Creating implementation for idiom 205 : Get an environment variable

Idiom

# 205 Get an environment variable

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Read an environment variable with the name "FOO" and assign it to the string variable foo. If it does not exist or if the system does not support environment variables, assign a value of "none".

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Other implementations

with Ada.Environment_Variables;

Foo : constant String :=
      Ada.Environment_Variables.Value (Name    => "FOO",
                                       Default => "none");

#include <stdlib.h>

const char * foo = getenv("FOO");
if (foo == NULL) foo = "none";

(def foo
  (or (System/getenv "FOO") "none"))

#include <cstdlib>
#include <string>

const char* tmp = std::getenv("FOO");
std::string foo = tmp ? std::string(tmp) : "none";

string foo = Environment.GetEnvironmentVariable("FOO");
if (string.IsNullOrEmpty(foo)) foo = "none";

Demo

import std.process : environment;

string foo = environment.get("FOO", "none");

Demo
Doc

import 'dart:io';

var foo = Platform.environment["FOO"] ?? "none";

foo = System.get_env("FOO", "none")

Foo = os:getenv("FOO","none").

  call get_environment_variable ("FOO", length=n, status=st)
  if (st /= 0) then
    foo = "none"
  else
    allocate (character(len=n) :: foo)
    call get_environment_variable ("FOO", value=foo)
  end if

import "os"

foo := os.Getenv("FOO")
if foo == "" {
	foo = "none"
}

Demo
Doc

import "os"

foo, ok := os.LookupEnv("FOO")
if !ok {
	foo = "none"
}

Demo
Doc

def foo = System.getenv('FOO') ?: 'none'

Demo
Doc

import Control.Exception (IOException, catch)
import System.Environment (getEnv)

do
  foo <- catch (getEnv "FOO") (const $ pure "none" :: IOException -> IO String)
  -- do something with foo

const foo = process.env.FOO ?? 'none'

const foo = process.env["FOO"] || "none";

String foo = System.getenv("foo");
if (foo == null) {
	foo = "none";
}

val foo = System.getenv("FOO") ?: "none"

Demo
Doc

foo = os.getenv("FOO") or "none"

$foo = getenv("FOO") ?: "none";

Demo
Doc

uses sysutils;

var
  foo: string;
begin
  foo := GetEnvironmentVariable('FOO');
  if (foo = '') then foo := 'none';
end.

use 5.010;

my $foo = $ENV{FOO} // 'none';

from os import getenv

foo = getenv('FOO', 'none')

import os

foo = os.environ.get('FOO', 'none')

import os

try:
    foo = os.environ['FOO']
except KeyError:
    foo = "none"

foo = ENV["FOO"]

use std::env;

let foo = env::var("FOO").unwrap_or("none".to_string());

Demo
Doc

use std::env;

if let Ok(tnt_root) = env::var("TNT_ROOT") {
     //
}

use std::env;

let foo = match env::var("FOO") {
    Ok(val) => val,
    Err(_e) => "none".to_string(),
};

Demo
Doc

use std::env;

let foo = match env::var("FOO") {
    Ok(val) => val,
    Err(_e) => "none".to_string(),
};

| foo |
foo := CEnvironment getUserEnvironment at: 'FOO' ifAbsent: [ 'none' ].

foo = IIf(Environ("FOO") = "", "none", Environ("FOO"))

imports System

Dim _foo as String
Try
	foo = Environment.GetEnvironmentVariable("FOO")
Catch ex as Exception
	foo = "none"
End Try

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