  x86_64-pc-linux-gnu

julia> import FileIO, LasIO
      
julia> header, points = FileIO.load("2726-17-15.las") # the LAS file I have
(LasHeader with 449138 points.
, LasIO.LasPoint1[LasPoint(z=408460, classification=2)
, LasPoint(z=410290, classification=7)
, LasPoint(z=408510, classification=2)
, LasPoint(z=408500, classification=8)
, LasPoint(z=411340, classification=5)
, LasPoint(z=409540, classification=4)
, LasPoint(z=408420, classification=8)
, LasPoint(z=408480, classification=2)
, LasPoint(z=408480, classification=2)
, LasPoint(z=408570, classification=2)
  …  LasPoint(z=403920, classification=8)
, LasPoint(z=403640, classification=8)
, LasPoint(z=403880, classification=8)
, LasPoint(z=403660, classification=2)
, LasPoint(z=403780, classification=2)
, LasPoint(z=403640, classification=8)
, LasPoint(z=403850, classification=8)
, LasPoint(z=403560, classification=8)
, LasPoint(z=403760, classification=8)
, LasPoint(z=403970, classification=8)
])

julia> LasIO.epsg_code(header)
ERROR: UndefVarError: epsg_code not defined
Stacktrace:
 [1] macro expansion at ./REPL.jl:97 [inlined]
 [2] (::Base.REPL.##1#2{Base.REPL.REPLBackend})() at ./event.jl:73

[Martijn Visser]

Oh sorry, this has nothing to do with import/using, this is just a function that is not released yet:
v0.0.1...master

To get it right now, you can do Pkg.checkout("LasIO") to get the master branch. We should probably tag another release soon.

[Joshua Olson]

facepalm

Sorry to waste your time.