Ruby procs can unexpectedly unpack arrays into multiple block parameters, while lambdas enforce arity and raise ArgumentError instead.

Font Awesome icons can be used directly from Sass without adding them to the DOM, using icon constants and mixins for :before or :after content.

CarrierWave url escapes non-ASCII characters while path returns the local filesystem path; use the right method for links, images, and send_file.

Cron schedules are easy to mistype, and invalid syntax only appears when crontab tries to install the file. CronMaker helps build valid expressions and check them quickly.

IRB and Rails console sessions can time code execution directly with measure; older versions can use Benchmark.measure for manual timing.

Rails 3+ script/runner debugging needs rdebug because --debugger is gone; Ruby-debug must be available and required to enter the debugger from a script.

Printing from .bashrc can break non-interactive commands like scp; checking for an interactive shell keeps startup output limited to terminal sessions.

Single-page previews for PDF and TXT uploads can be generated with CarrierWave and RMagick by rendering the first page as a JPG thumbnail.

Rails 3.2.16 and 4.0.2 can emit deprecation warnings for invalid I18n locales after upgrades; I18n.enforce_available_locales controls whether unsupported locales are validated.

SimpleDelegator on Ruby 1.8 can be prohibitively slow because it defines methods for every target method; DelegateClass(User) is often much faster for fixed model types.

File attachments can be assigned to model attributes and related objects in Cucumber scenarios, including polymorphic associations and timestamp setup.

Virtual integer attributes in Rails can lose form selections and type casting on validation roundtrips; an auto-coerced accessor keeps values as integers or nil.

Spreewald fails with ActiveRecord::AdapterNotSpecified when database.yml defines Cucumber settings instead of test settings. Renaming the environment entry to test resolves the adapter error.

RubyMine 5.4.3.2.1 can bind hotkeys for moving between split panes, useful for keyboard-driven pane switching.

Use ActiveRecord metadata to inspect a model field’s database type, such as integer, boolean, or datetime, without querying the value itself.

Feature definition for new teams and early products is often unclear when customer motivations and expected outcomes are hard to align. Job Stories apply jobs-to-be-done thinking instead of user stories.

Mobile-friendly, responsive jQuery date and time input picking without jQuery UI; the associated field cannot be typed into directly.

SSH agent forwarding lets remote servers use your local SSH keys without copying them, reducing key exposure while enabling convenient hop-through access.

Ruby security advisories and MRI release updates are published on ruby-lang.org, but no direct email subscription exists. An RSS-to-email service can deliver them by mail.

Rack middleware that blocks abusive clients and rate-limits requests with whitelists, blacklists, throttling, and request-based tracking.

Duplicate a MySQL database under a new name, including tables and data, by dumping the source and restoring it into a fresh schema.

Recursively select whitelisted keys and nested subkeys from a hash with deep_slice, preserving only the allowed structure.

Fast mobile taps suffer a 300ms click delay in browsers, making apps feel sluggish. FastClick removes the delay without changing existing click logic.

Generate full url_for links only within selected view or controller blocks, with temporary opt-out and optional fixed host. Asset URLs remain unchanged.