Class: RuboCop::Cop::Kaizo::TempfileCreate

Inherits:
Base
  • Object
show all
Defined in:
lib/rubocop/cop/kaizo/tempfile_create.rb

Overview

Requires temporary files to be created with block-form Tempfile.create, and flags Tempfile.new, Tempfile.open, and blockless Tempfile.create.

Only the block form cleans up deterministically: the file is closed and removed when the block returns, however it returns. A Tempfile built with .new or .open is removed by a GC finalizer that runs at some unpredictable point -- possibly never -- and blockless Tempfile.create hands back a plain File that is never removed automatically at all.

There is no autocorrection: moving the file's users into the block is a restructuring, and the block's return value replaces the handle the old code held onto.

Configuration

No cop-specific options; the standard per-cop settings (+Enabled+, Severity, +Include+/+Exclude+) apply.

Examples:

# bad
file = Tempfile.new("report")
file = Tempfile.open("report")
file = Tempfile.create("report")

# good
Tempfile.create("report") do |file|
  file.write(data)
end

Constant Summary collapse

MSG = 
"Use `Tempfile.create` with a block instead of `Tempfile.%<method>s`; " \
"finalizer-based cleanup is unpredictable.".freeze
BLOCKLESS_CREATE_MSG = 
"Pass a block to `Tempfile.create`; " \
"without one the file is never removed.".freeze
RESTRICT_ON_SEND = 
%i[new open create].freeze

Instance Method Summary collapse

Instance Method Details

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/kaizo/tempfile_create.rb', line 46

def on_send(node)
  return unless tempfile_call?(node)
  return if node.method?(:create) && block_given_to?(node)

  range = node.receiver.source_range.join(node.loc.selector)
  add_offense(range, message: message_for(node))
end

#tempfile_call?(node) ⇒ Object 



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# File 'lib/rubocop/cop/kaizo/tempfile_create.rb', line 42

def_node_matcher :tempfile_call?, <<~PATTERN
  (send (const {nil? cbase} :Tempfile) _ ...)
PATTERN