Bash and zsh has this ${VAR:-1} easy way to set a default value, when $VAR is
defined ${VAR:-1} will return the value of $VAR, and when $VAR is not defined,
${VAR:-1} will return the fallback default value -1, like:
$ echo ${VAR:-1}
-1
$ export VAR=15
$ echo ${VAR:-1}
15
This is very useful when define a function with default parameter, like:
hello() {
echo Hello ${1:-World}!
}
But fish doesn't support his trick, and there is no easy equivalent. I'm
thinking about defining a function to support this feature. This is my
implementation:
function fbd --description "Use second arg's vlaue as the fallback\
default value if the first arg is not defined"
echo $argv[1]
end
This function always output the first valid argument, so if the first argument
passed into fbd is not defined, the second argument will be first valid
argument:
$ fbd $VAR 1
1
$ set VAR 15
$ fbd $VAR 1
15
I just used fish for 1 week, I'm not sure if this fbd function has any issue,
or if there is a better way to implement in fish, please comment.
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