CODEWITHSUNDEEP
rubyperformanceidioms
Max Wallace
Max Wallace

Reputation: 3758

Ruby - cleanest way to return a value if truthy, or execute arbitrary code

I'm coding something in Ruby where, given a value foo output from a method call, I want to:

The simplest naive way to implement this is probably:

foo = procedure(input)

if foo
  foo
else
  log_error
  default
end

but this feels overly verbose because foo is repeated three times, and this style is very imperative.

What's the cleanest, most idiomatic way to write this?

(Performance matters-- let's assume that foo is truthy in the vast majority of cases.)

Upvotes: 5

Views: 364

Answers (5)

Cary Swoveland
Cary Swoveland

Reputation: 110725

All things considered, I would go with:

foo = procedure(input)
return foo if foo
log_error
default

Upvotes: 0

Max Wallace
Max Wallace

Reputation: 3758

For the sake of completeness (and since no one has posted it yet) I'll add my original attempt at an answer:

procedure(input) || proc {
  log_error
  default
}.call

I can't think of any reason to use this over @mwp's answer:

procedure(input) || begin
  log_error
  default
end

because of the extra overhead (performance and readability) involved in creating the Proc object. Though some quick benchmarking reveals that the performance difference should be negligible in most cases, since the Proc object doesn't seem to be created unless procedure(input) is falsy.

Upvotes: 0

mwp
mwp

Reputation: 8467

This is a rare case where Ruby's anonymous block is actually useful:

foo = procedure(input) || begin
  log_error
  default
end

Upvotes: 4

Arsen
Arsen

Reputation: 10951

You can write that if log_error returns a true value

foo || log_error && default

If not:

foo || (log_error; default)

Upvotes: 2

Jörg W Mittag
Jörg W Mittag

Reputation: 369526

Living off of Ruby's Perl heritage:

foo = procedure(input) and return foo
log_error
default

Upvotes: 4

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