Add an example to read an environment variable #422
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Thanks for the contribution. The AppVeyor might be issues with the new Rust version on Windows. Let me dig into that for you to make sure master is working as the errors seem to be unrelated to the code change. |
src/basics.md
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| fn set_env_variable() { | ||
| env::set_var("CONFIG_FILE", "/tmp/config.toml"); |
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This is not a cross platform solution. I'm looking into the way the cookbook wants to recommend implementing file system abstractions. If you have any ideas, I'm interested. Right now I'm reading https://github.com/rust-lang-nursery/cli-wg/issues/10
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OK, I dug into it and there is a symptom of new regression due to rust version update, but that is not causing the error in AppVeyor. |
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@AndyGauge Thanks for the quick response. I will update the code to work on windows as well. |
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I've updated the code and removed all the file operations. I will squash the commits once everything is fine with this PR. |
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I forgot to mention putting in a few lines about the code, but you took care of that already! Thanks. |
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@AndyGauge I've squashed the commits. |
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Hi @Dineshs91 thanks for contributing! Could you look into some of the comments below?
| use std::env; | ||
| use std::path::PathBuf; | ||
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| # error_chain! { |
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this example can be completely rewritten without error_chain crate just change fn run() -> Result<()> to fn main() and remove Ok(()) and quick_main with all error chain specific code
| ## Read environment variable | ||
| [![std-badge]][std] [![cat-filesystem-badge]][cat-filesystem] | ||
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| Set an environment variable and read it back. If the variable is not found, then fallback |
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I'd suggest to link to std documentation for std::env::set_var and std::env::var
| # } | ||
| # } | ||
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| fn set_env_variable() { |
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I'm not really sold on using separate function to wrap one liner here.
Also the duplication of the "config.toml" string in two places might be slightly confusing how about we use different values?
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| # error_chain! { | ||
| # foreign_links { | ||
| # Utf8(std::str::Utf8Error); |
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Neither of these are needed for this example
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| let default_config_file = "config.toml"; | ||
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| let config_file_path = match env::var("CONFIG_FILE") { |
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This might a matter of taste but how about rewriting this simple transformation from match to Result combinators with something like:
let config_file_path = env::var("CONFIG_FILE")
.map(PathBuf::from)
.unwrap_or_else(|_| default_config_file.into());| } | ||
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| fn run() -> Result<()> { | ||
| set_env_variable(); |
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setting and reading the same env variable does not make a control flow that is close to being realistic. How about we set one variable and read another?
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@Dineshs91 would be happy to help you get the changes made to complete this. Please let me know if you are in need of support. |
fixes #401