mvellandi

mvellandi

Exploring Graphs with Elixir: Out of scope variable won't print (105, 107)

Exploring Graphs with Elixir by @tonyhammond: P.105, 107 — Ch 3 > Visualizing Graphs > Rendering with Graphviz

In making the water molecule and after writing a graph file using a variable, we’re told in 2 examples to print out the variable to inspect it using IO.puts

iex>​​ ​​with​​ ​​{:ok,​​ ​​dot}​​ ​​=​​ ​​Graph.to_dot(g)​​ ​​do​
​...>​​ ​​write_graph(dot,​​ ​​"dot/h2o.dot"​​)​
​...>​​ ​​end​
#GraphCommons.Graph<type: native, file: "...", data: "strict graph {\n...">​
​ 	
​iex>​​ ​​IO.puts​​ ​​dot​
strict graph {
​ 	    "O"
​ 	    "H"
​ 	    "H"
​ 	    "H" -- "O" [weight=1]
​ 	    "H" -- "O" [weight=1]
}​ 	
:ok

Maybe it’s just me, but this produces a function dot/0 not found error.
The variable “dot” is probably no longer in scope after having performed the first operation.

To make it print, I moved the print command above write_graph/2 command like so:

iex>​​ ​​with​​ ​​{:ok,​​ ​​dot}​​ ​​=​​ ​​Graph.to_dot(g)​​ ​​do​
...> IO.puts dot
...>​​ ​​write_graph(dot,​​ ​​"dot/h2o.dot"​​)​
...>​​ ​​end​
​ 
(graph output...)	​
#GraphCommons.Graph<type: native, file: "...", data: "strict graph {\n...">​

Marked As Solved

tonyhammond

tonyhammond

Author of Exploring Graphs with Elixir

Thanks for the catch.

I fixed this by reading it back in from the file store, as so:

iex> IO.puts read_graph(“dot/default.dot”).data

In two places.

Should be in the next beta.

Where Next?

Popular Pragmatic Bookshelf topics Top

telemachus
Python Testing With Pytest - Chapter 2, warnings for “unregistered custom marks” While running the smoke tests in Chapter 2, I get these...
New
jeffmcompsci
Title: Design and Build Great Web APIs - typo “https://company-atk.herokuapp.com/2258ie4t68jv” (page 19, third bullet in URL list) Typo:...
New
Alexandr
Hi everyone! There is an error on the page 71 in the book “Programming machine learning from coding to depp learning” P. Perrotta. You c...
New
mikecargal
Title: Hands-On Rust (Chap 8 (Adding a Heads Up Display) It looks like ​.with_simple_console_no_bg​(SCREEN_WIDTH*2, SCREEN_HEIGHT*2...
New
mikecargal
Title: Hands-on Rust: question about get_component (page 295) (feel free to respond. “You dug you’re own hole… good luck”) I have somet...
New
alanq
This isn’t directly about the book contents so maybe not the right forum…but in some of the code apps (e.g. turbo/06) it sends a TURBO_ST...
New
cro
I am working on the “Your Turn” for chapter one and building out the restart button talked about on page 27. It recommends looking into ...
New
jskubick
I’m running Android Studio “Arctic Fox” 2020.3.1 Patch 2, and I’m embarrassed to admit that I only made it to page 8 before running into ...
New
oaklandgit
Hi, I completed chapter 6 but am getting the following error when running: thread 'main' panicked at 'Failed to load texture: IoError(O...
New
Keton
When running the program in chapter 8, “Implementing Combat”, the printout Health before attack was never printed so I assumed something ...
New

Other popular topics Top

PragmaticBookshelf
Free and open source software is the default choice for the technologies that run our world, and it’s built and maintained by people like...
New
PragmaticBookshelf
Design and develop sophisticated 2D games that are as much fun to make as they are to play. From particle effects and pathfinding to soci...
New
AstonJ
Thanks to @foxtrottwist’s and @Tomas’s posts in this thread: Poll: Which code editor do you use? I bought Onivim! :nerd_face: https://on...
New
AstonJ
This looks like a stunning keycap set :orange_heart: A LEGENDARY KEYBOARD LIVES ON When you bought an Apple Macintosh computer in the e...
New
DevotionGeo
The V Programming Language Simple language for building maintainable programs V is already mentioned couple of times in the forum, but I...
New
PragmaticBookshelf
Rails 7 completely redefines what it means to produce fantastic user experiences and provides a way to achieve all the benefits of single...
New
Help
I am trying to crate a game for the Nintendo switch, I wanted to use Java as I am comfortable with that programming language. Can you use...
New
New
AstonJ
This is cool! DEEPSEEK-V3 ON M4 MAC: BLAZING FAST INFERENCE ON APPLE SILICON We just witnessed something incredible: the largest open-s...
New
PragmaticBookshelf
Use advanced functional programming principles, practical Domain-Driven Design techniques, and production-ready Elixir code to build scal...
New

Sub Categories: