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jbranchaud
64 lines
1.5 KiB
Markdown
64 lines
1.5 KiB
Markdown
# Use Rescue As Part Of Inline Statement
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In Ruby I typically think of `rescue` as block syntax that I can use to handle
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exceptions.
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```ruby
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begin
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User.update!(password:)
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rescue
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puts "There was an issue updating the password"
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end
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```
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The `rescue` keyword can also be used as part of an inline statement as a way of
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providing a _fallback_ value when the first part of the statement raises.
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For instance, if I'm trying to access some value on an array that happens to be
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`nil`, it is going to raise:
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```ruby
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> scores.first
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(irb):7:in '<main>': undefined method 'first' for nil (NoMethodError)
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```
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I can instead tack on a `rescue 0` which will give it `0` as a fallback value:
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```ruby
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> scores.first rescue 0
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=> 0
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```
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Of course, there are more idiomatic ways to handle this kind of situation in
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Ruby. Maybe something like this:
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```ruby
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> Array(scores).first || 0
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=> 0
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```
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Another way I've seen this inline rescue used is to print out the exception
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caused by that line of code, using `$!` (the global variable for the most
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recently raised exception).
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```ruby
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> scores.first rescue puts $!
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undefined method 'first' for nil
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=> nil
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```
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That is a one-liner for the following:
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```ruby
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begin
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scores.first
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rescue => e
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puts e
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end
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```
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The big caveat that goes with this is the same one that goes with any other
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blanket `rescue` block. If you are indiscriminately rescuing exceptions without
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being intentional about what you are rescuing and why, you could be potentially
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burying exceptions that you need to know about.
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